The question arrived in the following form. “When it comes to fragrance application for men, what are the conventional application points under the 3-push and 4-push scenarios?” It was put to a general-purpose language model, which answered in a planning register, naming points and assigning sprays to them as though the matter had been settled by doctrine. It has not been settled. The conventional answers are widely repeated, mutually inconsistent in their details, and almost never accompanied by a statement of what the application is meant to achieve, against whom, at what distance, for how long, or at what cost to the people who did not ask to be included.

This article treats the question as a planning problem and adjudicates it. It generalises the question in three directions. The wearer may be a man or a woman. The application target may be a person, an animal, a bag, a garment or a room. The application platform may be a spray atomizer, a rollerball, a solid, an oil or a mist. The main line of the analysis concerns the case the question asked about, spray-applied fine fragrance on a human wearer, and the other targets and platforms are treated in shorter sections.

A hypothesis is stated before the analysis and adjudicated after it. The hypothesis is that the conventional three-spray and four-spray doctrines are sound. It is partially supported. The conventional doctrines place fragrance at broadly defensible points for reasons that are mostly wrong, and they prescribe a dose that is too large for the indoor encounters in which most fragrance is worn and too small for the outdoor ones. The four-push scenario is adequate for a full working day only when it is split into a morning application and a midday sequel, and in a small shared office no spray count is adequate at all, because the room rather than the wearer becomes the source. The difference between the conventional points for men and for women turns out to be a difference in clothing and hair, and it disappears when those are held fixed.

The article does six things the conventional literature does not. It converts sprays into dose, so that advice given for different products can be compared. It models how dose becomes concentration at a receiver, and shows that the detection radius grows only as the square root of the spray count. It adjudicates six scenarios against stated constraints on detection, collateral and overkill. It identifies the wearer as the least reliable judge of the application, for a physiological reason that has been measured. It states which of its results are structural, holding across every variation of its assumptions, and which are calibrated and should be read as illustrations. And it surveys the contemporary literature on fragrance as something applied and perceived, 2,541 works in sixteen clusters, and reports both what that literature has measured and the three questions at the centre of this article that it has not.

The article does not evaluate particular fragrances, does not rank brands, and does not offer a full analysis of offensive applications of aerosol delivery, which are adjacent and are bounded in a short section near the end.

The Question as Received, and Its Generalisation

Terms

The question’s unit is the push, one depression of an atomizer pump, which this article calls a spray or an actuation interchangeably. An application point is a location on the target where a spray is placed. Projection is the distance at which a fragrance can be detected by others, and sillage is the trade term for the trail a fragrance leaves in the air behind a moving wearer. Longevity is the time over which it remains detectable at all. The wearer is the person who applies the fragrance to themselves. A receiver is anyone who might detect it. An intended receiver is a receiver the application is meant to reach, and an unintended receiver is anyone else. The end state is the condition the application is meant to produce, stated in terms of who detects the fragrance, at what distance and for how long.

What the conventional answer leaves unstated

The conventional answer to the question as asked can be summarised quickly, and it is set out in detail in the section on placement. For men it places three sprays on the two sides of the neck and the chest, and a fourth on the back of the neck or the wrists. For women it places sprays on the wrists, the neck, behind the ears, the décolletage and the hair, with the inner elbows and the backs of the knees as further options.

What the conventional answer does not state is the end state. A three-push plan intended to be noticed by a dinner companion at half a metre and a three-push plan intended to be noticed by a colleague across an open-plan office are different plans that happen to share a spray count. The same spray count in a different product is a different dose. The same dose in a different room is a different exposure. An application point cannot be evaluated without an end state, and a spray count cannot be evaluated without a product, a room and a distance. This article supplies those, which is the whole of the difference between the question as received and the question as adjudicated.

The generalisation

The adjudicated question is the following. Given a wearer, a fragrance of known concentration delivered by a known platform, an application target, and a scenario specifying receivers, distances, air and duration, which spray count and which application points meet the end state without unacceptable collateral or overkill, and do the conventional answers coincide with them?

A Brief History of Where Fragrance Goes

The question of where to put fragrance is older than the spray, and the spray changed the question.

The earliest perfumer known by name is Tapputi, recorded on a cuneiform tablet from Assur of about 1200 BC. Egyptian practice used fragrant oils and unguents applied by hand, held in jars of the kind the Metropolitan Museum of Art preserves, and the incense kyphi, which was burned to scent spaces and not applied to people. Plutarch describes kyphi in On Isis and Osiris as a compound of sixteen ingredients, honey, wine, raisins and resins among them, mixed by perfumers while the sacred writings were read aloud to them, and Rimmel’s Book of Perfumes of 1865 repeats the account that at Heliopolis it was burned at sunset, after resin at sunrise and myrrh at midday. That is the earliest dosing schedule on record here, three applications a day at fixed times, and it was applied to a room. The conical headpieces shown in Egyptian tomb paintings were long read as cones of scented fat that melted onto the wearer. The two such cones recovered from Amarna and examined by Stevens and colleagues turned out to be hollow and made of wax, and the authors read them as symbolic rather than as a fragrance platform, so that interpretation is best treated as unresolved.

Hand application persisted for three thousand years, and with it a dosing regime set by the finger and the stopper rather than by the pump. Eau de Cologne, the dilute citrus water whose name became the generic term for a light fragrance, dates to the Farina business founded in Cologne in July 1709, and it was splashed and dabbed. Rimmel described it in 1865 as invented in the previous century by an apothecary of that city and extracted principally from the flowers, leaves and rind of the bitter orange and other citrus, which is the composition its name still implies. Eugène Rimmel, the London perfumer, advertised himself in 1862 as the patentee of a perfume vaporiser for balls, soirées and theatres, a device for scenting rooms, not people, and he also sold perfumed valentines, an early instance of fragrance applied to paper. The personal atomizer came from medicine. Allen DeVilbiss, a physician in Toledo, Ohio, built atomizers for the nose and throat, and was granted a United States patent for an atomizer, number 648,656, filed in 1899 and issued in 1900, and his son Thomas turned the company toward perfume atomizers, which became its best-selling product according to the University of Toledo’s account. Secondary accounts date the move into perfume to about 1907.

The spray made the dose discrete. A splash or a dab has no natural unit, while a pump delivers a fixed volume each time it is pressed, which is the only reason the question can be asked in pushes at all. Modern fine-fragrance pumps are manufactured to nominal doses, and Aptar’s VP4 pump, a widely used fragrance pump, is offered at 70, 100 and 140 microlitres per actuation. The planning value of 0.10 mL used here is the middle of that range. It also fixes the number of actuations a bottle holds. Writing $V_b$ for the bottle volume and $N_{\mathrm{day}}$ for the daily spray count, the bottle holds $N_b$ actuations and lasts $T_b$ days.

\[N_b = \frac{V_b}{v_s}, \qquad T_b = \frac{V_b}{v_s \, N_{\mathrm{day}}}\]

A 100 mL bottle holds between $100 / 0.14 = 714$ and $100 / 0.07 = 1{,}429$ actuations depending on the pump, and 1,000 at the planning value. At three sprays a day it lasts 333 days, and at four it lasts 250, so the choice between the two scenarios is also a choice about when the next bottle is bought.

The Hypothesis

A hypothesis that cannot fail is not worth adjudicating, so this one is stated with its rejection criteria attached.

Hypothesis. The conventional three-spray and four-spray doctrines are sound for spray-applied fine fragrance on a human wearer. The claim decomposes into three parts, each of which can be supported or rejected independently.

  • H1, dose. Three or four sprays is the smallest dose that meets a conversational-distance end state without unacceptable collateral or overkill, and the fourth spray adds less than the third.
  • H2, placement. The conventional application points are chosen for the mechanism that actually operates, which the conventional literature names as warmth at the pulse points.
  • H3, the wearer. The difference between the conventional application points for men and for women is a property of clothing and hair rather than of the wearer’s sex.

Rejection criteria. H1 is rejected in a scenario if the smallest adequate dose there is not three or four sprays, or if no dose is adequate. H2 is rejected if the named mechanism is not the operative one, and partially supported if the named mechanism operates but does not dominate. H3 is rejected if the wearer’s sex changes the preferred points once clothing, hair and the identity of the intended receiver are held fixed. The overall hypothesis is supported only if all three parts are supported, rejected if all three are rejected, and partially supported otherwise.

The criteria were written before the adjudication was run, and the scenario parameters were not revised after the results were seen, with one exception that is recorded in the Epistemic State section.

Planning Assumptions, Constraints and Restraints

Every quantity the adjudication uses is listed here with its class. Measured quantities come from a cited source. Calibrated quantities were chosen so that the model reproduces a commonly reported qualitative outcome, and they carry the weakest warrant in the article. Assumed quantities are planning values that a reader with better data should replace.

Symbol Quantity Planning value Class
$v_s$ Volume delivered per actuation 0.10 mL Measured range, value assumed
$\rho$ Density of the finished fragrance 0.82 g/mL Assumed from the ethanol density
$c$ Mass fraction of aromatic compounds 0.03 to 0.25 by class Measured range
$\eta$ Fraction of the spray that lands on the target 0.70 Assumed
$\tau$ Lumped emission time constant 3 h Assumed
$u$ Air speed past the wearer 0.1 m/s indoors, 1.0 m/s outdoors Assumed
$a$ Plume spread per metre of distance 0.3 Assumed
$C_{50}$ Median detection concentration of the blend, in total aromatic mass 30 µg/m³ Calibrated
$\sigma$ Spread of receiver thresholds, natural log units 1.2 Assumed
$C_{\mathrm{over}}$ Median concentration judged too strong $30\,C_{50}$ Assumed
$V$, $\lambda$ Room volume and air change rate By scenario Measured range

The calibrated threshold deserves a sentence of defence. Individual fragrance materials are detected at very low concentrations, linalool at 3.2 ng/L, which is 3.2 µg/m³, according to Elsharif, Banerjee and Buettner. A blend is diluted in its own carrier of weaker materials. Perfume engineering expresses each component’s contribution as an odour value, its vapour concentration $C_k$ divided by its detection threshold $\mathrm{ODT}_k$, and a component is perceptible when its odour value exceeds one. If the most potent component makes up a mass fraction $x_k$ of the aromatic material, the total aromatic concentration at which it reaches threshold follows directly.

\[\mathrm{OV}_k = \frac{C_k}{\mathrm{ODT}_k} = \frac{x_k \, C}{\mathrm{ODT}_k}, \qquad C_{50} \approx \frac{\mathrm{ODT}_k}{x_k}\]

With linalool at 3.2 µg/m³ making up a tenth of the aromatic mass, the blend reaches threshold at $3.2 / 0.1 = 32$ µg/m³ of total aromatic material. The approximation ignores the vapour-phase enrichment of volatile components and the interaction of components below their individual thresholds, so it supports the order of magnitude and nothing finer. The value of 30 µg/m³ was then chosen so that three sprays of eau de parfum are detectable at a little under two metres indoors when fresh, which matches the projection the trade literature commonly describes. It is the weakest number in the article, and the sensitivity analysis varies it by a factor of three in each direction.

The scenario distances follow the proxemic zones that Edward Hall set out in The Hidden Dimension, in which intimate distance extends to about 0.46 m, personal distance to 1.2 m and social distance to 3.7 m.

Constraints are conditions the plan must satisfy. The adjudication imposes three. An intended receiver must detect the fragrance more often than not, an unintended receiver must detect it no more than one time in five, and an intended receiver must find it too strong no more than one time in ten. Restraints are actions the plan may not take regardless of effect. The plan may not apply fragrance to a person who has not consented, may not exceed the limits set out in the safety section, and may not treat the wearer’s own nose as a measuring instrument, for reasons established in a later section.

The Dose Model

Mass per actuation

The quantity that matters is not the number of sprays but the mass of aromatic material placed on the target. Write $N$ for the number of actuations, $v_s$ for the volume each delivers in millilitres, $\rho$ for the density of the finished product in grams per millilitre, $c$ for the mass fraction of aromatic compounds, and $\eta$ for the fraction of the sprayed mass that lands on the target rather than in the air around it. The deposited aromatic mass $m_0$ in grams is then the product.

\[m_0 = N \, v_s \, \rho \, c \, \eta\]

The planning density of 0.82 g/mL sits above the density of ethanol, 0.789 g/mL at 20 °C, on the assumption that the dissolved aromatic material is denser than the solvent. For an eau de parfum at fifteen percent, one actuation of 0.10 mL at 0.82 g/mL carries $0.10 \times 0.82 \times 0.15 = 0.0123$ g, or 12.3 mg of aromatic material before deposition losses. Three actuations deposit $3 \times 12.3 \times 0.70 = 25.8$ mg on the wearer, and four deposit 34.4 mg. Not all of the deposited mass reaches the air. Some is absorbed through the skin, and Bronaugh and colleagues found that on unoccluded skin absorption varied widely between fragrance compounds, presumably because evaporation competes with penetration, while under occlusion more than half of the applied dose of the compound tested in humans was absorbed. Clothing over an application point is a partial occlusion, which is one reason the adjudication treats covered skin as a slower and lossier point. The figure that a reader should carry forward is that the entire three-spray scenario concerns about a quarter of a gram of product and about twenty-six milligrams of the material that is actually smelled.

The spray-equivalent

The original question was posed in sprays, and a spray is not a unit of dose. Four sprays of an eau de toilette at ten percent and four sprays of an extrait at twenty-five percent differ in aromatic mass by a factor of two and a half. Define the spray-equivalent $N_{\mathrm{eq}}$ as the dose expressed in actuations of a reference eau de parfum at $c_{\mathrm{ref}} = 0.15$, holding the pump volume and density fixed.

\[N_{\mathrm{eq}} = N \, \frac{c}{c_{\mathrm{ref}}}\]

Four sprays of eau de toilette are $4 \times 0.10 / 0.15 = 2.7$ spray-equivalents. Three sprays of an extrait at twenty-five percent are 5.0. Ten sprays of a body mist at two percent are 1.3. The three-push and four-push scenarios are therefore not comparable across products until they are converted, and much of the disagreement in published application advice is advice about different doses expressed in the same unit. Every result below is stated for the reference eau de parfum unless another class is named.

Class Aromatic fraction, planning value Mass per actuation Spray-equivalents per actuation
Body mist 0.02 1.6 mg 0.13
Eau de cologne 0.03 2.5 mg 0.20
Eau de toilette 0.10 8.2 mg 0.67
Eau de parfum 0.15 12.3 mg 1.00
Extrait or parfum 0.25 20.5 mg 1.67

Emission and Decay

The lumped emission model

A fragrance is a mixture of compounds with volatilities spanning several orders of magnitude, which is the physical basis of the top, heart and base structure described in the trade literature. Perfume engineering models each component separately, computing headspace concentrations from activity coefficients and dividing by each component’s detection threshold to obtain an odour value, an approach developed by the Rodrigues group at Porto from Mata, Gomes and Rodrigues onward and summarised by Rodrigues, Nogueira and Faria. The adjudication collapses that mixture into a single pool that empties at a rate proportional to what remains. Write $\tau$ for the emission time constant in hours and $t$ for the time since application. The emission rate $q$ in micrograms per second is then as follows.

\[q(t) = \frac{m_0}{\tau} \, e^{-t/\tau}\]

With $m_0 = 25.8$ mg and $\tau = 3$ h, the initial emission rate is $25{,}830 \text{ µg} / 10{,}800 \text{ s} = 2.39$ µg/s. Eight hours later it has fallen by a factor of $e^{8/3} = 14$.

This is the first simplification that a reader should distrust. A real fragrance front-loads its most volatile material, so the early emission is higher than the lumped model says and the late emission comes from a smaller and heavier residue. The adjudication results that depend on this simplification are flagged where they appear. Part of the deposited mass may not be emitted within a day at all. Malhiac et al 2026 found base-note material still retained on blotters after eight hours, and Hurley et al 2021 modelled 20 to 40 percent of the hydroxyl reactivity in commercial fragrance mixtures as evaporating too slowly to affect local air quality. A residue of that kind lowers the effective $m_0$ and moves every adjudicated count slightly upward.

Temperature

Evaporation from skin is governed by the vapour pressure of each compound, which rises steeply with temperature. The Clausius and Clapeyron relation, which descends from Clapeyron’s 1834 analysis of the motive power of heat, cited here in its 1843 German translation, and was given its thermodynamic form by Clausius in 1850, gives the ratio of vapour pressures, and therefore approximately of emission rates, at two absolute temperatures $T_1$ and $T_2$ for a compound with molar enthalpy of vaporisation $\Delta H_{\mathrm{vap}}$, where $R$ is the molar gas constant.

\[\frac{q(T_2)}{q(T_1)} \approx \frac{p(T_2)}{p(T_1)} = \exp\!\left[ \frac{\Delta H_{\mathrm{vap}}}{R} \left( \frac{1}{T_1} - \frac{1}{T_2} \right) \right]\]

For linalool, a common heart-note material, the Chemistry WebBook of the National Institute of Standards and Technology gives a measured enthalpy of vaporisation of 50.3 kJ/mol near its boiling point and standard values of 55.3 and 65.0 kJ/mol from two extrapolations. Skin is not uniformly warm. In normal-weight adults at rest in a thermoneutral room, Savastano and colleagues measured abdominal skin at 32.8 °C and the fingernail bed at 28.6 °C, and the extremities are generally cooler than the trunk, as Webb’s sixteen-site measurements also show. Taking $\Delta H_{\mathrm{vap}} = 55.3$ kJ/mol, $T_1 = 301.75$ K for the coolest distal skin and $T_2 = 305.95$ K for the trunk, the ratio is as follows.

\[\frac{q(305.95)}{q(301.75)} = \exp\!\left[ \frac{55{,}300}{8.314} \left( \frac{1}{301.75} - \frac{1}{305.95} \right) \right] = 1.35\]

Across the three enthalpies the factor runs from 1.32 to 1.43, and for a more typical two-kelvin difference between wrist and trunk it is about 1.15. Warmer skin emits faster and is exhausted sooner. It does not emit more in total, because the mass is fixed at application, so the time constant scales inversely with the emission factor.

\[\frac{\tau(T_2)}{\tau(T_1)} = \frac{q(T_1)}{q(T_2)}\]

The three-hour planning constant on the trunk becomes about $3 \times 1.35 = 4.1$ h on the coolest distal skin. Since the detection radius at application scales as the square root of the emission rate, the entire temperature advantage of trunk over extremity is worth $\sqrt{1.35} = 1.16$ in starting radius, which is almost exactly what a fourth spray adds to three. The temperature effect is real, it is the only part of the pulse-point rationale with a physical mechanism, and it is the size of one spray in four.

