Every fact on this site, with its evidence grade, its caveats and a link to the source.
We start you on the strong ones: findings that have been replicated or come from one large, well-controlled study. Moderate and weak facts are here too, labeled for what they are. Use “Link to this fact” to share a single card.
What you can do / Review of other studies
Never mix bleach with ammonia or acidic cleaners: 13 published poisoning reports, including one death, came from mixing products.
Strong evidence: Case reports; not fragrance-related.
Source: Nazaroff & Weschler 2004, Atmospheric Environment Link to this fact
What you can do / Review of other studies
Choosing fragrance-free personal care products is a reasonable way to cut DEP exposure, since DEP is used as a fragrance solvent; label reading alone will not catch phthalates.
Strong evidence: Reasoned advice; not tested as an intervention in this paper.
Source: Crinnion 2010, Alternative Medicine Review Link to this fact
What you can do / Measured in people or real products
If you have unexplained or recurring dermatitis, ask whether patch testing will include oxidized linalool (and oxidized limonene); standard fragrance tests missed 60% of these allergies.
Strong evidence: Hydroperoxide tests now recommended for baseline series in Europe.
Source: Christensson 2012, Contact Dermatitis Link to this fact
What you can do / Review of other studies
Never mix bleach with ammonia or acidic cleaners: it makes toxic chloramine or chlorine gas.
Strong evidence: Established chemistry; review restates it.
Source: Salonen 2024, Environment International Link to this fact
What you can do / Measured in people or real products
Choosing fragrance-free cosmetic and personal care products is an effective way to cut DEP exposure, since fragrance is consistently the most DEP-dense product category across three independent national surveys and DEP is never named on a label when present via fragrance.
Strong evidence: Based on product-content measurement across three independent surveys (Hubinger & Havery 2006, Dodson 2012, Koniecki 2011), not a tested behavioral intervention.
Source: Koniecki 2011, Environmental Research Link to this fact
What you can do / Self-reported survey
About twice as many Australians would prefer fragrance-free workplaces (42.8%) as fragranced ones (22.2%), and over three times as many prefer unscented flights (57.7% vs 16.3%).
Moderate evidence.
Source: Steinemann 2017, Preventive Medicine Reports Link to this fact
What you can do / Self-reported survey
Most people would rather have fragrance-free spaces: 65% prefer fragrance-free airplanes, 61% hotels, 51% health care and 48% workplaces, against 16-22% who prefer them fragranced.
Moderate evidence: Preference survey, adults 18-65.
Source: Steinemann 2019, Air Quality, Atmosphere & Health Link to this fact
What you can do / Self-reported survey
People with asthma back fragrance-free spaces by wide margins: 66.2% vs 16.1% for fragrance-free workplaces and 72.1% vs 14.8% for fragrance-free health care.
Moderate evidence.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
What you can do / Measured in people or real products
Screening out products whose labels list 'fragrance' and a few other terms cut synthetic fragrance: 26 of 43 screened products had no detectable fragrance chemical, and high fragrance levels appeared 21 times in conventional samples vs 2 in screened ones.
Moderate evidence: Conventional composites vs single alternatives not directly comparable; did not remove parabens, phthalate substitutes.
Source: Dodson 2012, Environmental Health Perspectives Link to this fact
What you can do / Self-reported survey
Swedes overwhelmingly prefer scent-free spaces: 80.2% vs 6.0% for airplanes, 77.7% vs 9.8% for hotels, and 64.1% vs 14.0% for health care.
Moderate evidence.
Source: Steinemann 2018 (Sweden), Air Quality, Atmosphere & Health Link to this fact
What you can do / Measured in people or real products
Perfume was the strongest single predictor of diethyl phthalate exposure, so skipping perfume and fragranced personal care products is the most obvious way to lower it.
Moderate evidence: Association only; not tested as an intervention.
Source: Parlett 2013, Journal of Exposure Science and Environmental Epidemiology Link to this fact
What you can do / Measured in people or real products
Green, organic or natural labels on baby products did not mean fewer released chemicals, so choosing products labeled fragrance-free (without essential oils) is the more reliable way to avoid scent chemicals.
Moderate evidence.
Caveats
Fragrance-free products were not tested directly for VOC emissions (Nematollahi 2018's own scope). Hamann 2015 shows a different but relevant caution: even 'fragrance-free' US pediatric products commonly contain non-fragrance contact allergens (80.8% of 52 had >=1 NACDG-tray allergen, mostly preservatives), so 'fragrance-free' is more reliable specifically against added-scent VOCs, not against contact allergens generally.