Transport to the Receiver

The near field

Between the wearer and a receiver at conversational distance, the fragrance travels as a plume carried and diluted by moving air. Indoors much of that air movement is generated by the wearer. A standing person heats the surrounding air and drives a rising boundary layer, which Craven and Settles measured as a plume reaching a time-averaged vertical velocity of about 0.24 m/s some 0.4 m above the head. Fragrance placed anywhere on the torso is collected by that flow and carried upward past the face, which matters for placement and is taken up in that section. A review by Zong et al 2022 reports the plume carrying floor-level particles into the breathing zone at concentrations up to four times the ambient, so even the lowest application points feed it. A Gaussian plume from a continuous point source has a centreline concentration inversely proportional to the air speed and to the product of its two lateral spreads. Taking both spreads to grow linearly with distance, $\sigma = a\,r$, the concentration $C$ at distance $r$ in metres is as follows.

\[C(r, t) = \frac{q(t)}{\pi \, u \, a^2 \, r^2}\]

At $t = 0$, three sprays, $u = 0.1$ m/s and $a = 0.3$, the concentration at one metre is $2.39 / (\pi \times 0.1 \times 0.09 \times 1) = 85$ µg/m³. At half a metre it is four times that, 338 µg/m³, and at the wearer’s own nose, about 0.2 m from the neck, it is 2,100 µg/m³.

The detection radius

Setting $C(r) = C_{50}$ and solving for $r$ gives the distance $r^{*}$ at which the median receiver can just detect the fragrance.

\[r^{*}(t) = \sqrt{ \frac{q(t)}{\pi \, u \, a^2 \, C_{50}} } = \sqrt{ \frac{N \, v_s \, \rho \, c \, \eta}{\pi \, u \, a^2 \, C_{50} \, \tau} } \; e^{-t/2\tau}\]

This is the central result on dose, and it does not depend on the calibrated threshold in the way the absolute numbers do. The detection radius grows with the square root of the spray count, and the area $\mathcal{A}$ within which the median receiver detects the fragrance grows linearly with it.

\[\frac{r^{*}_{N_2}}{r^{*}_{N_1}} = \sqrt{\frac{N_2}{N_1}}, \qquad \mathcal{A} = \pi \, r^{*2} \propto N\]

Going from three sprays to four multiplies the radius by $\sqrt{4/3} = 1.155$ and the detected area by $4/3$. Doubling the dose buys forty-one percent more radius. The absolute radius at application is 1.68 m for three sprays indoors and 1.94 m for four, but those numbers inherit the calibration of $C_{50}$ and are illustrative and not predictive.

The same expression yields a half-life for the radius. Because the radius decays as $e^{-t/2\tau}$, it halves after $2\tau \ln 2$.

\[t_{1/2}^{(r)} = 2\,\tau \ln 2 = 4.16 \text{ h} \quad \text{for } \tau = 3 \text{ h}\]

The radius half-life is independent of dose. No spray count changes how quickly the projected footprint shrinks. Dose sets the starting radius and nothing else.

The detection life at a fixed distance

The complementary question is how long a receiver at a fixed distance $r$ continues to detect. Setting $C(r, t) = C_{50}$ and solving for $t$ gives the detection life $t_{\mathrm{det}}$, which exists only if the fragrance is detectable at that distance at all.

\[t_{\mathrm{det}}(r) = \tau \ln \frac{q_0}{\pi \, u \, a^2 \, r^2 \, C_{50}}, \qquad q_0 = \frac{m_0}{\tau}\]

For three sprays at one metre indoors, $t_{\mathrm{det}} = 3 \ln (84.6 / 30) = 3.11$ h, and for four sprays it is 3.97 h. Because $q_0$ is proportional to $N$, the life added by one more spray depends only on the count already applied.

\[\Delta t_{\mathrm{det}} = \tau \ln \frac{N + 1}{N}\]

The second spray adds $3 \ln 2 = 2.08$ h, about 125 minutes. The fourth adds $3 \ln (4/3) = 0.86$ h, about 52 minutes. Each spray buys less time than the one before it, and the fourth buys under an hour.

Wind

Outdoors the air speed past the wearer rises by about an order of magnitude. Because the concentration is inversely proportional to $u$, the detection radius scales as $u^{-1/2}$. A breeze of 1.0 m/s shrinks the three-spray radius from 1.68 m to 0.53 m. Holding the radius fixed while the air speed changes from $u_1$ to $u_2$ requires the spray count to change in proportion.

\[\frac{N_2}{N_1} = \frac{u_2}{u_1} \quad \text{at fixed } r^{*}\]

Recovering the indoor three-spray radius in a 1.0 m/s breeze therefore requires $3 \times 1.0 / 0.1 = 30$ sprays. No conventional spray count projects outdoors in moving air the way it does indoors, and this is the one regime where the four-push scenario is underpowered rather than overpowered.

The far field, where the room becomes the source

In an enclosed space the plume does not leave. Ventilation rates span an order of magnitude. The United States Environmental Protection Agency’s Exposure Factors Handbook recommends a median of 0.45 air changes per hour for residences and reports a mean of 1.5 for non-residential buildings. Treat the room as a well-mixed volume $V$ in cubic metres ventilated at an air change rate $\lambda$ per hour. The room concentration $C_{\mathrm{room}}$ obeys a mass balance in which the wearer’s emission enters and the ventilation removes a fixed fraction per hour.

\[\frac{dC_{\mathrm{room}}}{dt} = \frac{q(t)}{V} - \lambda \, C_{\mathrm{room}}, \qquad C_{\mathrm{room}}(0) = 0\]

With the exponentially decaying source, the solution is as follows.

\[C_{\mathrm{room}}(t) = \frac{m_0}{\tau V} \cdot \frac{e^{-t/\tau} - e^{-\lambda t}}{\lambda - 1/\tau}\]

It peaks when its derivative vanishes.

\[t_{\mathrm{peak}} = \frac{\ln(\lambda \tau)}{\lambda - 1/\tau}\]

For a shared office of 30 m³ at one air change per hour, three sprays peak at $t = \ln 3 / (2/3) = 1.65$ h with a room concentration of 166 µg/m³. At that moment the plume adds only 49 µg/m³ at one metre. The room concentration exceeds the near-field concentration at conversational distance from twenty minutes after application onward, and it is the same everywhere in the room. In that regime the wearer is no longer the source in any operational sense. The room is the source, and every occupant is a receiver whether intended or not. This is the condition the trade literature describes as a fragrance that fills a room, and it is area denial in the literal sense of the term.

The open-plan office of 500 m³ at two air changes per hour holds the same three sprays at a peak of 6.0 µg/m³ after 1.08 h, a fifth of the median threshold, so the near field governs and the wearer remains the source. The difference between the two offices is a factor of thirty-three in $\lambda V$, and it decides the scenario before spray count is considered.

The room-regime number

The decision between the two regimes can be made before anyone sprays anything. Once $t \gg 1/\lambda$, the room solution approaches a fixed multiple of the current emission rate.

\[C_{\mathrm{room}}(t) \;\to\; \frac{q(t)}{V \left( \lambda - 1/\tau \right)}\]

Dividing by the near-field concentration at the intended receiver’s distance $r_i$ cancels the emission rate entirely and leaves a dimensionless room-regime number $\Pi$, with $\lambda$ and $1/\tau$ expressed per second.

\[\Pi = \frac{C_{\mathrm{room}}}{C(r_i)} = \frac{\pi \, u \, a^2 \, r_i^2}{V \left( \lambda - 1/\tau \right)}\]

When $\Pi$ exceeds one, the room is the source, and no spray count changes that, because $\Pi$ does not contain the dose. For the shared office, $\Pi = (\pi \times 0.1 \times 0.09 \times 1) / (30 \times 1.85 \times 10^{-4}) = 5.09$, and the model’s ratio of room to plume concentration at one metre is 4.74 at four hours and 5.06 at eight, converging on it. For the open-plan office $\Pi = 0.12$, and for dinner at half a metre in the restaurant $\Pi = 0.048$. The number is the formal version of the first thing to check, and it is computed from the room and the conversation distance alone. The near-field and far-field pair is not an invention of this article. It is the standard two-zone model of occupational hygiene, whose predictions Abattan et al 2021 compared with measurements across 21 studies, and it is recommended for cosmetic spray exposure by Steiling et al 2025.

A closed car is the limiting case. For times short compared with $1/\lambda$, ventilation has not yet acted and the room concentration is the emitted mass divided by the volume.

\[C_{\mathrm{room}}(t) \approx \frac{q_0 \, t}{V} \quad \text{for } t \ll 1/\lambda, \; t \ll \tau\]

Five minutes after three fresh sprays in a 3 m³ cabin, $C_{\mathrm{room}} \approx 2.39 \times 300 / 3 = 239$ µg/m³, eight times the median threshold, everywhere in the car.

Perception

Intensity grows slowly with concentration

Perceived odour intensity $\psi$ follows Stevens’ power law in concentration, introduced in Stevens’ 1957 paper, with an exponent $n$ well below one. The table of exponents reproduced by Moskowitz and colleagues gives 0.55 for coffee odour and 0.6 for heptane, and they note values as low as 0.2 to 0.3 for some odorants in a liquid diluent. The constant $k$ sets the scale and drops out of every ratio used here.

\[\psi = k \, C^{\,n}\]

At a fixed distance the concentration is proportional to the spray count, so two counts compare through the exponent alone.

\[\frac{\psi_{N_2}}{\psi_{N_1}} = \left( \frac{N_2}{N_1} \right)^{n}\]

With $n = 0.5$ the fourth spray raises perceived intensity at a fixed distance by $(4/3)^{0.5} - 1 = 15$ percent. With $n = 0.3$ it raises it by 9 percent. The fourth spray is mostly invisible to a receiver who was already detecting the third, and mostly visible to receivers who were not, because detection is a threshold event and intensity is not.

Receivers differ

Receivers do not share a threshold. Detection ability falls with age, and in the large sample of Doty and colleagues more than half of those aged 65 to 80 showed major impairment of smell identification. It differs slightly by sex, in a direction and size taken up in the section on the wearer. And it fails entirely for some compounds in some people. Sato-Akuhara and colleagues cite specific anosmia to the musk exaltolide in 7.2 to 9 percent of people of European descent and to muscone in 6 percent, a phenomenon first reported for musk by Whissell-Buechy and Amoore as odour-blindness with simple recessive inheritance, and Keller and colleagues tied variation in one odorant receptor gene to differences in how androstenone is perceived. A musk-heavy fragrance therefore has receivers for whom no dose is detectable, and the wearer may be one of them. The adjudication represents this by a log-normal distribution of thresholds, so the probability that a receiver drawn at random detects concentration $C$ is the standard normal distribution function $\Phi$ of the log ratio.

\[P_{\mathrm{det}}(C) = \Phi\!\left( \frac{\ln C - \ln C_{50}}{\sigma} \right)\]

The same form with the median overload concentration $C_{\mathrm{over}}$ in place of $C_{50}$ gives the probability $P_{\mathrm{over}}$ that a receiver finds the fragrance too strong.

\[P_{\mathrm{over}}(C) = \Phi\!\left( \frac{\ln C - \ln C_{\mathrm{over}}}{\sigma} \right)\]

With $\sigma = 1.2$, one standard deviation of threshold is a factor of $e^{1.2} = 3.3$ in concentration, so a receiver at the sixteenth percentile of sensitivity needs 3.3 times the concentration the median receiver needs.

Overkill is a near-field phenomenon. At half a metre, fifteen minutes after application, one spray produces about 104 µg/m³ and a four percent chance that the receiver finds it too strong. Three sprays produce 311 µg/m³ and a nineteen percent chance. At 0.3 m, which is the distance of an embrace, three sprays produce a forty-nine percent chance. The conventional three-push is therefore adjudicated, at intimate distance and in the first hour, as about as likely to be judged excessive as not.

The Wearer Is the Least Reliable Sensor

Every receiver in the adjudication is somebody other than the wearer, and that is deliberate. The wearer is the one receiver whose readings cannot be used.

Adaptation

Continuous exposure to an odour reduces its perceived intensity within minutes, and the effect is strongest for the person closest to the source. Dalton’s review of olfactory adaptation describes a stimulus-specific loss of sensitivity during exposure, with raised thresholds and reduced intensity above threshold, both depending on the concentration and the duration of exposure, and notes that the effect can be very long-lasting. The review does not supply time constants, but later experiments bracket them. Pierce and Simons 2018 found the perceived intensity of a continuously delivered odour significantly reduced at five minutes and at ten, and Hintschich et al 2024 found detection thresholds already significantly raised after ten minutes of continuous exposure. The values used below remain planning values, chosen within that bracket. Beekman et al 2022 measured the wearer directly, and found that wearing perfume in an amount judged about right significantly worsened the wearer’s odour threshold and discrimination, so the degradation is not confined to the fragrance worn. The wearer is the receiver with the highest exposure by an order of magnitude. Because the near-field concentration falls as the inverse square of distance, the ratio of the wearer’s exposure at $r_w$ to a receiver’s at $r_i$ is independent of everything else.

\[\frac{C(r_w)}{C(r_i)} = \left( \frac{r_i}{r_w} \right)^{2}\]

At 0.2 m from a neck application the near-field equation gives 2,100 µg/m³ at application, $(1/0.2)^2 = 25$ times, or twenty-five times what a receiver at one metre experiences. Model the wearer’s perceived intensity relative to its initial value as an adaptation factor $A(t)$ that decays from one toward a floor $\beta$ with a time constant $\tau_a$.

\[A(t) = \beta + (1 - \beta)\, e^{-t/\tau_a}\]

With an assumed floor of $\beta = 0.3$ and an assumed $\tau_a = 5$ min, the wearer perceives half the initial intensity at the adaptation half-time $t_{1/2}^{(a)}$.

\[t_{1/2}^{(a)} = \tau_a \ln \frac{1 - \beta}{0.5 - \beta}\]

That is $t = 5 \ln 3.5 = 6.3$ min. At that moment the emission rate is still $e^{-6.3/180} = 0.966$ of its initial value.

Six minutes after application the wearer believes half the fragrance has gone, and ninety-seven percent of the emission is still present.

The reapplication spiral

A wearer who uses perceived intensity as the measure of effectiveness and reapplies when it falls to half will reapply at about six minutes, adapt to the new level, and reapply again. Each cycle adds dose that every other receiver perceives at full sensitivity, because no other receiver has spent the morning at 0.2 m from the source. If the wearer reapplies the original dose every adaptation half-time $\Delta_r$, the emission rate at time $t$ is the sum over every application so far, with $k = \lfloor t / \Delta_r \rfloor$ reapplications.

\[q_{\mathrm{spiral}}(t) = \frac{m_0}{\tau} \sum_{j=0}^{k} e^{-(t - j \Delta_r)/\tau}\]

With $\Delta_r = 6.3$ min, nine reapplications fall within the first hour, and at $t = 1$ h the emission rate is 11.8 times what the single application alone would produce. The process has no internal stopping condition. It ends at the bottle, at the schedule, or at a remark from a colleague, and the remark is the only one of the three that carries information about the end state.

This is the mechanism behind the overapplication that the trade literature warns against, and the adjudication’s restraint follows from it. The wearer may not use self-perception to decide whether to reapply. Reapplication is scheduled in advance as a sequel, as in the open-plan case, or triggered by an independent observer. The independent observer serves as the plan’s red cell, a receiver who did not participate in the application and whose report is therefore not contaminated by it. A red cell can be a household member asked at the door, and it is the cheapest instrument in the plan.

A secondary effect compounds the first. The wearer adapts not only during the day but across days to a fragrance worn daily. Dalton and Wysocki exposed subjects continuously to one of two odorants in their own homes for two weeks and observed odorant-specific rises in detection threshold and falls in perceived intensity, with reduced sensitivity still evident in most subjects up to two weeks after the exposure ended. A signature fragrance is therefore perceived more weakly by its wearer each month while it is perceived identically by everyone else. The sensible response is to hold the dose fixed by count and to ignore the impression that the fragrance has grown weaker, because the impression measures the wearer and not the fragrance.

Scenarios and Adjudication

The scenarios

Six scenarios were defined before the adjudication was run. Each states an end state, the distance to the intended receiver, the distance to the nearest unintended receiver, and the air in which the encounter takes place.

Scenario Window after application Intended receiver Unintended receiver Air
S1 shared office 0.5 to 8.5 h 1.0 m 2.5 m 30 m³, 1 change per hour
S2 open-plan office 0.5 to 8.5 h 1.0 m 2.5 m 500 m³, 2 changes per hour
S3 interview 0.5 to 1.5 h 1.5 m None 30 m³, 1 change per hour
S4 dinner 0.25 to 4.25 h 0.5 m 2.0 m 200 m³, 3 changes per hour
S5 outdoor event 0.25 to 4.25 h 0.5 m 3.0 m Open air, 1.0 m/s
S6 elevator 0.5 to 0.55 h None 0.6 m Still air, 0.1 m/s

The elevator is not an end state anyone seeks. It is a phase line that every morning application crosses on the way to S1 or S2, and it is adjudicated as a constraint on those scenarios.

Measures of effectiveness

For each course of action the adjudication computes three measures, each averaged over the scenario’s time window. Detection $D$ is the mean probability that the intended receiver detects the fragrance. Collateral $K$ is the mean probability that the unintended receiver does. Overkill $O$ is the mean probability that the intended receiver finds it too strong. The concentration at each receiver is the near-field plume plus the room term.

\[D = \frac{1}{t_1 - t_0} \int_{t_0}^{t_1} P_{\mathrm{det}}\!\big( C(r_i, t) + C_{\mathrm{room}}(t) \big) \, dt\]

$K$ and $O$ follow by replacing the intended receiver’s distance $r_i$ with the unintended receiver’s distance $r_u$, or the detection probability with the overload probability.

\[K = \frac{1}{t_1 - t_0} \int_{t_0}^{t_1} P_{\mathrm{det}}\!\big( C(r_u, t) + C_{\mathrm{room}}(t) \big) \, dt, \qquad O = \frac{1}{t_1 - t_0} \int_{t_0}^{t_1} P_{\mathrm{over}}\!\big( C(r_i, t) + C_{\mathrm{room}}(t) \big) \, dt\]

A course of action is feasible when $D \geq 0.5$, $K \leq 0.2$ and $O \leq 0.1$. The recommended course of action $N^{\star}$ in each scenario is the smallest feasible spray count, because any spray beyond it buys detection the end state does not require at a cost in collateral and product.

\[N^{\star} = \min \left\{ N \in \{0, 1, \ldots, 6\} \;:\; D(N) \geq 0.5,\; K(N) \leq 0.2,\; O(N) \leq 0.1 \right\}\]

The collateral measure is a probability per unintended receiver, and a room usually holds more than one. With $n_u$ unintended receivers at comparable distance, the expected number who detect the fragrance over the window is their sum.

\[\mathbb{E}[n_K] = \sum_{j=1}^{n_u} K_j \approx n_u \, K\]

Eight colleagues within 2.5 m in the open-plan office, at the collateral of 0.15 that the split four-push produces below, give $8 \times 0.15 = 1.2$ colleagues detecting the wearer on an average day. The constraint of 0.2 per receiver is therefore not a promise that nobody notices. It is a promise that about one person in five does.