Source: Nematollahi 2018, Air Quality, Atmosphere & Health Link to this fact
What you can do / Measured in people or real products
Researchers recommend lower-terpene (less citrus/pine-scented) cleaners, diluting them, ventilating during and for hours after cleaning, cleaning when fewer people are home, and never running ozone generators or ionizers with these products.
Moderate evidence: Author recommendations derived from chamber chemistry, not tested as interventions.
Source: Singer 2006, Atmospheric Environment Link to this fact
What you can do / Self-reported survey
More UK adults prefer fragrance-free over fragranced workplaces (44.7% vs 23.3%), health care (43.3% vs 26.7%) and airplanes (61.9% vs 18.4%).
Moderate evidence: Pluralities, not majorities, for workplace and health care; preference, not health benefit.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
What you can do / Review of other studies
People with suspected fragrance dermatitis should ask for patch testing that includes oxidized limonene and linalool, because standard fragrance screens miss many cases.
Moderate evidence.
Source: Sukakul 2024, Acta Dermato-Venereologica Industry-funded Link to this fact
What you can do / Measured in people or real products
Taking the air freshener out of the car removes its main added chemical: without one, in-car limonene was about 5-6 ug/m3.
Moderate evidence: Small pilot; limonene only.
What you can do / Measured in people or real products
People with unexplained dermatitis can ask for patch testing with oxidized limonene and linalool; standard screens can miss these allergies.
Moderate evidence.
Source: Bråred Christensson 2016, Contact Dermatitis Industry-funded Link to this fact
What you can do / Measured in people or real products
Using fewer scented personal care products is likely to lower phthalate and paraben levels, because levels tracked the number of products used.
Moderate evidence: Association; not tested as an intervention here (see HERMOSA).
Source: Braun 2014, Journal of Exposure Science and Environmental Epidemiology Link to this fact
What you can do / Measured in people or real products
When 100 teenage girls swapped their usual personal care products for ones labeled free of phthalates, parabens, triclosan and oxybenzone for just 3 days, levels of these chemicals in their urine fell by 27-45%.
Moderate evidence: No control arm, 100 Latina girls in one town, 3 days, summer.
Source: Harley 2016, Environmental Health Perspectives Link to this fact
What you can do / Measured in people or real products
The phthalate most linked to fragrance (diethyl phthalate) fell by 27% in 3 days when girls avoided products listing fragrance unless labeled phthalate-free.
Moderate evidence: Multi-product swap; fragrance effect not isolated; other DEP sources remain.
Source: Harley 2016, Environmental Health Perspectives Link to this fact
What you can do / Journalism
Treat vague words like 'natural', 'green', 'eco-friendly' or 'for sensitive skin' as marketing, not evidence: read the ingredient list for parfum/aroma, essential oils and named fragrance allergens. Even 'fragrance-free' can allow essential oils and multifunctional allergens such as benzyl alcohol.
Moderate evidence.
Caveats
The 'vague claims are unreliable' half rests on several independent primaries (Steinemann 2011, Nematollahi 2018, Dodson 2012, Klaschka 2016) and remains well supported. But the claim's own recommended action, 'read the ingredient list', is now shown by Noiesen 2007 (382 patch-test-confirmed allergic patients, 3 Danish clinics) to be difficult or extremely difficult for 46% of allergic patients overall, significantly worse for lower educational level (OR 1.85) and for formaldehyde/MDBGN allergy specifically (OR ~2 each). Per our grading rule, a claim with an unverified or now-shown-difficult part stays below strong.
Source: Dahl 2010, Environmental Health Perspectives Link to this fact
What you can do / Measured in people or real products
EPA's TEAM investigator recommended source control at home: stop using air fresheners and moth crystals, and air out dry-cleaned clothes.
Moderate evidence: Recommendation derived from source apportionment, not a tested intervention.
Source: Wallace 1991, Environmental Health Perspectives Link to this fact
What you can do / Measured in people or real products
Choose unscented feminine hygiene products rather than relying on organic or natural labels, and avoid frequent vaginal douching and feminine powder use: scented tampons had far more terpenes in product testing, and a separate NHANES biomarker study found frequent douching (2+ times/month) linked to 81% higher blood 1,4-dichlorobenzene (dose-response, p=0.04) and feminine powder use linked to 36% higher blood ethylbenzene.
Moderate evidence.
Caveats
The scented-tampon comparison rests on only 2 scented vs 20 unscented tampons (weak on its own); the douching/powder biomarker evidence is stronger (real blood measurements, dose-response for douching) but cross-sectional and self-reported, with mothballs/toilet deodorizers as an unruled-out alternate DCB source. The same biomarker study (Ding 2020) found NO significant blood-VOC association with tampon or pad use itself.
Source: Lin 2020, Environment International Link to this fact
What you can do / Review of other studies
If you have unexplained eczema, ask for patch testing that includes oxidized limonene and linalool, now recommended for the European baseline series.
Moderate evidence.
What you can do / Measured in people or real products
Don't run ozone-generating air purifiers while using scented cleaners: the particle burst from a limonene cleaner only happened when ozone was present, including from a commercial ozone-generating purifier.
Moderate evidence: One product; ozone-free run had no particle-number increase.
Source: Rossignol 2013, Atmospheric Environment Link to this fact
What you can do / Measured in people or real products
If you have eczema, ask for patch testing that includes oxidized linalool and limonene: they are not in every standard test series, so the allergy can be missed.
Moderate evidence: The authors say more clinical-relevance data are needed before routine screening.
What you can do / Review of other studies
If you are allergic to fragrance, check the full ingredient list of "fragrance-free" products and prescribed creams for benzyl alcohol, and ask for patch testing with your own products if reactions continue.
Moderate evidence.
Caveats
Practical clinical advice. Xu 2017 shows why the full list matters (45% of 'fragrance-free' US moisturizers had a fragrance cross-reactor or botanical), but Rodriguez 2024 notes several hundred label names signal fragrance, so a checked database may be more reliable than label reading. Noiesen 2007 (382 patch-test-confirmed allergic patients) now quantifies the difficulty of this specific action: 46% found reading ingredient labels difficult or extremely difficult overall, education-graded. It does not test benzyl alcohol allergy specifically or outcomes, so the grade is unchanged at moderate.
What you can do / Review of other studies
Occupational lung specialists treating irritable larynx syndrome recommend a 'low-scent' workplace policy or respiratory protection to limit exposure to triggers.
Moderate evidence: Clinical recommendation, not tested as an intervention.
What you can do / Review of other studies
Fragrance-free cosmetics and laundry products cut the main routes by which synthetic musks enter the body: skin contact and washed clothing.
Moderate evidence.
Caveats
Route inferred from exposure data; no intervention study of musk body burden. Hutter 2009 (100 Vienna adults) gives cross-sectional human support for the polycyclic musks specifically: monthly-frequency of body lotion and perfume use significantly predicted blood galaxolide/tonalide (beta=0.188-0.192, p<0.05); no cosmetics-use variable predicted nitro-musk (musk ketone/musk xylene) blood levels there. Lignell 2008 (101 Swedish mothers, milk 1996-2003) gives a second, milk-matched confirmation with per-product specificity: perfume use predicted HHCB and perfumed-laundry-detergent use predicted AHTN, but musk xylene showed no association with any product category tested. Still no before/after intervention trial for any musk, and the nitro-musk part of the action's benefit remains unverified in two independent studies now.
Source: Schmeiser 2001, International Journal of Hygiene and Environmental Health Link to this fact
What you can do / Measured in people or real products
Musk levels in blood and milk seem to track current personal-care product use rather than lifetime storage: Hutter 2009 found that how often people used perfume and body lotion significantly predicted their blood levels of the polycyclic musks (galaxolide, tonalide) in 100 adults, so choosing fragrance-free personal care and laundry products during pregnancy and breastfeeding is a plausible way to lower a mother's musk levels and, in turn, transfer to the baby.
Moderate evidence.
Caveats
Route inferred in Reiner 2007 from the absence of an age trend in milk, and now supported by direct product-use data in two independent populations and matrices: Hutter 2009 (blood, non-pregnant Vienna adults) and Lignell 2008 (101 Swedish mothers, milk itself — the exact matrix this claim concerns). Lignell 2008 found perfume-use frequency predicted HHCB and perfumed-laundry-detergent use predicted AHTN in milk, but no product-use variable predicted musk xylene, matching Hutter's blood-based polycyclic/nitro split. Still correlational and cross-sectional; no study has measured milk musk levels before and after a change in a mother's product use, and no cosmetics-use variable has ever predicted a nitro musk in either study.