A bound on what distance alone can separate

In the near field, intended and unintended receivers differ only in distance, and the inverse-square law fixes how far apart their concentrations can be. On the log-normal threshold scale that gap is a fixed number of standard deviations, independent of dose.

\[\Delta z = \frac{\ln C(r_i) - \ln C(r_u)}{\sigma} = \frac{2 \ln (r_u / r_i)}{\sigma}\]

Holding the unintended receiver at the collateral limit $K_{\max}$ then caps the detection the intended receiver can reach at any instant, whatever the spray count, where $\Phi^{-1}$ is the inverse of the standard normal distribution function.

\[D_{\max} = \Phi\!\left( \Phi^{-1}(K_{\max}) + \Delta z \right)\]

For the offices, with $r_i = 1.0$ m and $r_u = 2.5$ m, $\Delta z = 2 \ln 2.5 / 1.2 = 1.53$ and $D_{\max} = \Phi(-0.84 + 1.53) = 0.75$. For dinner, with $r_i = 0.5$ m and $r_u = 2.0$ m, $\Delta z = 2.31$ and $D_{\max} = 0.93$. No spray count can make a fragrance more selective than the geometry of the encounter allows. The bound holds for the near field alone, and a room term only lowers it, which is why the shared office falls so far short of it.

Results for the reference eau de parfum

Each cell gives $D$, $K$ and $O$ in that order.

Scenario N = 1 N = 2 N = 3 N = 4 N = 5 N = 6
S1 shared office 0.53 / 0.48 / 0.01 0.72 / 0.68 / 0.03 0.81 / 0.78 / 0.05 0.86 / 0.84 / 0.08 0.90 / 0.87 / 0.11 0.92 / 0.90 / 0.13
S2 open-plan office 0.16 / 0.02 / 0.00 0.30 / 0.06 / 0.00 0.40 / 0.11 / 0.00 0.48 / 0.15 / 0.01 0.54 / 0.19 / 0.01 ✓ 0.59 / 0.23 / 0.01
S3 interview 0.70 / . / 0.01 ✓ 0.87 / . / 0.04 ✓ 0.93 / . / 0.08 ✓ 0.95 / . / 0.13 0.97 / . / 0.17 0.98 / . / 0.21
S4 dinner 0.69 / 0.09 / 0.01 ✓ 0.85 / 0.22 / 0.05 0.91 / 0.33 / 0.09 0.94 / 0.42 / 0.13 0.96 / 0.49 / 0.18 0.97 / 0.54 / 0.22
S5 outdoor 0.09 / 0.00 / 0.00 0.21 / 0.00 / 0.00 0.31 / 0.00 / 0.00 0.39 / 0.00 / 0.00 0.46 / 0.00 / 0.00 0.52 / 0.00 / 0.00 ✓
S6 elevator . / 0.74 / . . / 0.89 / . . / 0.94 / . . / 0.96 / . . / 0.98 / . . / 0.98 / .

A check mark denotes a feasible course of action, and a full stop denotes a measure that does not apply because the scenario has no such receiver.

S1, the shared office, has no feasible course of action at any spray count. Detection and collateral rise together and never separate by more than five points, because from twenty minutes onward the room term dominates both receivers equally. The office mate at 2.5 m smells what the visitor at 1.0 m smells. This result survived every sensitivity case in the next subsection, since it is a property of the room term and not of the threshold. The conventional three-push in this scenario delivers 0.81 detection to the intended receiver and 0.78 to the unintended one.

S2, the open-plan office, is feasible at five sprays and at no smaller single dose. The large ventilated volume keeps the room term low, so collateral stays bounded, but the eight-hour window asks a decaying source to perform at hour eight as it did at hour one. The conventional four-push misses the detection constraint by two points.

S3, the interview, is feasible from one spray to three. The smallest feasible dose is one. The scenario’s difficulty is not dose but the sign of the objective, which is taken up separately below.

S4, dinner, is feasible at one spray and at nothing larger. At half a metre the near field is strong, so a single spray is detected more often than not across four hours, and the second spray already pushes the diner at the next table past the collateral constraint. The conventional three-push violates the collateral constraint by thirteen points.

S5, the outdoor event, is feasible only at six sprays. Moving air dilutes by a factor of ten, and nothing below six reaches the detection constraint at half a metre. This is the only scenario in which more than four sprays is the adjudicated answer, and it is also the least robust result in the table.

S6, the elevator, is violated by every morning application. Thirty minutes after a single spray, a passenger at 0.6 m detects the wearer with probability 0.74. No spray count from one to six reduces that below the collateral constraint, so the elevator is not a decision point at all. It is a standing cost of any nonzero course of action, and the plan must either accept it or apply after the commute.

Concentration classes

Repeating the adjudication for the other two common classes moves the smallest feasible dose in the expected direction and changes no qualitative result.

Scenario Eau de toilette Eau de parfum Extrait
S1 shared office None None None
S2 open-plan office None up to six 5 3
S3 interview 1 1 1
S4 dinner 1 1 1
S5 outdoor event None up to six 6 4
S6 elevator Standing cost Standing cost Standing cost

The conventional three-push appears as the smallest feasible dose exactly once, for an extrait in the open-plan office. The four-push appears exactly once, for an extrait outdoors.

The sequel, in which the four-push is split

The open-plan result is driven by exponential decay over an eight-hour window, and the obvious response is to treat the day as two phases. A sequel is an application planned in advance for a later phase, here at 4.5 h, which is about the middle of the working day. Concentrations from the two applications add, since both the plume and the room equations are linear in the source. For applications of mass $m_j$ at times $t_j$, the emission rate is the superposition of their individual decays, where $\mathbb{1}$ is one once an application has been made and zero before.

\[q(t) = \sum_{j} \frac{m_j}{\tau} \, e^{-(t - t_j)/\tau} \, \mathbb{1}[t \geq t_j]\]
Morning sprays Midday sprays Total $D$ $K$ $O$ Feasible
3 0 3 0.40 0.11 0.00 No
4 0 4 0.48 0.15 0.01 No
6 0 6 0.59 0.23 0.01 No
2 1 3 0.44 0.10 0.00 No
2 2 4 0.53 0.15 0.00 Yes
3 1 4 0.53 0.15 0.00 Yes
3 2 5 0.60 0.19 0.01 Yes

Four sprays split as three and one, or two and two, achieve what five sprays applied at once achieve, with one spray fewer. The reason is visible in the decay model. A spray applied at seven in the morning spends most of its mass before the afternoon, and a spray applied at noon spends its mass when the end state still needs it. Holding at the end of the window, $t_1$, the emission rate that a dose $m_{\mathrm{req}}$ delivers at its start, $t_0$, requires a single application to be larger by the decay between them.

\[m_0 \geq m_{\mathrm{req}} \, e^{(t_1 - t_0)/\tau}\]

For the working day, from 0.5 h to 8 h, that factor is $e^{7.5/3} = 12$, almost all of which would be emitted in the morning as collateral. The four-push scenario, executed as a single application, is the wrong plan. Executed as a sequel, it is the smallest adequate plan for the full working day.

The sequel has a sustainment requirement, which is that the wearer carries a second platform to the midday decision point. That requirement is taken up in the section on application platforms.

Sensitivity

The calibrated threshold and four assumed parameters were varied one at a time. Each cell gives the smallest feasible single application of eau de parfum.

Case S1 S2 S3 S4 S5 S6
Base case None 5 1 1 6 Cost
Threshold tripled to 90 µg/m³ None None 2 2 None Cost
Threshold divided by three to 10 µg/m³ None None 1 None 2 Cost
Time constant 1.5 h None 5 1 1 6 Cost
Time constant 6 h None 5 1 1 6 Cost
Threshold spread 0.8 None 5 1 1 6 Cost
Threshold spread 1.6 None None 1 1 6 Cost
Plume spread 0.2 None None 1 1 3 Cost
Plume spread 0.45 None None 1 2 None Cost

None means no count from one to six is feasible, and Cost means every nonzero count violates the collateral constraint.

The results divide cleanly into two kinds. Structural results hold in every case. The shared office is infeasible, the elevator is a standing cost, and the interview needs one or two sprays. Dinner needs one or two in every case but one, and in that case, a threshold three times more sensitive than planned, even a single spray reaches the next table too often. Calibrated results move with the threshold and the plume spread, and the open-plan and outdoor answers belong to this kind. A reader should rely on the first kind and treat the second as an illustration of how the reasoning runs. The emission time constant barely matters at the level of the smallest feasible dose, which is reassuring given how crude the lumped model is.

The interview, where the sign of the objective is unknown

S3 was adjudicated as though detection by the interviewer were desirable, and the evidence does not establish that it is. Baron’s 1983 study of applicants wearing a pleasant scent is summarised in a later review by Sorokowska, Sorokowski and Havlíček as finding scented candidates rated especially favourably by female interviewers but not necessarily by male ones. In a follow-up, Baron found that male interviewers marked down applicants who combined scent with other positive cues such as smiling and eye contact, which he described as too much of a good thing.

The interview is therefore the one scenario in which detection may be a cost, and its plan has a branch. If the interviewer is known and the evidence favours detection, the plan is one spray. If the interviewer is unknown, the plan is zero. The difference between the two is a single spray, and the downside of the wrong branch is larger than the upside of the right one, because an interview is a single encounter with no sequel.

A second finding bears on every scenario. In a double-blind study by Roberts and colleagues, men given a fragranced antimicrobial deodorant rather than an identical inactive one reported higher self-confidence, and women watching video clips of them, who could not smell them, rated them more attractive. Photographs showed no difference, which locates the effect in behaviour. Part of the effect of a fragrance on others is mediated by the wearer and requires no receiver to detect anything. That part of the effect is fully delivered by the smallest dose the wearer knows has been applied, which is one more reason the adjudicated doses are small.

Placement

The conventional points

The conventional points can be stated with confidence only at the level of agreement among sources, because most of the grooming and fashion press that publishes them could not be retrieved in full for this article, and the sources that could be retrieved do not agree in detail. The Wikipedia article on perfume describes application to pulse points behind the ears, at the nape of the neck, under the armpits and on the insides of the wrists. Chanel’s guidance names pulse points such as the wrist and neck and offers clothing as an alternative that preserves the fragrance as composed. It adds that perfume can stain delicate fabrics and recommends applying it to the inside of a garment or its lining, which is the garment point the placement analysis below arrives at by a different route. The commonly repeated men’s plans place three sprays on the two sides of the neck and the chest, with a fourth on the nape or the wrists. The commonly repeated women’s plans place sprays on the wrists, the neck, behind the ears and on the décolletage, with the hair, the inner elbows and the backs of the knees as further options. Spray distances given in retail guidance range from about 10 cm to 20 cm.

The stated rationale is almost always warmth at the pulse points. No source located for this article measured a pulse-specific mechanism, and the temperature section above shows that the extremities, including the wrist, are cooler than the trunk rather than warmer. The pulse is the wrong mechanism for the wrist and an unnecessary one for the neck, whose advantage comes from proximity to the receiver’s nose.

The companion rule that the wrists must not be rubbed together because rubbing crushes the fragrance molecules has no physical basis in the form stated, since rubbing does not break covalent bonds. The only test located was informal. Victoria Frolova rubbed a fragrance on her wrists until the skin was pink and found after fifteen minutes that nobody could tell any dramatic difference. Rubbing warms and spreads the application, which by the temperature model should shorten the top notes slightly, and the effect is plausible, small and unmeasured.

What makes a point good

Five properties decide a point’s value, and each corresponds to a term in the models above.

  1. Temperature sets the emission rate and its exhaustion, through the Clausius and Clapeyron factor.
  2. Coverage by clothing slows emission, occludes some of the dose into the skin, and delays the start of projection.
  3. Geometry sets the distance to the receiver’s nose and whether the thermal plume carries the emission toward it.
  4. Attrition removes dose by contact, most of all by handwashing.
  5. Self-exposure sets the distance to the wearer’s own nose, and with it the speed of the adaptation that drives the reapplication spiral.

Attrition deserves an equation, because it is the property on which the wrist fails. Suppose each handwash removes a fraction $w$ of the dose remaining on the wrist, and the wearer washes every $\Delta t$ hours. The mass remaining on the wrist then decays continuously by emission and in steps by washing.

\[m(t) = m_0 \, e^{-t/\tau} \, (1 - w)^{\lfloor t / \Delta t \rfloor}\]

Averaged over the day, washing adds a loss rate to the emission rate, and the effective time constant $\tau_{\mathrm{eff}}$ is as follows.

\[\frac{1}{\tau_{\mathrm{eff}}} = \frac{1}{\tau} + \frac{-\ln(1 - w)}{\Delta t}\]

With the assumed values $w = 0.5$ and $\Delta t = 2$ h, the washing term is $0.693 / 2 = 0.35$ per hour against an emission term of 0.33 per hour, so $\tau_{\mathrm{eff}} = 1 / 0.68 = 1.5$ h. Handwashing halves the working life of a wrist application and sends the removed half down a drain instead of toward a receiver. The wrist is also the point most likely to transfer fragrance to food, paper and other people’s hands, and the point most often raised to the wearer’s own nose, which is the self-exposure pathway at its most direct.

The points assessed

The following table assesses each conventional point against the five properties. Entries are relative and qualitative except where an equation above supports them.

Point Temperature Coverage Geometry Attrition Self-exposure Assessment
Sides of the neck Trunk-warm Exposed Face height, in the plume Low High, about 0.2 m Strong projection, fast self-adaptation, sun-exposed
Base of the throat or sternum Trunk-warm Usually covered Below the face, in the plume Low Moderate Best single point
Nape of the neck Warm Exposed or under hair Behind the head Low Low Best second point, projects behind the wearer
Behind the ears Warm Exposed or under hair Face height Low High Equivalent to the neck, with a smaller target
Wrists Cooler Exposed Mobile High Very high when raised Weakest skin point
Inner elbows Intermediate Often covered Mobile Low Low Adequate, slow
Backs of the knees Intermediate Exposed in a skirt Low, in the plume Low Very low Adequate for a long, low-intensity trail
Underarms Warm Covered In the plume Interacts with deodorant Moderate Excluded for irritation and sensitisation
Hair Cool Exposed Face height, moves Low Moderate Long life, use a hair mist
Clothing Ambient Not applicable Wherever the garment is Removable Varies Longest life, staining risk, removable

The base of the throat or the sternum is the best single point. It is on the warm trunk, it sits in the thermal plume below the face so that its emission rises toward any receiver at face height, it suffers little attrition, and if a collar covers it, the emission is slowed and the self-exposure reduced. The nape is the best second point, because it projects behind the wearer, which is where the trail described as sillage is formed, and it is the warm point furthest from the wearer’s own nose. The wrist is the weakest skin point, cooler than the trunk, washed several times a day, and raised to the wearer’s own nose by the gesture used to check whether the fragrance is still there, which is the gesture that adapts the wearer fastest.

The adjudicated plans

The original question asked for the conventional points under the three-push and four-push scenarios, and the answer is set out below beside the adjudicated alternative. The conventional columns are a composite of commonly repeated advice rather than a quotation of any one source. The adjudicated plans are the same for any wearer, with variants for long hair and for an open neckline.

Plan Conventional, men Conventional, women Adjudicated
One push Chest One wrist or the neck Sternum or base of the throat
Two pushes Both sides of the neck Both wrists Sternum and nape
Three pushes Both sides of the neck and the chest Both wrists and the neck Sternum, nape and one garment point such as the inside of a collar or a scarf
Four pushes Both sides of the neck, the chest, and the nape or wrists Wrists, neck and behind the ears, or the hair Three in the morning at sternum, nape and garment, and one at midday at the sternum, by spray or rollerball

Three further rules complete the plans.

  • The scenario sets the count and the table sets the points. For dinner and the interview the adjudicated count is one, and the one-push plan applies regardless of habit. For the full working day in an open-plan office it is four, split as shown. In a small shared office or under a fragrance-free policy it is zero.
  • Long hair substitutes for the nape. A hair mist or a single spray from 20 cm onto the lengths, not the scalp, places dose on a cool, mobile, long-lived point that projects behind and around the wearer.
  • An open neckline moves the sternum point onto exposed skin. It then projects sooner and exhausts faster, and in daylight with a citrus-heavy product it is the point that photosensitivity concerns.

Whether the conventional points survive

The conventional neck points survive, for proximity, not pulse. The conventional chest point survives and is promoted to the first point. The conventional nape point survives and is promoted to the second. The conventional wrist points do not survive as skin points, on temperature, attrition and self-exposure together. The hair and garment points survive and are underused, since they are the only points with no skin exposure, and the garment is the only one that can be taken off.

Whether the Wearer’s Sex Changes the Answer

H3 asks whether the conventional difference between men’s and women’s points is a property of the wearer or of what the wearer is wearing. Setting the two conventional lists side by side and asking what each difference depends on gives the answer directly.

Conventional difference What it depends on
Décolletage for women, chest for men Neckline. It is the same anatomical point, covered or not
Hair for women Hair length
Backs of the knees for women Skirt length, which exposes or covers the point
Wrists emphasised for women No physical difference identified
Beard for some men Facial hair, a hair point at the worst possible self-exposure distance

Every difference with a physical basis resolves to clothing or hair. No source located for this article measured a difference in fragrance emission or longevity attributable to the wearer’s sex once those are held fixed, and claims about skin oiliness and longevity in the retail literature were not found in the peer-reviewed literature at all. H3 is supported.

The wearer is not without effect on emission. Hadjiefstathiou et al 2025, Exploring the impact of fragrance measured fragrance evaporation on the skin of several volunteers and found rates differing between individuals in ways explained by skin properties together with the molecules, using the device described by Hadjiefstathiou et al 2025, An innovative device for in vivo. The wearer term is real and it attaches to skin, not to sex, so it widens the emission model’s uncertainty without changing H3.

The receiver’s sex is a different matter, though a small one. In a meta-analysis of olfactory testing, Sorokowski and colleagues found women outperforming men in every domain, with effect sizes between 0.08 and 0.30 that the authors describe as weak, and a threshold effect of 0.16. Doty and Cameron’s review reaches a consistent conclusion. Read as a shift in the log threshold of $g$ standard deviations, and taking this article’s threshold spread $\sigma$ as the standard deviation, an effect of size $g$ scales the median threshold of the more sensitive group.

\[\frac{C_{50}^{\mathrm{women}}}{C_{50}^{\mathrm{men}}} \approx e^{-g \sigma}\]

With $g = 0.16$ and $\sigma = 1.2$, the ratio is $e^{-0.19} = 0.83$, so a female receiver’s median threshold is lower by a factor of about 1.2. That is a fifth of a spray per spray, below the resolution of the pump, and it does not change any adjudicated count. The conversion assumes that the test’s threshold units and this article’s share a spread, which is an inference and not a measurement.

Other Application Platforms

The spray count is a property of one platform. The other platforms in common use either have no natural unit of dose or carry so little aromatic material per unit that the spray-count framing breaks. Each is assessed here by what it changes in the dose and transport models.

Platform Carrier Dose control What it changes
Spray atomizer Ethanol Fixed volume per actuation The reference case
Rollerball Ethanol or oil Stroke length, poorly controlled Precise placement, no overspray, $\eta$ near one
Splash bottle Ethanol None Large and variable dose, usually of dilute product
Solid perfume Wax, oil or fat Fingertip load Low emission rate, intimate range only
Perfume oil or attar Oil, no ethanol Dab or stroke Slow emission, long life, short radius
Body mist Ethanol and water Fixed volume, low concentration Many sprays for one spray-equivalent
Hair mist Less ethanol, more water Fixed volume Formulated for the hair point
Aftershave Ethanol, astringents Palm load Low concentration on freshly shaved skin

The rollerball and the solid are the intimate-range platforms. Their deposition efficiency is near one, since nothing is lost to the air in the act of application, and their dose is small and concentrated at a single point. In the adjudication’s terms they reach S4 without the collateral that a spray brings, and they are the correct sequel platform for S2, since a midday stroke at one point delivers roughly the single spray the sequel requires without a plume in the office. Many rollerballs are an alcohol-based eau de parfum in different packaging, so the platform changes the deposition and not necessarily the product.

The solid perfume and the attar trade radius for longevity. An oil or wax carrier lowers the vapour pressure of the aromatic material dissolved in it, which in the emission model raises $\tau$. Because the detection radius scales as $\tau^{-1/2}$ at application, and its half-life scales as $\tau$, a carrier that changes the time constant from $\tau_1$ to $\tau_2$ trades one against the other.

\[\frac{r^{*}_2(0)}{r^{*}_1(0)} = \sqrt{\frac{\tau_1}{\tau_2}}, \qquad \frac{t_{1/2,2}^{(r)}}{t_{1/2,1}^{(r)}} = \frac{\tau_2}{\tau_1}\]

A carrier that triples the time constant shrinks the starting radius by $\sqrt{3}$, to 58 percent, and triples the time over which it decays. Attar is distilled into an oil base, traditionally sandalwood oil and now often liquid paraffin, with Kannauj in India as its historic centre.

Body mists invert the spray-count question. At about two percent aromatic content, a body mist delivers 0.13 spray-equivalents per actuation, so the conventional three-push of a body mist is 0.4 spray-equivalents, below the one-spray dose the adjudication found adequate for dinner. The count of a product at fraction $c$ that matches a required spray-equivalent dose inverts the spray-equivalent definition.

\[N = N_{\mathrm{eq}} \, \frac{c_{\mathrm{ref}}}{c}\]

Matching one spray-equivalent with a two percent body mist takes $0.15 / 0.02 = 7.5$ sprays, so a body mist used to the same end state takes about eight sprays, and the instruction on such products to spray liberally is consistent with the dose model and is not a marketing excess.

Aftershave is applied to freshly shaved skin, which the safety section excludes as a point for fine fragrance. Aftershave formulations include astringents and antiseptics for that reason and are low in aromatic content, so the conventional practice of following aftershave with a separate fragrance is a two-platform plan in which the aftershave contributes little to the end state.

Layering, the use of scented washes and lotions from the same line as the fragrance, adds dose at many points at once, and the claim that it extends longevity rests on retail guidance rather than measurement. The effect it certainly has is to add dose that the spray count does not record, so a layered plan should be adjudicated as a higher spray-equivalent.

Other Application Targets

Animals

The adjudicated course of action for applying human fragrance to an animal is zero. The reasons are physiological and they are not close. Domestic cats lack a functional form of the liver enzyme UGT1A6, as Court and Greenblatt established, which leaves them poorly able to glucuronidate phenolic compounds of the kind present in many essential oils. Veterinary guidance from VCA Animal Hospitals lists essential oils toxic to cats on that basis, and the American Society for the Prevention of Cruelty to Animals, or ASPCA, advises against essential-oil diffusers in homes with birds, whose respiratory systems are unusually sensitive to airborne compounds. Dogs present a receiver problem rather than a toxicity problem in the first instance. The usual claim that a dog’s nose is uniformly far more sensitive than a human’s is weaker than its popularity suggests, since McGann reviews evidence that humans outperform dogs for some odorants, but a dog’s nose is in any case the receiver nearest the application point, and the dog did not consent.

Where an animal is to be scented at all, veterinary guidance quoted by PetMD and by the American Kennel Club is to use a product made for the species, to keep it away from the face, eyes, ears and genitals, and not to mask an odour that may have a medical cause. In the terms of this article, that is a different product, a single point on the coat away from the receiver’s own nose, and an investigation of the reason for the application before it is made.

Bags, garments and textiles

A bag or garment is a target without skin chemistry, skin absorption or body heat. In the emission model its time constant is longer than skin’s, since the fabric surface is cooler, and in the transport model it lacks the thermal plume that carries scent upward from the body. It therefore holds fragrance longer and projects it less.

The conventional prohibitions are about materials, not effect. Luxury leather houses advise against direct contact between perfume and their leather goods, and silk and pale fabrics stain. The standard workaround is to scent an intermediate, such as a cotton pad, a scarf or a sachet placed inside the bag, and this is conventional practice rather than a sourced recommendation. A scarf is the most useful of these, because it is a garment point that can be removed, which makes it the only application point with an off switch.

Paper is the oldest textile-adjacent target in the record, from the perfumed valentines noted in the history section to the scented letter, and it is adjudicated as a one-receiver, intimate-range application with no collateral and no further analysis.

Rooms

A room is the one target for which area denial is the stated end state. The far-field equation of the transport section applies directly, with the source now a product designed to emit continuously. Room fragrance platforms include sprays, reed diffusers that evaporate from soaked reeds, electrically heated plug-in devices, candles and incense, and the burning of bakhoor, scented wood chips or blocks used in the Arabian Peninsula to perfume rooms, clothing and hair.

The steady state of a continuous room source $E$ in micrograms per hour, in a room of volume $V$ ventilated at $\lambda$ per hour, is the emission divided by the ventilation flow.

\[C_{\mathrm{room}}^{\infty} = \frac{E}{\lambda V}\]

A reed diffuser emitting 20 mg per hour of aromatic material into a 40 m³ living room at half an air change per hour holds $20{,}000 / (0.5 \times 40) = 1{,}000$ µg/m³, thirty-three times the median detection threshold used throughout and above its planning value for too strong. The emission figure is an assumption for illustration, and the conclusion it supports is relative. The approach to that steady state from a fresh start is governed by the ventilation alone.

\[C_{\mathrm{room}}(t) = C_{\mathrm{room}}^{\infty} \left( 1 - e^{-\lambda t} \right)\]

At half an air change per hour the room reaches 95 percent of its steady state after $3 / \lambda = 6$ h, so a diffuser placed in the morning has not yet shown its full effect by the afternoon, and a household that judges it by the first hour will overprovision it. The steady state is inversely proportional to ventilation, so a room fragrance product tuned for a draughty room is overpowering in a sealed one, and closing a window doubles the concentration as surely as doubling the product does.

Two cautions specific to rooms carry over from the safety section. Room products emit continuously for hours or weeks, so their contribution to the indoor terpene and ozone chemistry described by Nazaroff and Weschler is much larger than that of a personal application. And every occupant of a room is a receiver, including the animals discussed above, for whom the restraint on diffusers is the operative one.

A car is a room with a volume of about 3 m³. By the far-field equation, the wearer’s own morning application reaches room-regime concentrations in a closed car within minutes, and any room product added to it is applied to the smallest volume considered here.

Safety

The restraints stated at the outset are given content here. Each is a limit that no end state justifies exceeding.

Contact allergy

Fragrance ingredients are among the commonest causes of allergic contact dermatitis. The European Commission’s Scientific Committee on Consumer Safety, or SCCS, concluded in 2012 that one to three percent of the general European population is allergic to fragrance ingredients, and it classified 82 substances as established contact allergens in humans, 54 single chemicals and 28 natural extracts. The fragrance study of the European Dermato-Epidemiology Network, or EDEN, which patch tested 3,119 people drawn from the general population of five European countries, found reactions to fragrance mix I in 2.6 percent and to fragrance mix II in 1.9 percent, and gave a conservative estimate of fragrance allergy of 1.9 percent.

Regulation follows the same evidence. Commission Regulation 2023/1545 of the European Union added 56 fragrance allergens to the 24 already subject to individual labelling in cosmetic products, with labelling required above 0.001 percent in leave-on products and 0.01 percent in rinse-off products. The industry’s own instrument is the set of standards maintained by the International Fragrance Association, or IFRA, which prohibit, restrict or specify the purity of individual materials. For materials that cause sensitisation, the limits are derived by quantitative risk assessment, or QRA, revised as QRA2 by Api and colleagues to account for aggregate exposure from several products used together, which is the regulatory form of the observation that layering adds dose the spray count does not record.

Spray distance and dose per unit area

The induction of skin sensitisation depends principally on the dose per unit area of skin rather than on the total dose, as Kimber, Dearman and Basketter review, except when the exposed area falls below a critical size. Spray distance therefore matters for safety in a way it does not for projection. An atomizer delivers a roughly conical spray of half-angle $\theta$, so at a distance $d$ the footprint has radius $d \tan \theta$ and one actuation spreads its deposited mass over that footprint at a mean areal dose $\mu$.

\[\mu = \frac{v_s \, \rho \, c \, \eta}{\pi \, d^2 \tan^2 \theta}\]

With an assumed half-angle of 20 degrees, one actuation of eau de parfum at 10 cm covers 41.6 cm² at a mean of $8{,}610 / 41.6 = 207$ µg/cm² of aromatic material. At 15 cm it covers 93.6 cm² at 92 µg/cm², and at 20 cm 166.5 cm² at 52 µg/cm². Doubling the spray distance quarters the areal dose. The calculation holds the deposition efficiency fixed, which overstates the dose at the greater distances, since more of the spray drifts away from the target, and both errors run in the safe direction. The spray distance in conventional advice is usually justified by even coverage, and the better reason is the inverse square of the distance.

The operational consequence for the application plan is narrow and firm. Sensitisation is cumulative and largely irreversible, so the application plan minimises the dose placed on skin whenever skin is not required by the end state. A wearer who has reacted to a fragrance stops wearing it on skin, and the clothing and hair points in the placement section are the fallback and not a workaround. Broken, irritated or freshly shaved skin is excluded as an application point, because a compromised barrier increases both irritation and the likelihood of sensitisation.

Photosensitivity

Bergamot oil contains furocoumarins, principally bergapten, which under ultraviolet light cause a phototoxic reaction and lasting pigmentation known as berloque dermatitis. In open photopatch tests of bergamot oil and bergapten, Zaynoun, Johnson and Frain-Bell found the phototoxic reaction affected by the vehicle, the concentration of ethanol in it, the skin site, the interval between application and irradiation, the hydration of the skin and its pigmentation, which means that an ethanol-based fragrance on a sun-exposed point is close to the tested condition. IFRA restricts furocoumarin content in leave-on products for this reason, as its furocoumarin update describes, so a compliant modern product presents a low risk. The residual guidance is that the sides of the neck and the décolletage are sun-exposed points, and a wearer using an older, unregulated or home-blended product containing citrus oils should move the application under clothing for an outdoor scenario in daylight.

Eyes, mucous membranes and ingestion

Fine fragrance is mostly ethanol. The National Capital Poison Center gives typical alcohol contents of about ninety percent for eau de parfum and sixty percent for eau de cologne, and warns that in a child ingested alcohol can lower blood sugar to dangerous levels. Bottles are therefore stored as a household chemical is stored, out of reach of children, and the spray is never directed toward the face, the eyes or the mouth, including the wearer’s own. Spraying from 10 to 15 cm at the neck keeps the plume clear of the eyes only if the head is turned away, and the placement section assumes that it is.

Flammability

Ethanol has a flash point of about 13 °C according to the Pocket Guide to Chemical Hazards of the United States National Institute for Occupational Safety and Health, or NIOSH, and its vapour is flammable in air between 3.3 and 19 percent by volume. A freshly sprayed point carries flammable vapour for the seconds before the ethanol evaporates. Fragrance is not applied near an open flame, a lit cigarette or a gas hob, and a pressurised aerosol can is additionally kept away from heat.

The adjudication’s collateral constraint is not a matter of taste alone. A survey of 1,136 adults in the United States by Steinemann found that 34.7 percent reported health problems, including respiratory, migraine and skin effects, when exposed to fragranced consumer products. The figure rests on self-report from an online panel and measures reported sensitivity rather than diagnosed effect, so it should not be read as a prevalence of harm. It is nonetheless large enough that an unintended receiver must be presumed sensitive until shown otherwise, and it has been replicated in other countries by the same method, at 19.9 percent of a representative German sample in the survey reported by Klaschka 2020 and 14.6 percent of a national sample in Saudi Arabia by Alrasheed et al 2021. Inhalation of the spray itself is a smaller concern for a pump atomizer than for an aerosol can. Berrada-Gomez et al 2023 found that pump sprays released on average 0.5 percent of their particles in the respirable range, against 15.25 percent for propellant sprays, so the receiver of a pump-applied fragrance inhales its vapour rather than its droplets.

Workplaces have responded with written policy. The United States Centers for Disease Control and Prevention, or CDC, adopted an indoor environmental quality policy in 2009 asking employees to be as fragrance-free as possible, though the text survives only as quoted by a secondary source and no current copy on the agency’s own site was located. The United States Access Board, the federal agency responsible for accessibility guidelines, recommends in its indoor environmental quality guidance that a fragrance-free policy include restrictions on perfume, cologne and other scented personal care products used by employees, visitors and other occupants. In the United States the Job Accommodation Network lists fragrance sensitivity among conditions for which employers make accommodations such as relocation or reduced exposure. A wearer in a workplace with a fragrance-free policy adopts the zero-spray course of action, which the adjudication already identified as the only one that satisfies S1 and S6.

Fragrance also takes part in indoor chemistry. Terpenes common in fragrances react with ozone indoors to form formaldehyde and secondary organic aerosol, as reviewed by Nazaroff and Weschler and measured by Singer and colleagues. The quantities from a personal application are small next to those from room fragrance products, which is why the room is treated with more caution below.

Materials

Ethanol and fragrance oils stain silk and pale fabrics and can mark leather. Pearls are damaged by acids and by cosmetics, hairspray and perfume, as the Gemological Institute of America notes, and the jeweller’s rule that pearls go on last and come off first follows from that. Fragrance is applied and allowed to dry before jewellery is put on.

Transport

Air travel imposes a sustainment constraint of its own. In the United States the Transportation Security Administration’s liquids rule limits carry-on liquids to containers of 100 mL or 3.4 ounces in a single quart-sized bag, so the sequel platform for a travel day is a small atomizer or a solid.

Adjacent Offensive Applications

The same delivery physics serves purposes this article does not adjudicate, and the boundary is drawn here so that its location is explicit.

Pepper spray delivers an inflammatory agent, oleoresin capsicum, by the same pressurised aerosol mechanism used by some fragrance and deodorant products. Its strength is best described by the content of capsaicin and related capsaicinoids rather than by the percentage of oleoresin capsicum or a Scoville rating, because, as Reilly, Crouch and Yost found, commercial products are not standardised for capsaicinoid content even when labelled by heat rating. The Wikipedia article on pepper spray summarises the same point. Bear spray is a related product registered in the United States by the Environmental Protection Agency, or EPA, as a pesticide, and interagency guidance advises carrying only EPA-registered products. A registered label states its active ingredient as capsaicin and related capsaicinoids at 2.0 percent, the measure that the oleoresin percentage obscures. In the United Kingdom such sprays fall within section 5 of the Firearms Act 1968, in its paragraph on noxious substances, which prohibits weapons designed for the discharge of any noxious liquid, gas or other thing, though the statute does not name pepper spray as such. Malodorants, odours selected to be offensive to nearly everyone, were the subject of research for the United States Department of Defense reported in 2002 and of later military small-business research topics.

These products share with fragrance an aerosol platform, a plume and a receiver. They differ in that the receiver’s consent is absent by design, which places them outside every restraint this article operates under, and in that the end state is incapacitation or dispersal instead of detection. Collateral and overkill have their ordinary meanings in that literature as well. A full analysis of offensive applications is out of scope, and nothing in the adjudication above transfers to them. Two points are stated so that the boundary is not crossed by accident. A fragrance is never sprayed at another person, which falls under the restraint on consent. And a fragrance applied at the overkill end of the adjudicated range is not an offensive application, merely a poorly planned one.

A Survey of the Contemporary Literature

The sections above used the literature to argue. This one reports it, including the parts that bear against the argument and the parts that bear on nothing in it. The question the survey asks is what the published literature knows about fragrance as something applied to a target and perceived by others, which is wider than the question of where to spray and narrower than the chemistry of perfume.

How the survey was built

The bibliographic index Crossref was queried on 3 October 2026 with 115 queries covering perfume release and performance, fragrance on skin and textiles, odour perception and thresholds, olfactory adaptation, individual differences in smell, fragrance allergy and safety, fragranced products in indoor air, fragrance sensitivity, the social and psychological effects of fragrance, the human thermal plume and near-field exposure, consumer spray exposure, essential oils and animals, irritant sprays, the history of perfumery and fragrance products. The queries returned 15,061 distinct records.

A record was admitted on its title alone by a gate written for this article. Several words in this subject are homonyms across large literatures, and the gate refuses titles that carry them in their other senses. Aroma reaches wine, coffee and food chemistry, adaptation reaches climate science, plume reaches volcanology, spray reaches agriculture and coating technology, and olfactory research is dominated by insect and rodent neuroscience. Four bodies of work were excluded deliberately rather than by accident, and a reader should know that they exist. These are the literature on smell loss after coronavirus infection, which is large and concerns the receiver’s illness and not the application, environmental odour nuisance from farms and treatment works, electronic noses, and food flavour. The gate was tuned against random samples of what it kept and what it dropped, drawn with the seeds 20261003, 7741 and 31415 and read in full, and against named guard titles that it must keep or refuse, which it does. Book reviews, peer-review reports, retail listings and one-word titles were refused as carrying no claim. After removing duplicate registrations of the same work, 2,541 works were admitted, each assigned to the first of sixteen clusters whose pattern its title matches.

The surveyed literature is recent. Of the 2,498 works with a publication year, the median year is 2014, 1,192 or 47.7 percent date from 2015 or later, and 518 date from before 2000. 100 carry the year 2026 and therefore postdate this article’s editorial date, as do an unknown number of works from late 2025, which the bibliographic year cannot separate. They are included because a survey of the contemporary literature, written a year after the date it carries, is obliged to report what that year added.

Every admitted work is cited in its cluster’s row below, so the survey is checkable against the reference list, and the counts are verified against the rows mechanically. Admission by title is not a judgement of quality, and the rows mix peer-reviewed research with conference abstracts, preprints and trade articles. The works the prose below discusses by content were read in abstract. Those whose abstracts could not be retrieved are named for their titles only, and the prose says so where it does.

What the literature establishes, and where it is moving

The engineering literature has moved from modelling evaporation to measuring it on people. The perfume engineering programme that supplied the odour-value framework used above continues in the review by Rodrigues et al 2021. Its newer empirical arm measures release from real skin. Hadjiefstathiou et al 2025, An innovative device for in vivo built a device that samples the air above a perfume applied to volunteers’ forearms and to model surfaces, using a perfume of eight fragrance molecules in ethanol, and Hadjiefstathiou et al 2025, Exploring the impact of fragrance used it to show that evaporation rates differ between individuals in ways explained jointly by skin properties and by the molecules themselves. That finding bears directly on H3. It identifies a wearer-specific term in the emission model, and it attaches that term to skin properties rather than to sex. At the slow end of the evaporation curve, Malhiac et al 2026 found that a single headspace extraction does not recover all of a base note deposited on a blotter, and measured residual retention of 8 to 12 percent after eight hours in the presence of a longevity technology. Berthier et al 2023 measured the evaporation kinetics of individual materials in a model perfume and showed a class of fixatives slowing the evaporation of materials with volatilities below 5,000 µg/L in both fine fragrance and eau de toilette. These studies support the lumped emission model’s direction and expose its simplification, because they show that a perfume is a set of pools with very different time constants, and that some of the slowest pool is never emitted at all within a day.

The delivery literature is the largest part of the engineering cluster and mostly concerns textiles and household products. Microcapsules that release fragrance over a day are now routine, for example the silica capsules of Yeom et al 2024, designed to sustain release for up to 24 hours after topical application, and reviews such as Taghilou 2026 catalogue biodegradable carriers and encapsulation as the route to longevity. Dallay et al 2023 reviews how fragrance partitions in skin-care emulsions and borrows from the food literature on aroma release from emulsions. None of this literature addresses spray count or placement, and the absence is the reason they had to be modelled here.

The emission literature has found that fragrance matters to air quality out of proportion to its mass. Hurley et al 2021 characterised eleven commercial fragrance mixtures and reported that fragrance compounds made up less than half of their mass, that terpenes and terpenoids were only about a tenth of the liquid by mass but accounted for nearly all of the emitted reactivity, and that 20 to 40 percent of the potential hydroxyl reactivity does not evaporate quickly enough to matter for local air quality. Two of those findings bear on this article’s planning values. If the mixtures studied resemble the oil in a fine fragrance, the odorous fraction of what is not ethanol is smaller than the class labels suggest, and the share that does not evaporate within hours is a modelled quantity rather than a hypothetical one.

The indoor-air literature confirms the ventilation term of the far-field model in field measurements. Cheng et al 2023 sampled volatile organic compounds from reed diffusers in bathrooms and recorded significantly higher concentrations at lower air change rates. Lee et al 2024, Effect of spraying air freshener sprayed air fresheners in vehicle cabins for under a minute and measured total volatile organic compounds peaking at 364.3 µg/m³ at the front seat, the same order of magnitude as the car calculation above, though for a different product and a larger dose. Kim et al 2024 found that electrically warming scented candles raised indoor monoterpene levels by factors of 16 to 30 on average, and Yun et al 2025 measured fine particles from candles remaining elevated three and six metres from the flame. Rádis-Baptista 2023 reviews the health effects attributed to fragranced personal care and household products, and the risks of scented candles are reviewed by Singh et al 2023, which is known here only by its title.

The perception literature has refined measurement and has begun to predict perception from receptors. Threshold testing with standardised pens is now routine and the cluster is dominated by it. Ren et al 2025 reviews the variability of odour detection thresholds and their influence on building-material odour assessment, which is the problem the log-normal threshold distribution above represents, and is cited by title alone, its abstract being unavailable. Fuseda et al 2025 showed that a modified six-point intensity scale yields ratings on an absolute rather than a relative perceptual scale. Ihara et al 2025 predicted perceptual similarity among eugenol-like odorants from the activation profiles of six olfactory receptors. Receivers also vary within themselves. Bontempi et al 2025 found odours rated more intense in the luteal than the follicular phase of the menstrual cycle, and Nikolaou et al 2025 associated long-term exposure to traffic-related air pollution with impaired odour identification in a population study of 3,059 people.

The adaptation literature now supplies the time scale this article had to assume, and it supports the assumption. Pierce and Simons 2018 delivered linalool and vanillin continuously and found perceived intensity of orthonasal vanillin significantly reduced at five minutes and at ten. Hintschich et al 2024 found odour thresholds already significantly elevated after ten minutes of continuous exposure to phenylethyl alcohol, more so after two hours, and more so in older participants. At the scale of weeks, Mignot et al 2020 exposed participants to an odour at home for two weeks and reported raised thresholds that recovered fully within a week of the exposure ending, with no difference between younger and older adults. That recovery is faster than the two weeks reported by Dalton and Wysocki, and the difference between the two studies is a disagreement in the literature rather than a settled value. Li et al 2023, Patients with olfactory loss exhi found pronounced adaptation in patients with olfactory loss, and Mignot et al 2021 could not establish a clear peripheral mechanism in recordings from the olfactory epithelium, which is consistent with adaptation arising at least partly centrally.

One study tests the wearer directly, and it is the closest thing in the literature to a measurement of this article’s restraint. Beekman et al 2022 asked whether sensory panellists should refrain from wearing perfume, tested nineteen participants under no fragrance, an amount judged about right, and an excessive amount, and found odour threshold and discrimination significantly worse in both perfumed conditions. Wearing even a moderate amount of perfume degraded the wearer’s own sense of smell. The article argued that the wearer is the least reliable sensor from adaptation alone, and this result shows the degradation extending to odours other than the fragrance worn.

The literature on individual differences supports the receiver model and adds that specific anosmia can be trained, briefly. Gillmeister et al 2025, Investigating plasticity of the o screened 335 people for specific anosmia to androstenone, benzyl salicylate, bacdanol or maltol, trained 77 of them for two months, after which sensitivity to the odours they had been unable to smell improved, but that nine of ten participants followed up after 19 months had lost the gain for androstenone. Gillmeister et al 2025, Olfactory training in specific an examined the same training in relation to variants of the receptor gene OR7D4. Benzyl salicylate and bacdanol are perfumery materials, so a fragrance can contain components that a measurable fraction of receivers cannot smell. At the population scale, Suzuki et al 2026 estimated chronic self-reported olfactory dysfunction in Japan at 1.3 percent, rising with age, and Mai et al 2026 recorded the decline with age at the psychophysical, mucosal and cortical levels.

The allergy literature reports high and stable rates among patients, and is moving toward animal-free potency testing. Botvid et al 2024 systematically reviewed 84 studies of European dermatitis patients and found sensitisation to fragrance mix I in 6.81 percent and to fragrance mix II in 3.64 percent, with no clear trend over time and substantial rates among children. These are rates among patients referred for patch testing, higher than the general-population rates in the safety section and not comparable with them. Sukakul et al 2024 reviews patch testing for fragrance allergy, Celeiro 2026 reviews the analytical methods regulators now need to enforce the expanded allergen labelling, and Donthamsetty et al 2024 reports an in vitro assay predicting the no-expected-sensitisation-induction levels on which quantitative risk assessment rests. Api 2026 summarises six decades of the Research Institute for Fragrance Materials, whose individual ingredient safety assessments make up a large share of this cluster’s row.

The sensitivity literature has replicated high self-reported rates across countries, and its policy arm is growing. Klaschka 2020 reports a representative German survey in which 19.9 percent of the population described adverse effects from fragranced products. Half of the fragrance-sensitive had at some time avoided a place because of fragrance, and half of them also used perfume to feel more attractive. Alrasheed et al 2021 found self-reported perfume sensitivity in 14.6 percent of a national sample in Saudi Arabia, with asthma and the use of counterfeit perfume as risk factors. Comparisons of international prevalence by Steinemann 2019, International prevalence of fragr and of fragranced against fragrance-free products by Nematollahi et al 2024 are cited for their titles, since neither abstract was available. All of these are self-report surveys, and the caution the safety section attaches to Steinemann’s figure applies to each.

The social literature is dominated by ambient scent and chemosignals, and its strongest recent result is again on the wearer’s side. Dai et al 2026 paired strangers to share happy events and sharers wearing a pleasant fragrance reported more positive emotion and a stronger sense of belonging, with corresponding differences in cortical functional connectivity. Together with Roberts and colleagues, this places a measurable part of the social effect of fragrance in the person wearing it. Lv et al 2025 measured emotional responses to fragrance with behavioural paradigms that agreed with electroencephalographic measures, and Feng et al 2025 studied floral, fruity and forest scents against physiological markers of fatigue in office workers. The office studies are the ambient-scent literature’s version of the room regime above, in which the scent is deliberately a property of the space and every occupant is its receiver.

The airflow literature confirms the thermal plume’s role and supplies the exposure models this article used. Zong et al 2022 reviews the human thermal plume and reports that it carries particles from the floor to the breathing zone at concentrations up to four times the ambient, which supports the article’s treatment of low application points as feeding a rising plume. Sun et al 2021 notes that in calm indoor air most inhaled air comes from the boundary layer through which the plume flows, and Gena et al 2020 measured the plume of a heated manikin by schlieren velocimetry. The two-zone near-field and far-field model built from first principles above is standard in occupational hygiene, where Abattan et al 2021 reviewed 446 predicted-to-measured concentration ratios across 21 studies, and in cosmetic safety, where Steiling et al 2025 recommends one-box and two-box models for spray exposure.

The spray-exposure literature finds that pump atomizers release very little respirable material. Berrada-Gomez et al 2023 measured the droplet size distributions of 78 cosmetic sprays and showed that pump sprays released on average 0.5 percent of particles in the respirable range, against 15.25 percent for propellant sprays. For a fine-fragrance pump the inhalation route is therefore the vapour, not the droplet. Lee et al 2024, Emission characteristics of volat measured volatile organic compounds at one and three metres from 47 consumer sprays with aromatic deodorants the highest emitters, and Dai et al 2025 measured particle emissions from sprays applied to the face and neck which proved strongly dependent on nozzle design.

The animal literature is small, practical and consistent with the article’s zero-dose answer. Bates 2018 warns that a few drops of pure tea tree oil applied to a pet’s skin can cause clinical signs and that deaths have occurred, and Sisubalan et al 2023 reviews the uses and safety of essential oils in pets.

The irritant-spray literature, which this article declares out of scope, is reported here only so that its size is known. It is clinical, forensic and operational. Semple et al 2020 reviews injuries and deaths near oleoresin capsicum deployment, Forrester and Holloway 2021 estimates 34,582 pepper-spray injuries treated in United States emergency departments from 2000 to 2020, Boivin and Tanguay 2020 found in 1,019 police interventions that the most concentrated sprays acted faster but more often required decontamination, and Wilder et al 2022 found bear spray effective against polar bears in 18 of 19 incidents, with wind affecting performance in one. The last two results are the irritant literature’s versions of this article’s dose curve and wind term, which is a structural observation and not a transfer of anything here to that domain.

The historical literature is reaching the earliest perfumers through their texts. Song 2025 studies the Middle Assyrian perfume recipes from the Temple of Aššur, the period and the tradition of the perfumer Tapputi, and reads them as craft knowledge passing from practice into writing. Burger et al 2019 surveys the history of extracting natural fragrance materials, and a cultural history of the perfume vaporiser by Wicky 2024 is named here for its title, no abstract having been obtainable.

What the survey changes in this article

Four results change the article and one supports it more than it expected.

  • The adaptation time constant is no longer purely an assumption. Significant reductions in intensity at five minutes and in threshold at ten bracket the planning value of five minutes from both sides, and the reapplication spiral rests on measurement as well as on mechanism.
  • The wearer’s degradation is measured. Perfume worn in moderate amounts lowered the wearer’s threshold and discrimination performance.
  • Wearers differ in emission, by skin rather than by sex. H3 stands, and the wearer term it excluded has been located in skin properties.
  • The lumped emission model’s residue is real. Part of a fragrance does not evaporate within a working day from a blotter or in a model, which lowers the effective deposited mass and moves every count in the adjudication slightly upward.
  • The far-field and near-field models are the standard exposure models of two neighbouring disciplines, which the transport section reached independently and which supports their use.

Three gaps remain. No study located in the survey measures detection by other people as a function of spray count. None compares application points on the body by emission or by detection. And none measures the conventional advice on spray distance, rubbing or moisturising. The three questions the original prompt rested on are therefore the three the literature has not asked.

The clusters

Each row lists every admitted work in its cluster, newest first.

Perfume release, evaporation, longevity and controlled delivery

How a fragrance leaves the surface it is applied to, measured, modelled and engineered, from evaporation profiles on skin to fixatives, microcapsules and textile finishes.

161 works. [Alhazmi et al 2026] [Cheng 2026] [D. Deshmukh and Agrawal 2026] [Gholami et al 2026] [Gonçalves et al 2026] [Hua et al 2026] [Murad et al 2026] [Schember et al 2026] [Singh et al 2026] [Taghilou 2026] [Yang et al 2026, Gender Sensing and Personalized F] [Chen et al 2025, Structure and release function of] [Chen et al 2025, The Preservation and Development] [Deneththi et al 2025, Enhanced fragrance release on cot] [Deneththi et al 2025, Investigate the Effect of Crossli] [Deng 2025] [Hadjiefstathiou et al 2025, An innovative device for in vivo] [Hadjiefstathiou et al 2025, Exploring the impact of fragrance] [Hadjiefstathiou et al 2025, Revealing the role of surface che] [Hua et al 2025] [Kongyang et al 2025] [Ospina et al 2025] [Zhao et al 2025] [Zhou 2025] [Zhou et al 2025] [Bera et al 2024] [Ng et al 2024] [Nurfitria et al 2024] [Sumant et al 2024] [Yeom et al 2024] [Zhang 2024] [Cheng et al 2023] [Gu et al 2023] [Morinaga and Wada 2023] [Szajnecki and Nowak 2023] [Beekman et al 2022] [Chen et al 2022] [Costa et al 2022] [Trachsel et al 2022] [Yeom et al 2022] [Zhao et al 2022] [Hurley et al 2021] [Kert et al 2021] [Liu et al 2021, In silico prediction of fragrance] [Mamusa et al 2021] [Pithanthanakul et al 2021] [Rodrigues et al 2021] [Shen et al 2021] [Tchakalova et al 2021] [Du et al 2020] [Maulana et al 2020] [Mayr and Breu 2020] [Niu et al 2020] [Stasse et al 2020] [Wei et al 2020] [Almeida et al 2019] [Badmaanyambuu et al 2019] [Li et al 2019, Front Cover Optimization of heads] [Li et al 2019, Optimization of headspace for GC] [Stasse et al 2019] [Watanabe 2019] [Zhang et al 2019] [Zhao et al 2019] [Berton et al 2018] [Chappuis et al 2018] [Chen et al 2018] [Liu et al 2018] [Nematollahi et al 2018] [Bandyopadhyay and Das 2017] [Berton et al 2017] [Chakraborty 2017] [Günay et al 2017] [Herrmann 2017] [Morinaga et al 2017] [Penfold et al 2017] [Pérez-Outeiral et al 2017] [Shi et al 2017] [Starkenmann et al 2017] [Griesbeck et al 2016] [Günay et al 2016] [Lee et al 2016] [New encapsulation method paves 2016] [Ye et al 2016] [Zhao et al 2016] [Cortial et al 2015] [Khanna et al 2015] [Popadyuk et al 2015] [Tekin et al 2015] [He et al 2014] [Hofmeister et al 2014] [Indradas et al 2014] [Kuhnt et al 2014] [Li et al 2014] [Liu and Hayashi 2014] [Ramamoorthy and Rajiv 2014] [Tchakalova et al 2014] [ter Burg et al 2014] [Blesic et al 2013] [Camerlo et al 2013] [Li et al 2013] [Perfume Engineering 2013] [Teixeira et al 2013, Classification of Perfumes-Perfum] [Teixeira et al 2013, Diffusion and performance of frag] [Teixeira et al 2013, Performance of Perfumes] [Trachsel et al 2013] [Wang et al 2013] [Xiao et al 2013] [Friberg and Aikens 2012] [Jensen et al 2012, Facial allergic contact dermatiti] [Marteau et al 2012] [Peña et al 2012] [Rihn et al 2012] [Tzhayik et al 2012] [Hu et al 2011] [Lama and Zhou 2011] [Masuck et al 2011, Estimation of dermal and oral exp] [Son and Lee 2011] [Binks et al 2010] [Friberg and Aikens 2010] [Ge et al 2010] [Laudamiel 2010] [Masuck et al 2010] [Sansukcharearnpon et al 2010] [Gilpin et al 2009] [Teixeira et al 2009, The diffusion of perfume mixtures] [Theisinger et al 2009] [Fragrance delivery system for 2008] [Ge et al 2008] [Wang et al 2008] [Gomes et al 2007] [Friberg 2006] [Levrand and Herrmann 2006] [Mata and Rodrigues 2006] [Liu et al 2005] [Wang and Chen 2005] [Targeted hair/perfume delivery patented 2004] [Bothe et al 2003] [Frérot et al 2003] [Procter and Gamble obtains 2003] [Saiyasombati and Kasting 2003] [Ikemoto et al 2002] [International Procter and Gamble 2002] [Sorokina et al 2002] [Quellet et al 2001] [Schwarzenbach and Bertschi 2001] [Stora et al 2001] [rgen Bertram et al 2001] [Liu and Wene 2000] [Zhang et al 2000] [Aikens et al 1999] [Friberg and Yin 1999] [Hamdan et al 1999] [Barbe et al 1998] [Friberg et al 1997] [Vuilleumier et al 1995] [Escher and Oliveros 1994] [Blakeway and Seu-Salerno 1983] [Perfumery Essential Oils and 1970] [Hulbert and Feben 1941] [Hadjiefstathiou] [Phookchaub]

Fragrance on skin and hair, and regional skin temperature

Fragrance materials on and through the skin and hair, and the distribution of skin temperature across the body that sets their evaporation.

30 works. [Korman et al 2026] [Dallay et al 2023] [Iman et al 2021] [Nanyan 2019] [Hermanns et al 2018] [Paqueron 2017] [Cho et al 2016] [Fernandes et al 2016] [Compositions for delivering perfume 2015] [Schilder et al 2015] [Shen et al 2014] [Nahm et al 2009] [Schnuch et al 2009] [Brain et al 2007] [Dermal Absorption of Fragrance 2007] [Fukusaki et al 2007] [Werdehausen et al 2007] [Stevens et al 2006] [Mookerjee et al 2005] [Stevens et al 2005, 272. Skin temperature during regi] [Stevens et al 2005, Skin temperature during regional] [Percutaneous Absorption of Fragrances 2002] [Hood et al 1996] [Karlsson et al 1996] [Karlsson et al 1995] [Qualls et al 1993] [Brutsaert and Sugita 1991] [Bronaugh et al 1990] [Directional effects of skin 1981] [Largen et al 1978]

Odour thresholds, intensity and perception

How odour is detected, scaled and judged, from threshold measurement and its variability to intensity scales, mixtures and the prediction of perception from structure.

467 works. 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Olfactory Perception During 2004] [Rezendes et al 2004] [Sakai et al 2004] [Genetics of Olfactory Perception 2003] [Kay et al 2003] [Madany Mamlouk et al 2003] [Navarrete-Palacios et al 2003] [Odor Perception in Neurodegenerative 2003] [Psychophysical Measurement of Human 2003] [Doty 2002] [Gillette 2002] [Hermans and Baeyens 2002] [Hudson and Distel 2002] [Chen 2001] [Distel 2001] [Elsner 2001] [Herz and von Clef 2001] [Rothney et al 2001] [Stevenson 2001] [Dalton 2000] [Eli 2000] [Olsson 2000] [Sobel 2000] [Zatorre et al 2000] [Herz 1999] [Ikeda et al 1999] [Lehrner 1999] [Odour Discrimination 1999] [Recent advances in mechanisms 1999] [Hau and Connell 1998] [Liden et al 1998] [Livermore and Laing 1998] [Alaoui-Ismaïli et al 1997] [Chen 1997] [Doty 1997] [Engen and Engen 1997] [Hummel et al 1997] [Lawless 1997] [Lucchini et al 1997] [Mitsuda et al 1997] [Dalton 1996] [Devillers et al 1996] [Livermore and Laing 1996] [Rospars et al 1996] [Tamura et al 1996] [Jehl et al 1995] [Lehrner 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Olfactory adaptation and habituation

The loss of sensitivity during and after exposure, over seconds, minutes and weeks, which is the mechanism behind the wearer’s unreliability.

84 works. [Jiang et al 2027] [Bourassa et al 2026] [Takahashi et al 2026] [Tong et al 2026] [Bourassa et al 2025] [Wu and Zhang 2025] [Birkett and Nikolaev 2024] [Hintschich et al 2024] [Ledgerwood et al 2024] [Fukumoto et al 2023] [Olfactory Adaptation 2022] [Mignot et al 2021] [Xiao et al 2021] [Zou et al 2021] [Fallon et al 2020] [Kim et al 2020, Odor habituation can modulate ver] [Laffon et al 2020] [Mignot et al 2020] [Abbasi et al 2019] [Kim et al 2019] [Kumazaki et al 2019] [Teşileanu et al 2019] [Janjua and Hirsch 2018] [Pierce and Simons 2018] [Tesileanu et al 2018] [Sinding et al 2017] [Antunes et al 2014] [Gul et al 2014] [Matsubasa et al 2014] [Ramic-Brkic and Chalmers 2014] [Juang et al 2013] [Sadanandappa et al 2013] [Sudhakaran et al 2013] [De Palo et al 2012] [Keith and Smith 2011] [McCann et al 2011] [Stephan et al 2011] [Funato et al 2009] [Hayden et al 2009] [Lecoq et al 2009] [Linster et al 2009] [Olfactory Adaptation 2009] [Yamada et al 2009] [Ohba and Yamanaka 2008] [Shea et al 2008] [Tonosaki 2008] [Kadowaki et al 2007] [Linster et al 2007] [Philpott et al 2007] [Toda et al 2007] [Kadohisa and Wilson 2006] [Zimmerman 2006] [Olfactory Cross-adaptation Not a 2005] [Yadon and Wilson 2005] [Adelman and Herson 2004] [Miyahara et al 2004] [Gutierrez-Osuna and Gutierrez-Galvez 2003] [Takeuchi et al 2003] [Kawai 2002] [Kelling et al 2002] [Bradley et al 2001] [Reisert 2000] [Zufall 2000] [Leinders-Zufall et al 1999] [Reisert and Matthews 1999] [Kurahashi and Menini 1997] [Dalton and Wysocki 1996] [Gomez and Atema 1994] [Hoshika 1994] [Moore 1994] [Cain and Polak 1992] [Köster and de Wijk 1991] [King and Hall 1990] [Schild et al 1990] [Stevens et al 1989] [Baylin and Moulton 1979] [Rovee 1972] [Stone et al 1972] [Berglund et al 1971] [Pryor et al 1970] [Steinmetz et al 1970] [Komatu 1960] [Moncrieff 1956] [Ente]

Individual differences in smell

Differences between receivers by sex, age, genotype and health, including specific anosmia and the clinical literature on smell loss.

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Fragrance allergy, phototoxicity and ingredient safety

Contact allergy to fragrance and its patch testing, berloque dermatitis and furocoumarins, and the ingredient-by-ingredient safety assessment literature.

454 works. [Api 2026] [Bruze et al 2026] [Celeiro 2026] [Correction to ‘Contact Sensitization 2026] [Evans et al 2026] [Lee and Api 2026] [Mangır and Özkaya 2026] [McIntyre and Lio 2026] [Sari et al 2026] [Soriano 2026] [Api et al 2025] [Determining a point of 2025] [Ghafur 2025, Balancing Fragrance and Patient S] [Kim and Park 2025] [Kim et al 2025] [Lavelle et al 2025] [Natsch 2025] [Natsch et al 2025] [Ruiz Sánchez et al 2025] [Uraga et al 2025] [Api et al 2024, RIFM fragrance ingredient safety assessment, 1,3,5-undecatriene, CAS Registry Number 16356-11-9] [Api et al 2024, RIFM fragrance ingredient safety assessment, 2,4,5-trimethylthiazole, CAS Registry Number 13623-11-5] [Api et al 2024, RIFM fragrance ingredient safety assessment, 2-methyl-5-phenylpentanol, CAS Registry Number 25634-93-9] [Api et al 2024, RIFM fragrance ingredient safety assessment, 2-p-tolylethanol, CAS registry number 699-02-5] [Api et al 2024, RIFM fragrance ingredient safety assessment, 3- methylthio hexyl acetate, CAS 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Update to RIFM fragrance ingredient safety assessment, 2-ethylbutyric acid, CAS Registry Number 88-09-5] [Api et al 2024, Update to RIFM fragrance ingredient safety assessment, butyric acid, CAS Registry Number 107-92-6] [Api et al 2024, Update to RIFM fragrance ingredient safety assessment, eucalyptol, CAS Registry Number 470-82-6] [Api et al 2024, Update to RIFM fragrance ingredient safety assessment, α-propylphenethyl alcohol, CAS registry number 705-73-7] [Botvid et al 2024] [Donthamsetty et al 2024] [Gökalp Satıcı et al 2024] [Mazur et al 2024] [Rodriguez 2024] [S Sayapathi and Rowther 2024] [Sukakul et al 2024] [Velastegui Hernández et al 2024] [Özkaya and Toprak 2024] [Api et al 2023, RIFM fragrance ingredient safety assessment, 2,3,3-trimethylindanone, CAS registry number 54440-17-4] [Api et al 2023, RIFM fragrance ingredient safety assessment, estragole, CAS registry number 140-67-0] [Api et al 2023, RIFM fragrance ingredient safety assessment, ± ethyl 3-mercaptobutyrate, CAS Registry Number 156472-94-5] [Api et al 2023, Update to RIFM fragrance ingredie] [Botvid et al 2023] [Ghadiri et al 2023, CD03 Contact sensitization to she] [Ghadiri et al 2023, Contact sensitisation to shellac] [Pérès et al 2023] [Raison-Peyron et al 2023] [Amornruk et al 2022] [Api et al 2022, RIFM fragrance ingredient safety assessment, - - R -α-phellandrene, CAS Registry Number 4221-98-1] [Api et al 2022, RIFM fragrance ingredient safety assessment, 1,3-dimethyl-3-butenyl salicylate, CAS Registry Number 80118-10-1] [Api et al 2022, RIFM fragrance ingredient safety assessment, 3,7-dimethyloct-1-en-3-ol, CAS Registry Number 18479-49-7] [Api et al 2022, RIFM fragrance ingredient safety assessment, 8-nonenal, CAS Registry number 39770-04-2] [Api et al 2022, RIFM fragrance ingredient safety assessment, benzoic acid, CAS Registry Number 65-85-0] [Api et al 2022, RIFM fragrance ingredient safety assessment, cinnamic acid, CAS Registry Number 621-82-9] [Bruze et al 2022] [Jagodich et al 2022] [Kim et al 2022] [Krijl et al 2022] [Lee et al 2022, Assessment of the skin sensitizat] [Lee et al 2022, Derivation of the no expected sen] [Na et al 2022] [Stingeni et al 2022] [Sukakul et al 2022] [Yi et al 2022] [Zhong et al 2022] [Özkaya and Kılıç Sayar 2022] [Özkaya et al 2022] [Api et al 2021, RIFM fragrance ingredient safety assessment, 3-octanol, CAS Registry Number 589-98-0] [Api et al 2021, RIFM fragrance ingredient safety assessment, cinnamyl formate, CAS Registry Number 104-65-4] [Api et al 2021, RIFM fragrance ingredient safety assessment, cyclohexadecanone, CAS Registry Number 2550-52-9] [Api et al 2021, RIFM fragrance ingredient safety assessment, p-menthan-2-one, CAS Registry number 499-70-7] [Chen et al 2021] [Geier et al 2021] [Gopinath et al 2021] [Liu and Zenobi 2021] [Lu et al 2021] [Marmgren et al 2021] [Mays et al 2021] [Pawelec and Wielgomas 2021] [Pilkington 2021] [Roh and Cheng 2021] [Schubert et al 2021] [de Groot 2021, Contact allergy to and allergic c] [de Groot 2021, Monographs of fragrance chemicals] [van Amerongen et al 2021] [Api et al 2020] [Api et al 2020, RIFM fragrance ingredient safety assessment, methyl 3,4,5,6-tetrahydro-7H-azepin-2-yl ether, CAS Registry] [Api et al 2020, RIFM fragrance ingredient safety assessment, myrcenol, CAS Registry Number 543-39-5] [Bruze et al 2020] [Couteau et al 2020] [Kullberg et al 2020] [Na et al 2020] [Orgaz et al 2020] [Remy et al 2020] [Sanchez and Katta 2020] [Sanchez et al 2020] [Sukakul et al 2020] [Towle et al 2020] [Api et al 2019, RIFM fragrance ingredient safety assessment, 1-cyclohexene-1-acetic acid, CAS Registry Number 18294-87-6] [Api et al 2019, RIFM fragrance ingredient safety assessment, 3-heptanone, CAS Registry Number 106-35-4] [Api et al 2019, RIFM fragrance ingredient safety assessment, anisyl phenylacetate, CAS Registry Number 102-17-0] [Api et al 2019, RIFM fragrance ingredient safety assessment, m-dimethoxybenzene, CAS Registry Number 151-10-0] [Api et al 2019, RIFM fragrance ingredient safety assessment, myrtenol, CAS Registry Number 515-00-4] [Bennike et al 2019, Optimal patch test concentration] [Bennike et al 2019, Quality of life and disease sever] [Bruze et al 2019] [Fragrances Incorporating Fragrance Mix 2019] [Maillard et al 2019] [Periyasamy et al 2019] [Schneller-Pavelescu et al 2019] [Api et al 2018, RIFM fragrance ingredient safety assessment Dimethyl succinate, CAS Registry Number 106-65-0] [Api et al 2018, RIFM fragrance ingredient safety assessment β-patchoulene, CAS Registry Number 514-51-2] [Api et al 2018, RIFM fragrance ingredient safety assessment, 3,3,5-trimethylcyclohexaneacetic acid, CAS Registry Number] [Api et al 2018, RIFM fragrance ingredient safety assessment, acetal, CAS Registry Number 105-57-7] [Api et al 2018, RIFM fragrance ingredient safety assessment, ethyl 2-methyl-3-pentenoate, CAS Registry Number 1617-23-8] [Avonto et al 2018] [Cascais 2018] [Gaspari 2018] [Goebel et al 2018] [Goossens 2018] [Hamann et al 2018] [Soo Lim et al 2018] [Uter 2018] [Wang et al 2018, Front Cover Rapid and green deter] [Wieck et al 2018] [Api et al 2017, RIFM FRAGRANCE INGREDIENT SAFETY] [Api et al 2017, RIFM Fragrance Ingredient Safety] [Api et al 2017, RIFM fragrance ingredient safety assessment, 2-tert-butylcyclohexanol, CAS Registry Number 13491-79-7] [Api et al 2017, RIFM fragrance ingredient safety assessment, 3,12-Tridecadienenitrile CAS Registry Number 134769-33-8] [Api et al 2017, RIFM fragrance ingredient safety assessment, 4-Carvomenthenol, CAS Registry Number 562-74-3] [Api et al 2017, RIFM fragrance ingredient safety assessment, 5-Ethylidenebicyclo 2.2.1 hept-2-yl propionate, CAS Registry] [Api et al 2017, RIFM fragrance ingredient safety assessment, Citronellyl nitrile, CAS Registry Number 51566-62-2] [Api et al 2017, RIFM fragrance ingredient safety assessment, Isoamyl butyrate, CAS Registry Number 106-27-4] [Api et al 2017, RIFM fragrance ingredient safety assessment, Isoamyl octanoate, CAS Registry Number 2035-99-6] [Api et al 2017, RIFM fragrance ingredient safety assessment, Isobornyl 2-methylpropionate, CAS Registry Number 85586-67-0] [Api et al 2017, RIFM fragrance ingredient safety assessment, Methylcyclooctyl carbonate, CAS Registry Number 61699-38-5] [Api et al 2017, RIFM fragrance ingredient safety assessment, benzenepropanol, a,ß-dimethyl-, CAS Registry Number 56836-93-2] [Api et al 2017, RIFM fragrance ingredient safety assessment, cuminyl nitrile, CAS Registry Number 13816-33-6] [Api et al 2017, RIFM fragrance ingredient safety assessment, isoamyl acetate, CAS Registry Number 123-92-2] [Api et al 2017, RIFM fragrance ingredient safety assessment, isoamyl alcohol CAS Registry Number 123-51-3] [Api et al 2017, RIFM fragrance ingredient safety assessment, isoamyl formate, CAS Registry Number 110-45-2] [Api et al 2017, RIFM fragrance ingredient safety assessment, isoamyl hexanoate, CAS Registry Number 2198-61-0] [Api et al 2017, RIFM fragrance ingredient safety assessment, isoamyl propionate, CAS Registry Number 105-68-0] [Api et al 2017, RIFM fragrance ingredient safety assessment, isobornyl isovalerate, CAS registry number 7779-73-9] [Api et al 2017, RIFM fragrance ingredient safety assessment, isodecyl alcohol, CAS registry number 25339-17-7] [Api et al 2017, RIFM fragrance ingredient safety assessment, isononyl propionate, CAS Registry Number 65155-45-5] [Api et al 2017, RIFM fragrance ingredient safety assessment, isotridecyl acetate, CAS registry number 69103-23-7] [Api et al 2017, RIFM fragrance ingredient safety assessment, methyl anthranilate, CAS Registry Number 134-20-3] [Api et al 2017, RIFM fragrance ingredient safety assessment, p-methoxybenzonitrile, CAS Registry Number 874-90-8] [Api et al 2017, RIFM fragrance ingredient safety assessment, β-Guaiene, CAS Registry Number 88-84-6] [Belhassen et al 2017] [Bennike et al 2017, Fragrance contact allergens in 55] [Bennike et al 2017, Non-mix fragrances are top sensit] [Bennike et al 2017, Trends in contact allergy to frag] [Lee et al 2017] [Mowitz et al 2017] [Perper et al 2017] [Wang et al 2017] [White 2017] [Adamowicz et al 2016] [Api et al 2016, RIFM fragrance ingredient safety assessment, 1,3,3-trimethyl-2-norbornanyl acetate, CAS registry number] [Api et al 2016, RIFM fragrance ingredient safety assessment, 1- 1,2,3,4-tetrahydro-4,4-dimethyl-1-naphthyl propan-1-one, CAS] [Api et al 2016, RIFM fragrance ingredient safety assessment, 1- 3,3-dimethylcyclohexyl pent-4-en-1-one, CAS Registry Number] [Api et al 2016, RIFM fragrance ingredient safety assessment, 2-Hydroxy-α,α,4-trimethylcyclohexanemethanol, CAS Registry] [Api et al 2016, RIFM fragrance ingredient safety assessment, 2-ethyl-1-butanol, CAS Registry Number 97-95-0] [Api et al 2016, RIFM fragrance ingredient safety assessment, 2-ethyl-1-hexanol, CAS registry number 104-76-7] [Api et al 2016, RIFM fragrance ingredient safety assessment, 2-methylundecanol, CAS Registry Number 10522-26-6] [Api et al 2016, RIFM fragrance ingredient safety assessment, 3,7-dimethyl-1,6-nonadien-3-ol, CAS Registry Number 10339-55-6] [Api et al 2016, RIFM fragrance ingredient safety assessment, 4-methylbenzyl acetate, CAS Registry Number 2216-45-7] [Api et al 2016, RIFM fragrance ingredient safety assessment, Benzyl propionate, CAS Registry Number 122-63-4] [Api et al 2016, RIFM fragrance ingredient safety assessment, Eugenol, CAS Registry Number 97-53-0] [Api et al 2016, RIFM fragrance ingredient safety assessment, Isopropylphenylbutanal, CAS Registry Number 125109-85-5] [Api et al 2016, RIFM fragrance ingredient safety assessment, Isopulegol, CAS Registry Number 89-79-2] [Api et al 2016, RIFM fragrance ingredient safety assessment, benzyl butyrate, CAS Registry Number 103-37-7] [Api et al 2016, RIFM fragrance ingredient safety assessment, benzyl isobutyrate, CAS Registry Number 103-28-6] [Api et al 2016, RIFM fragrance ingredient safety assessment, ethylene brassylate, CAS Registry Number 105-95-3] [Api et al 2016, RIFM fragrance ingredient safety assessment, isobornyl propionate, CAS Registry Number 2756-56-1] [Api et al 2016, RIFM fragrance ingredient safety assessment, isoeugenol, CAS Registry Number 97-54-1] [Api et al 2016, RIFM fragrance ingredient safety assessment, l-linalool, CAS Registry Number 126-91-0] [Api et al 2016, RIFM fragrance ingredient safety assessment, linalyl benzoate, CAS Registry Number 126-64-7] [Api et al 2016, RIFM fragrance ingredient safety assessment, linalyl cinnamate, CAS Registry Number 78-37-5] [Api et al 2016, RIFM fragrance ingredient safety assessment, p-Isopropylbenzyl acetate, CAS Registry Number 59230-57-8] [Api et al 2016, RIFM fragrance ingredient safety assessment, α-Ionone, CAS Registry Number 127-41-3] [Api et al 2016, RIFM fragrance ingredient safety assessment, α-Methylbenzyl acetate, CAS Registry Number 93-92-5] [Basketter and Safford 2016] [Bråred Christensson et al 2016, Fragrance Allergens, Overview wit] [Bråred Christensson et al 2016, Oxidized limonene and oxidized li] [Di Sotto and Mazzanti 2016] [Hamann 2016] [Meding and Järvholm 2016] [Norris et al 2016] [Sabroe et al 2016] [Shibuta et al 2016] [Vejanurug et al 2016] [Api et al 2015, RIFM fragrance ingredient safety assessment, 2,6-Dimethyl-5-heptenal, CAS Registry Number 106-72-9] [Api et al 2015, RIFM fragrance ingredient safety assessment, 2-methyl-3-buten-2-ol, CAS Registry Number 115-18-4] [Api et al 2015, RIFM fragrance ingredient safety assessment, 2E,6Z -Nona-2,6-dien-1-ol, CAS registry number 28069-72-9] [Api et al 2015, RIFM fragrance ingredient safety assessment, Benzyl acetate, CAS Registry Number 140-11-4] [Api et al 2015, RIFM fragrance ingredient safety assessment, Benzyl alcohol, CAS Registry Number 100-51-6] [Api et al 2015, RIFM fragrance ingredient safety assessment, Fenchyl alcohol, CAS registry number 1632-73-1] [Api et al 2015, RIFM fragrance ingredient safety assessment, Isoborneol, CAS Registry Number 124-76-5] [Api et al 2015, RIFM fragrance ingredient safety assessment, Linalool, CAS registry number 78-70-6] [Api et al 2015, RIFM fragrance ingredient safety assessment, Linalyl acetate, CAS Registry Number 115-95-7] [Api et al 2015, RIFM fragrance ingredient safety assessment, Linalyl hexanoate, CAS Registry Number 7779-23-9] [Api et al 2015, RIFM fragrance ingredient safety assessment, Linalyl isovalerate, CAS Registry Number 1118-27-0] [Api et al 2015, RIFM fragrance ingredient safety assessment, Z -2-penten-1-ol, CAS Registry Number 1576-95-0] [Api et al 2015, RIFM fragrance ingredient safety assessment, allyl cyclohexyloxy acetate, CAS registry number 68901-15-5] [Api et al 2015, RIFM fragrance ingredient safety assessment, allyl phenylacetate, CAS registry number 1797-74-6] [Api et al 2015, RIFM fragrance ingredient safety assessment, borneol, CAS registry number 507-70-0] [Api et al 2015, RIFM fragrance ingredient safety assessment, ethyl anthranilate, CAS registry number 87-25-2] [Api et al 2015, RIFM fragrance ingredient safety assessment, isoamyl salicylate, CAS registry number 87-20-7] [Api et al 2015, RIFM fragrance ingredient safety assessment, isophytol, CAS Registry Number 505-32-8] [Api et al 2015, RIFM fragrance ingredient safety assessment, l-Borneol, CAS registry number 464-45-9] [Api et al 2015, RIFM fragrance ingredient safety assessment, linalyl isobutyrate, CAS registry number 78-35-3] [Api et al 2015, RIFM fragrance ingredient safety assessment, methyl dihydrojasmonate, CAS registry number 24851-98-7] [Api et al 2015, RIFM fragrance ingredient safety assessment, α-Irone, CAS registry number 79-69-6] [Api et al 2015, RIFM fragrance ingredient safety assessment, α-amylcinnamaldehyde, CAS registry number 122-40-7] [Api et al 2015, RIFM fragrance ingredient safety assessment, α-butylcinnamaldehyde, CAS Registry Number 7492-44-6] [Basketter and Kimber 2015] [Basketter et al 2015] [Celeiro et al 2015] [Desmedt et al 2015] [Diepgen et al 2015] [Divišová et al 2015] [Geier 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Fragranced products in indoor air

Emissions from air fresheners, diffusers, candles, incense and other fragranced products, and their secondary chemistry indoors.

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Fragrance sensitivity, chemical intolerance and fragrance-free policy

Self-reported sensitivity to fragrance, multiple chemical sensitivity, fragrance as a trigger of asthma and migraine, and the policies written in response.

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Fragrance, body odour and their social and emotional effects

What fragrance and body odour do to mood, attractiveness, impression formation and social interaction, including human chemosignals and ambient scent.

236 works. 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The human thermal plume, the breathing zone and near-field exposure

The airflow a body generates around itself and the near-field and far-field models used to predict exposure close to a source.

55 works. [Cernei et al 2026] [Vanama et al 2026] [Xu et al 2025, Convective heat transfer coeffici] [Chen et al 2024] [Liu et al 2024] [Park et al 2024] [Pourfattah et al 2024] [Castellini et al 2023] [Nicas 2023] [Salamone et al 2023] [Zong et al 2023] [Hossain et al 2022] [Liu et al 2022, Bacteria-carrying particles diffu] [Liu et al 2022, Effect of human thermal plume and] [Sankaran et al 2022] [Zong et al 2022] [Abattan et al 2021] [Jamin et al 2021] [Koivisto et al 2021] [Ma et al 2021] [Sun et al 2021] [Zhang et al 2021] [Gena et al 2020] [Vianello et al 2019] [Wang et al 2018, Corrigendum to “Chaotic behavior] [Arnold et al 2017, Evaluating well-mixed room and ne] [Arnold et al 2017, Evaluation of the well mixed room] [Ivanov and Mijorski 2017] [Licina et al 2017] [Fantke et al 2016] [Cheng and Lin 2015] [Koelblen and Bogdan 2015] [Liu et al 2015, Effect of Thermal Plume on Person] [Liu et al 2015, Numerical Investigation of the Un] [Melikov 2015] [Feyli et al 2014] [Evaluation of Recommended REACH 2012] [Salmanzadeh et al 2012] [Method 11 Real-Time Breathing 2010] [Bayesian Modeling of Exposure 2009] [Marr et al 2007] [Melikov and Kaczmarczyk 2007] [Craven and Settles 2006] [Guffey and El-Nahas 2006, 40. Effects of Heating, Posture] [Guffey and El-Nahas 2006, 41. Effects of Breathing, a Wig] [Guffey and El-Sotouhy 2006] [General Ventilation and the 2003] [Assad 1999] [Bradley et al 1995] [D’Amore and Tufano 1991] [Uchiyama and Toyokura 1982] [El-Sotouhy] [Elnahas] [Fetouri] [Jafari]

Consumer and cosmetic spray exposure

What a spray product releases into the air its user and bystanders breathe, by droplet size, distance and product type.

18 works. [Dai et al 2025] [Steiling et al 2025] [Lee et al 2024, Emission characteristics of volat] [Berrada-Gomez et al 2023] [Sørli et al 2022] [Jung et al 2021] [Calcaterra et al 2020] [Yang et al 2019] [Park et al 2018, Comparison of modeled estimates o] [Park et al 2017] [Riebeling et al 2015] [Nazarenko et al 2011] [Rothe et al 2011] [Ravichandran et al 2009] [Ravichandran and Philominathan 2008] [Standard Practice to Indicate Direction 1997] [Li and Hopke 1994] [Practice for Labeling Cans]

Essential oils and companion animals

The toxicity of essential oils and fragrance materials to cats, dogs and other animals kept indoors.

14 works. [Radulović and Mladenović 2026] [Tadee et al 2024] [Sisubalan et al 2023] [Bates 2018] [Buckle 2015] [Khan et al 2014] [van Beusekom et al 2013] [Sharma and Tiwari 2012] [Naeini A. 2011] [Buckle 2003] [Miyazawa et al 2003] [Tisserand 1996] [Moss 1994] [Seawrlght 1993]

Irritant sprays and malodorants

Pepper spray, bear spray, riot-control agents and malodorants, which share the aerosol platform and are out of scope beyond this survey.

102 works. [Hajdu et al 2025] [Miller et al 2025] [Pepitone 2025] [Patowary et al 2024] [Maples 2023] [Logrado et al 2022] [Pearce and Mundell 2022] [Shah et al 2022] [Torsten Huschbeck 2022] [Weber et al 2022] [Wilder et al 2022] [Wittern and Gaur 2022] [Ye et al 2022] [Borusiewicz et al 2021] [Forrester and Holloway 2021] [Lechner et al 2021] [Thottempudi et al 2021] [Boivin and Tanguay 2020] [Craig Bettenhausen 2020] [Daft 2020] [Haller 2020] [Semple et al 2020] [Silva 2020] [Smith et al 2020] [Strybel and Kumar 2020] [Svendsen et al 2020] [Linder and Lacy 2019] [Miller 2019] [Miller et al 2019] [Mörén et al 2019] [Oliveira Junior et al 2019] [Goodman 2018] [Oztas 2018] [Patowary et al 2018] [Stopyra et al 2018] [Bertilsson et al 2017] [Haar et al 2017] [Brandl and Stroshine 2016] [Subcutaneous Emphysema and Pneumomediastinum 2016] [Efeoğlu et al 2015] [Huntington 2015] [Yeung and Tang 2015] [Zhu et al 2015] [Don’t Forget the Bear 2014] [Kearney et al 2014] [Officers Under Attack-The Thin 2014] [Ozer 2014] [Rasier et al 2014] [Voegeli and Baenninger 2014] [Sweeting 2013] [Cumiskey and Brewster 2012] [Hambling 2012] [Kumar et al 2012] [Maira and Sze 2012] [Shimada et al 2012] [Utine and Durak 2012] [Warren 2012] [Gerber et al 2011] [Persson 2011] [Pfaff and Steiner 2011] [Kaminski and Adang 2010] [Oh et al 2010] [Oke et al 2010] [Pepper Spray 2010] [Barley 2009] [Barry et al 2008] [DeSesa et al 2008] [Smith et al 2008] [White V and Presser 2008] [Fatah et al 2007] [Adang et al 2006] [Hennessy 2006] [Pershing et al 2005] [Prophets, Protests, and Pepper 2005] [Adang and Mensink 2004] [Gillis et al 2003] [Chan et al 2002] [Hand and Chotiner 2002] [Reilly et al 2002] [Epstein and Majmudar 2001] [Harrison et al 2001] [Miller 2001] [Reilly et al 2001] [Brown et al 2000] [Smith and Alpert 2000] [Zollman et al 2000] [Kaminski et al 1999] [Busker and van Helden 1998] [Kaminski et al 1998] [Temte 1998] [Giardino 1997] [Kelly 1997] [Lumb and Friday 1997] [Morabito and Doerner 1997] [Billmire et al 1996] [Miller 1996] [Watson et al 1996] [George et al 1995] [Heck 1995] [Steffee et al 1995] [Noguchi et al 1984] [Prophets, Protests, and Pepper]

The history of perfume and perfumery

Perfume from Mesopotamian recipes and Egyptian unguents to the vaporiser and the modern industry.

52 works. [Bydoon and Abd El-Baset 2026] [David 2025] [Wicky 2024] [Cole 2023] [McMullen and Dell’Acqua 2023] [Ager 2022] [Algrain 2022] [Corrente 2022] [Maxwell 2022] [History of the Perfume 2020] [Burger et al 2019] [Murray 2019] [Celik et al 2018] [Kaviraj 2016] [Gandaloyeva 2015] [Sato and Tamura 2015] [Voudouri and Tesseromatis 2015] [Harvey 2014] [Vanhaesebrouck 2014] [McHUGH 2013] [Milner 2013] [Wannaruemon et al 2013] [Boyson 2012] [The Ephemeral History of 2012] [Dugan 2011] [de Nicolaï 2008] [Bährle-Rapp 2007, Eau de Cologne] [Gasarian 2007] [Kakhidze 2007] [Pybus 2006, The history of aroma chemistry an] [Eau de Cologne 2004, Eau de Cologne - Futurismus] [Eau de Cologne 2004, Eau de Cologne eklatant] [van de Pol 2003] [Pybus et al 1999, The history of aroma chemistry an] [Timeless Beauty Ancient Perfume 1995] [Shanks 1993] [Ohloff 1992] [Frances Kennett, History of 1977] [Winter 1942] [Winter 1932] [The Eau de Cologne 1930] [Colmers 1927] [Gohrbandt 1927] [Gohrbandt 1926] [Conard 1908] [Odorographia a Natural History 1892] [The Preparation of Good 1892] [EAU DE Cologne Tippling 1889] [Reid 1879] [Eau de Cologne 1874] [On the Manufacture of 1852] [Pires Latge]

Fragrance products, platforms and the industry

Fine fragrance, solid perfume, attar, aftershave and body mist as products, and the industry that designs and sells them.

108 works. [Bansal 2026] [Ghafur 2026] [Sanjaya et al 2026] [Shneider 2026, From Talk to Tags Privacy-Preserv] [Shneider 2026, Privacy-Preserving Shelf-Edge Fee] [Shneider 2026, The Language of the Shelf A Taxon] [Ganta.Manasa et al 2025] [Iqbal et al 2025] [Karamore et al 2025] [Lohar 2025] [Norman 2025] [Sujono et al 2025] [Hendrik Hermawan et al 2024] [MacCarthy et al 2024] [Sawant and Jain 2024] [Yunus et al 2024] [Abishekh S. Gawande et al 2023] [Berthier et al 2023] [Francis et al 2023] [Mensing 2023, Big and Small Moments of Modern P] [Mensing 2023, Insider Knowledge Perfume Industr] [Mensing 2023, Insider Knowledge Perfumery] [Mensing 2023, Stationary Perfumery in Change] [Tigerlily Perfumery, 973 Valencia 2023] [aftershave, n. and adj 2023] [Dwijayanty and S.A., MBA., Ph.D. 2022] [Gavira et al 2022] [H. Taher et al 2022] [Randal and Stanton 2022] [Velinov 2022] [Barwich and Xu 2021] [Butnariu 2021] [Ibrahim et al 2021] [Pal et al 2021] [Ponda et al 2021] [Septiyanti et al 2021] [Professionalizing Perfumery Eugène Rimmel 2020] [Zawisławska 2019] [Vanilla in Perfumery and 2018] [Perfume Bottle 2017] [Wuyts et al 2017] [Biotechnology in Perfumery 2016] [Chen and Huang 2016] [D. Jawad Al-Bayati 2016] [Guillemin 2016, § 3 Behind the Scenes of Perfumer] [Srinivasan 2015] [Castello 2014] [Perfume Bottle 2014] [Bergamot and Its 2013] [Gattefosse 2013] [Okoronkwo et al 2013] [Teixeira et al 2013, A Product Engineering Approach in] [The Perfume Industry 2013] [Jung 2011, Comparison of Different Perfumery] [Jung 2011, Perfumery on the Arabian Peninsul] [Buccellato 2010] [Sell 2006, Ingredients for the modern perfum] [Narula 2005] [Narula 2004] [Smith 2004] [Hoecht and Trott 2002] [Introduction to perfumery 2002] [Perfumery and cosmetic products 2002] [Perfumery uses of lavender 2002] [Rose-scented geranium’ a Pelargonium 2002] [Lecoffre 2001] [Attar of Roses 1997] [Jellinek 1997, Perfume creation and odor sensati] [Jellinek 1997, Perfumery and eroticism] [Jellinek 1997, Soap perfumery] [Jellinek 1997, Technical progress and fashion in] [Jellinek 1996] [Perfumery Practice and Principles 1996] [Sell 1996] [Diploma in perfumery 1995] [Perfumery practice and principles 1995] [Chakrabarty et al 1994] [Ellena 1994] [Funesti 1994] [Rotton 1994] [Roudnitska 1994] [Poucher 1993] [Greenhalgh 1992] [Hornfeldt 1992] [Izumi 1991] [Dodd 1988] [WHEN Alcoholics Drink Aftershave 1986] [Moskowitz 1978] [Van Ketel 1978] [Poucher 1974, A dictionary of the raw materials] [Poucher 1973] [How A Computer Service 1965] [Crow 1964] [Crow 1960] [Levey 1960] [Jellinek 1950] [Wight 1942] [Piskur 1938] [The Raw Materials of 1922] [The Perfumery Industry in 1913] [Atkinson 1910] [Seguin 1899] [Perfumes and Perfumery 1894] [Wrenn 1883] [Levi 1879] [Perfumes and Perfumery 1863] [The London Exhibition-Perfumery 1862] [Hofmann 1852]

Perfume and fragrance outside the clusters above

Works whose titles concern perfume or fragrance without falling into a narrower cluster, including cultural, literary and analytical studies.

316 works. [Aryadi and Pidada 2026] [Bertomeu-Sánchez 2026] [Longing for Luxury Perfume 2026] [Malhiac et al 2026] [Matricciani 2026] [Perfume/sweet 2026] [Spence et al 2026] [Sutia and Hendri 2026] [Sánchez-López et al 2026] [Troiano 2026] [Vijay 2026] [Villas Bôas Camargo 2026] [Audette et al 2025] [Dandi et al 2025] [Feng et al 2025] [Ghafur 2025, The Future of Fragrance Personali] [Lecourt and Antoniotti 2025] [Nam and Kim 2025] [Rembulan and Sanjaya 2025] [Sagala and Anggusti 2025] [Song 2025] [Sujatha Lavudiya et al 2025] [Vilhelkar and Momin 2025] [Chiamaka Frances and Nwakuche 2024] [Cunniffe et al 2024] [Droulers et al 2024] [Gell 2024] [King 2024] [Miss Nirmal Vrushali S. et al 2024] [Mufarokhah et al 2024] [Risky et al 2024] [Songsathitmetha et al 2024] [Souza 2024] [Spence et al 2024] [Steele 2024] [Syafriani and Suendri 2024] [Wenxia Li et al 2024] [van Gelder 2024] [氣味擬像與身體隱喻:羚羊(Gazelle)、香水收集者(The Perfume Collector)和香水(Das Parfum)對比研究 2024] [Bumke 2023] [Cairolli 2023] [Chandra and Soelistyo 2023] [Eichhorn et al 2023] [Givaudan and LanzaTech to 2023] [Jung 2023] [Kolenčíková 2023] [Krueger 2023] [Manina and Forlani 2023] [Mensing 2023, Perfumes in Change] [Mensing 2023, Scent Online Storytelling and Dig] [Mensing 2023, The Research of the Fragrance Eff] [Mesz et al 2023] [Pradhan et al 2023] [Prasad and Veera 2023] [Rodrigues and Albergaria 2023] [Silva 2023] [Whitman 2023, Clover and Hay Perfume] [Whitman 2023, Sundown Perfume Quail-Notes The H] [Death by Perfume 2022, 8. Death by Perfume] [Death by Perfume 2022, Death by Perfume] [Givaudan and LanzaTech announce 2022] [Hemamalini and Giri Dev 2022] [Impossible Flowers and Building 2022, 11 Impossible Flowers and Buildin] [Impossible Flowers and Building 2022, Impossible Flowers and Building a] [Lin et al 2022, Investigate the Direct Photodegra] [Lin et al 2022, Investigations on the direct phot] [Marques 2022] [Moyse Ferreira 2022] [Patrícia Garcia Leal and Ezequias Oliveira Lira 2022] [Perfume Notes 2022, 10 Perfume Notes] [Perfume Notes 2022, Perfume Notes] [Picturing Perfume 2022, 3. Picturing Perfume] [Picturing Perfume 2022, Picturing Perfume] [Urano et al 2022] [Whittaker 2022] [Yamashita et al 2022] [Yoon and Choi 2022] [von Dürckheim et al 2022] [Aneetta VJ and Amsamani S 2021] [Biocatalytic Directed Cationic Cyclization 2021] [Guć et al 2021] [Neto and Ogasawara 2021] [Northfield 2021] [Renaldi et al 2021] [Riad et al 2021] [Wu et al 2021] [Yang et al 2021] [de Paz 2021] [Almaya et al 2020] [Chapter 1 Perfume 2020] [Chen et al 2020, Multifunctional fabric coatings w] [Choi 2020] [Dobson 2020, ‘Drunk on the dead’ Intoxication] [Dobson 2020, Perfume, cigarettes and gilded bo] [Givaudan acquires fragrance ingredients 2020] [Givaudan develops new biotech 2020] [Jagadev and Beura 2020] [Laue et al 2020] [Melody M. Bomgardner 2020] [Nithya and Sasikala 2020] [Panchal and Mundkur 2020] [Road Perfume 2020] [Truan et al 2020] [White and du Vivier 2020] [Ammayappan et al 2019] [Bible References to Perfume 2019] [Corpus Alienum Cover the 2019] [Fragrance ingredients market poised 2019] [GIRL in Perfume 2019] [Gaby and Dalton 2019] [Identifying Perfume Ingredients in 2019] [Lin et al 2019] [Marag 2019] [Marc Reisch 2019] [Park et al 2019] [Perfume Ingredients in Nature 2019] [Perfume at Bethany 2019] [Phinta 2019] [Saptari et al 2019] [Sell 2019] [Sources of Perfume Ingredients 2019] [The Ingredients of Biblical 2019] [Udovichenko 2019] [Unilever offers fragrance ingredients 2019] [Wong et al 2019] [Ye et al 2019, All-Aqueous Direct Deposition of] [Zhan et al 2019] [Allen et al 2018] [Chisom Chinyerenwa et al 2018] [Cummings 2018] [De Bortoli 2018] [Dixon 2018] [Fragrance/scent 2018] [Libros COMO Perfume 2018] [PandG to divulge fragrance 2018] [Schuttelaar et al 2018] [Vanden Eynden et al 2018] [Froger 2017] [Global fragrance ingredients market 2017] [Lin and Emberger 2017] [Marc Reisch 2017] [Melody Bomgardner 2017] [Natsch et al 2017] [Notar Francesco et al 2017] [Studer 2017] [Zarogianni et al 2017] [Zhang et al 2017] [Comet perfume smells like 2016] [Costa and Mondello 2016] [Cousin 2016] [Guillemin 2016, § 2 Perfume Through the Ages] [Guillemin 2016, § 4 The Two Aspects of Perfume] [Guillemin 2016, § 7 From Fragrance Imitation to F] [Herman 2016] [Higashi 2016] [Pontén et al 2016] [Sobotková et al 2016] [Aamir 2015] [Allen et al 2015] [Biswas et al 2015] [Nijkamp et al 2015] [Tanaka 2015] [Alex Scott 2014] [Antoniotti 2014] [Fragrance ingredients market worth 2014] [IFF acquires Aromor to 2014] [Kneidel 2014] [Krueger 2014] [Mackey 2014] [Manufacture of Fragrance Ingredients 2014] [Substance Overview for Fragrance 2014] [The Design of New 2014] [smell, fragrance, perfume, rank 2014] [Bhatia et al 2013] [Davis 2013] [De-Luxe Extracts and Handkerchief 2013] [Khajavi et al 2013] [Kim 2013] [Kusumoputro and Na 2013] [Leszczyńska 2013] [Nishihara et al 2013] [Solubility Table of Principal 2013] [Teixeira et al 2013, Design of Perfumes] [Tobolkina et al 2013] [USE of Artificial Perfumes 2013] [Various Types of Perfumes 2013] [Veramendi et al 2013] [Bruze et al 2012] [Guéguen 2012, The Sweet Smell of … Implicit H] [Guéguen 2012, The sweet smell of… courtship E] [Havlíček and Roberts 2012] [Zhang and Cai 2012] [Briot 2011] [Dupau 2011] [Guéguen 2011] [Jung 2011, An Ethnography of Fragrance] [Marie Api and Vey 2011] [Masuck et al 2011, Inhalation exposure of children t] [Steinemann et al 2011, Chemical emissions from residenti] [Susami et al 2011] [Weifang 2011] [Al-Zadjali 2010] [Api and Vey 2010] [Chakraborty 2009] [Christensson et al 2009] [Rothlisberger 2009] [Goodner 2008] [Luan et al 2008] [Normand et al 2008] [Buckley 2007] [Chisvert and Salvador 2007] [Fixing Agent, Perfume 2007] [Harth et al 2007] [Lieu 2007] [Chen et al 2006] [Churchill 2006] [Everts 2006] [Jenner 2006] [Pybus 2006, Buying fragrance ingredients and] [Schubert 2006] [Shoji 2006] [Tomlinson 2006] [Yoh 2005] [Basketter et al 2004] [Treister 2004] [Özel and Clifford 2004] [Opiekun et al 2003] [Puig 2003] [Bridges 2002] [CHAPTER ONE. Shakespeare’s Perfume 2002] [Radha et al 2002] [Roberts and Vey 2002] [Roberts et al 2002] [Api 2001] [Balk et al 2001] [Jansson and Lodén 2001] [Rossiter 2001] [Scheinman 2001] [Broughan 2000] [Graham 2000] [Donkin 1999] [Ford et al 1999] [Gelled Fragrance 1999] [Pybus et al 1999, Measurement of fragrance percepti] [Pybus et al 1999, The search for new fragrance ingr] [Firmin et al 1998] [Fragrance Gelled Fragrance 1998] [Gelled Fragrance 1998] [Harder 1998] [Hotchkiss 1998] [Larsen 1998, A study of new fragrance mixtures] [Bain 1997] [Friberg 1997] [Jellinek 1997, Fragrance in cosmetic products] [Jellinek 1997, Men and fragrance] [Jellinek 1997, Odor Effects Diagram and personal] [Jellinek 1997, Personal perfume selection] [Jellinek 1997, The erotic effect of perfumes] [Jellinek 1997, The modern perfume] [Jitterbug Perfume 1984 1997] [Behan et al 1996] [Cao et al 1996] [Ledbetter 1996] [Bioprocess Production of Flavor 1995] [Buchbauer and Jirovetz 1994] [Maxwell 1994] [Ohloff 1994, Scent and Fragrances] [Graham 1993] [Nakamoto et al 1993] [Groom 1992] [Health hazard evaluation report 1992] [Meyer 1992] [Larsen 1990] [Mattingly 1990] [Weibel and Hansen 1989, Interaction of cinnamaldehyde a s] [Weibel and Hansen 1989, Penetration of the fragrance comp] [Byrne-Quinn 1988] [King 1988] [Le Norcy 1988] [Mensing and Beck 1988] [The international fragrance association 1987] [Bruze 1986] [Hsia et al 1986] [Jimbo 1983] [Wisneski et al 1983] [Bedoukian 1982] [Demole 1982] [Fragrance and Flavour Substances 1982] [Ohloff 1982] [The Perfume 1981] [Schissler 1980] [Beck and Beck 1978] [Collins and Mitchell 1975] [Opdyke 1975] [Aphrodisiac Perfume 1971] [The non-spill perfume and 1967] [Skeat 1966, A Fragment on the Ptolemaic Perfume Monopoly] [Skeat 1966, A Fragment on the Ptolemaic Perfume Monopoly P. Lond. Inv. 2859A] [Wright 1964] [Arctander 1963] [Cruickshank 1954] [The Greeks HAD Perfume 1946] [Breithut and Apfelbaum 1925] [Perfume Agencies in Canada 1925] [A Perfume Diffuser 1916] [Coal Tar Perfume 1863] [Making Perfume 1859] [Herrick 1648] [Aliyev] [Bolster] [Costa] [Firmado] [Fransson and Johnsen] [Garcia Leal] [Martins da Rocha] [Nakamoto et al]

Findings

The hypothesis adjudicated

H1, dose, is partially supported. Its second clause holds without exception. The fourth spray adds less than the third, by $\sqrt{4/3}$ in detection radius and by about fifteen percent in perceived intensity at a fixed distance, and this follows from the square-root scaling of the plume and the compressive power law of perception, neither of which depends on the calibrated threshold. Its first clause, that three or four sprays is the smallest adequate dose, is rejected in four of the six scenarios and supported only in modified form in the remaining two. For dinner and the interview the adequate dose is one. For the shared office and the elevator no positive dose is adequate. For the open-plan office, four sprays are adequate only when split into a morning application and a midday sequel. Outdoors, four sprays are adequate only for an extrait, and an eau de parfum needs six.

H2, placement, is partially supported. The conventional points are broadly sound and the conventional reason for them is not. No pulse-specific mechanism was found. Warmth operates, through vapour pressure, and is worth about one spray in four. The dominant mechanisms are geometric, namely distance to the receiver, the thermal plume that carries torso emissions upward, and distance to the wearer’s own nose. The neck, chest and nape survive on geometry, and the wrist fails on temperature, attrition and self-exposure together.

H3, the wearer, is supported. Every conventional difference between men’s and women’s points with a physical basis resolves to clothing or hair, and the receiver’s sex has an effect smaller than the pump can resolve. Wearers do differ in how fast their skin releases a fragrance, and the literature attaches that difference to skin properties rather than to sex.

The overall hypothesis is partially supported.

Doctrine

The findings reduce to a short set of rules, each traceable to a section above.

  1. State the end state before choosing a count. A spray count without a receiver, a distance, a room and a duration is not a plan.
  2. Convert to spray-equivalents. Four sprays of eau de toilette and four of extrait differ by a factor of two and a half.
  3. Check the room before the wearer. If the room’s volume times its air change rate is small, the room becomes the source and no count separates intended from unintended receivers.
  4. Default to one spray at the sternum. It meets the close-range end states, which are where most fragrance is worn.
  5. Split rather than escalate. For a long day, a morning application and a midday sequel outperform a single larger application with fewer sprays.
  6. Never reapply on the wearer’s own judgement. Schedule the sequel in advance or ask a red cell.
  7. Prefer the trunk, the nape, the hair and the garment to the wrists.
  8. When the sign of the objective is unknown, apply zero.
  9. Do not apply human fragrance to animals, and treat every room product as an application to every occupant of the room.

Epistemic State

Measured and sourced. The physical constants and product facts are sourced. These are the pump volumes from a manufacturer’s specification, the enthalpy of vaporisation of linalool, the flash point of ethanol, the concentration ranges of the product classes, the ventilation rates from the Environmental Protection Agency, the thermal plume velocity, the odour power-law exponents, the age, sex and specific anosmia findings, the allergy prevalence and the regulatory limits. Each is cited to a source that was read in full or in abstract. The Craven and Settles plume velocity, the dates of the DeVilbiss perfume atomizer, the Chanel application advice, the Metropolitan Museum and VCA pages, and several retail claims were confirmed only from search results and not from the pages themselves, and they are worded accordingly.

Primary sources and how each was read. Where a secondary source carried a claim and a primary one could be retrieved, the primary was added. Read in full or in the relevant passage are Rimmel’s Book of Perfumes, for the eau de Cologne and kyphi passages, Plutarch’s account of kyphi, the DeVilbiss patent record, the registered bear spray label, and the Access Board’s recommendations. Read in abstract are Dalton and Wysocki on long-term adaptation, Zaynoun on bergamot phototoxicity, Api on QRA2, Kimber on dose per unit area, and Doty on age, each of those four being the first author of a paper with several. Three are cited for no more than their titles state, because only their bibliographic records could be retrieved. These are Clapeyron in translation and Clausius, for the origin of the vapour-pressure relation, and Whissell-Buechy and Amoore, for the report of musk odour-blindness as a simple recessive trait. No retrievable primary was found for the Gaussian plume, whose standard workbook could not be obtained, for Tapputi, whose tablet is known here through an encyclopedic summary, or for the text of the 2009 CDC policy.

Surveyed. The survey’s 2,541 works were admitted by title, so its rows establish what has been published under a heading and not what each work found. The 59 works its prose discusses were read in abstract, five of them could be named only for their titles, and the four excluded literatures named in its method are excluded by design. Its year statistics are computed from bibliographic records, which can carry the year of an online version in place of the print year.

Modelled. Every number in the adjudication tables is the output of a deterministic model whose equations are all displayed in the article and whose parameters are all listed in the planning assumptions. The model is deliberately simple. It collapses a fragrance into one pool with one time constant, treats the plume as a Gaussian with linear spreading in steady air, treats each room as perfectly mixed, and represents receivers by a log-normal threshold. Each of these is wrong in detail, and the sensitivity analysis is the article’s account of how much that matters. The structural results, namely the square-root scaling, the dose-independence of the radius half-life, the infeasibility of the small shared office, the elevator’s standing cost, and the advantage of the split sequel over escalation, follow from the form of the equations and survive every variation tested. The calibrated results, namely the specific counts for the open-plan office and the outdoor event, do not survive every variation and are illustrations.

Assumed. The deposition efficiency of 0.70, the time constant of three hours, the adaptation floor and time constant, the handwashing removal fraction and interval, the overkill threshold at thirty times the detection threshold, the reed diffuser emission rate, the atomizer’s spray half-angle of 20 degrees, the linalool fraction of a tenth used to defend the calibrated threshold, and the eight colleagues in the collateral headcount are planning values with no direct source. The adaptation values are bracketed by the experiments the survey found, with significant losses at five and ten minutes, but they are not measured values for a fragrance worn on the body.

Not found. No peer-reviewed study was found of a pulse-specific mechanism, of skin hydration or oiliness as a determinant of fragrance longevity, of the effect of rubbing an application, of optimal spray distance, or of fragrance retention on worn clothing. The conventional advice on all of these rests on retail and editorial sources, and the article reports it as convention rather than as evidence. The conventional plans in the placement tables are a composite of commonly repeated advice rather than a quotation of any single source, because most of the editorial sources could not be retrieved in full.

One revision after adjudication. The first run of the adjudication required detection with probability 0.8, averaged over the scenario window, and found almost every scenario infeasible, because an exponentially decaying source cannot hold a high detection probability for eight hours without overkill at the start. The threshold was lowered to 0.5, more likely than not, before any spray count result was examined, and this is the exception noted in the statement of the hypothesis. The infeasibility at 0.8 is itself a finding, and it is the reason the sequel exists.

Vantage. The article carries an editorial date of 5 October 2025 and was written a year later. A small number of sources postdate the editorial date, most visibly the International Fragrance Association’s letter of August 2026 on its 52nd amendment, and they are cited because they are the current statement of a standard rather than because the analysis depends on them.

Where to disagree. A reader with measured emission curves for a real fragrance on real skin should replace the lumped time constant and rerun the tables. A reader with a measured detection threshold for a blend should replace the calibrated value, which would move the open-plan and outdoor counts and nothing structural. A reader who believes the collateral constraint is too strict is disputing the end state, not the analysis, and the analysis supports that dispute being had explicitly.

Out of Scope

  • Fragrance composition and selection. Which fragrance to wear is a separate question. The finding of Lenochová and colleagues that people choose perfumes that blend well with their own body odour suggests that the wearer’s own choice carries information this article does not model.
  • Pheromone claims. Products marketed as containing human pheromones are outside the analysis, since Wyatt’s review found no robust bioassay-led evidence that any proposed human pheromone is one.
  • Cultural practice. Traditions of fragrance use that differ from the Western spray convention, including attar and bakhoor, are mentioned and not analysed.
  • Health effects beyond irritation and sensitisation. Questions about endocrine activity of fragrance constituents are outside the evidence reviewed.
  • Scent marketing. The deliberate scenting of shops and hotels is a room application by a commercial actor and is not assessed.
  • Offensive applications. Pepper spray, bear spray and malodorants are bounded in their own section and are not analysed.
  • Literatures excluded from the survey. Smell loss after coronavirus infection, environmental odour nuisance, electronic noses and food flavour are excluded from the survey by design. Each is large, and each bears on a receiver or an instrument and not on an application.
  • Storage and degradation. Fragrance degrades with heat and light, and the effect on the emission model of a degraded product is not modelled.

Conclusion

The question asked for the conventional application points under the three-push and four-push scenarios, and the conventional answer exists. For men it is both sides of the neck and the chest, with the nape or the wrists as the fourth. For women it is the wrists, the neck, behind the ears and the décolletage, with the hair as an option.

The adjudicated answer differs from it in three ways. The points move toward the sternum, the nape, the hair and the garment, and away from the wrists, because the operative mechanisms are geometry and attrition rather than the pulse. The counts fall, because the encounters in which fragrance is mostly worn are close, indoor and short, and one spray of eau de parfum meets them. And the four-push survives only as a plan executed in two phases, three sprays in the morning and one at midday, which outperforms a single application of five.

The hypothesis that the conventional doctrines are sound is partially supported. They name defensible points for the wrong reason and prescribe a dose calibrated to no stated end state. The single most consequential finding is not about points or counts at all. It is that the wearer, who decides when the fragrance has faded, is the one receiver whose perception has been degraded by the application itself, and that every plan which leaves reapplication to the wearer’s judgement ends in overapplication. The remedy is a schedule or a second opinion, and the second opinion is free.

The contemporary literature, surveyed here across 2,541 works, supports that finding more directly than the article expected, with experiments showing adaptation within minutes and a perfume degrading its own wearer’s sense of smell. It does not answer the question the article began with. No study located measures detection by other people as a function of spray count, compares application points on the body, or tests the conventional advice on distance, rubbing or moisturising. The conventional answers to the original question are therefore not contradicted by the literature. They are untouched by it.

References