Source: Reiner 2007, Environmental Science & Technology Link to this fact
What you can do / Review of other studies
If you have fragrance allergy, look for benzyl salicylate on the ingredient list (and hexyl salicylate, which cross-reacted with it in human tests); EU rules require named fragrance allergens to be declared above threshold.
Moderate evidence: Cross-reaction evidence: subjects induced with 30% hexyl salicylate reacted to 15% benzyl salicylate, in an industry report.
Source: RIFM Expert Panel / Belsito 2007, Food and Chemical Toxicology Industry-funded Link to this fact
What you can do / Animal study
Methyl salicylate (wintergreen oil) is a strong eye irritant in animal tests, causing irritation even at about 1%, and is toxic if swallowed; keep wintergreen oils and rubs away from children's eyes and mouths.
Moderate evidence: Rabbit eye tests (neat and 1.25% in alcohol); oral toxicity from acute rodent data and the well-known methyl salicylate poisoning literature outside this paper.
Source: RIFM Expert Panel / Belsito 2007, Food and Chemical Toxicology Industry-funded Link to this fact
What you can do / Measured in people or real products
The California Department of Public Health recommends enforced fragrance-free workplace policies, no air fresheners or fragranced cleaners, and better ventilation instead of odor masking.
Moderate evidence: Recommendation from a public-health agency based on surveillance, not an intervention trial.
What you can do / Review of other studies
Even the toxicologists who set these limits suggest stricter, setting-specific limits where people breathe through the mouth during exercise, such as sports halls, playgrounds and schoolyards.
Moderate evidence: A proposal, not a finding; no values are given.
Source: Kleinbeck & Wolkoff 2024, Archives of Toxicology Industry-funded Link to this fact
What you can do / Self-reported survey
A fragrance-free sign is not enough on its own: Canadians with chemical sensitivities described workplaces and hospitals with 'scent-free' policies where staff still wore scents and scented cleaners stayed in use.
Moderate evidence: Qualitative focus groups, n=60 self-selected MCS/IAQ-affected Canadians; advocacy-funded.
Source: Roy 2026 Link to this fact
What you can do / Self-reported survey
Fragrance-free policies need to cover cleaning and laundry products, not just perfume: of 60 people who react to fragranced products, 50 named cleaning products, 47 perfume and 41 laundry products as persistent triggers.
Moderate evidence: Self-selected Canadian sample (90% female); counts of participants naming a source, not exposure measurements.
Source: Roy 2026 Link to this fact
What you can do / Review of other studies
Smell scientists reviewing the evidence found that scenting workplaces to boost mood or productivity is not well supported, and noted that a chemically intolerant employee can react to a fragranced workplace.
Moderate evidence: Short narrative review; the positive-scent literature it weighs is small; no primary data.
Source: Dalton & Jaén 2010, Current Opinion in Allergy and Clinical Immunology Industry-funded Link to this fact
What you can do / Measured in people or real products
If you get recurring rashes, ask for patch testing: nickel and fragrance are the most common findings in the general population, and one fragrance test alone misses many fragrance allergies.
Moderate evidence.
What you can do / Self-reported survey
Support for fragrance-free health care and workplaces is not limited to people with symptoms: in Germany roughly 70% of those who backed them reported no fragrance-related health effects themselves.
Moderate evidence: Our arithmetic from Table 5; preference, not outcome; German workplace support was only 33.2% (30.6% against, 35.3% unsure).
Source: Klaschka 2020, Environmental Sciences Europe Link to this fact
What you can do / Review of other studies
If you are allergic to fragrance, dermatologists advise avoiding all fragrance rather than only the chemicals you tested positive to, and choosing products from a checked database such as the ACDS CAMP list or SkinSAFE instead of trusting 'fragrance-free' claims.
Moderate evidence.
Caveats
Expert advice, untested against label reading; COI: authors built/lead CAMP. Noiesen 2007 (382 patch-test-confirmed allergic patients) now quantifies why the review distrusts label reading: 46% of allergic patients found reading ingredient labels difficult or extremely difficult, education-graded, still 38% among fragrance-only patients. This corroborates the rationale for recommending a database over labels but does not test whether database-guided avoidance actually outperforms label reading on outcomes, so the grade stays moderate.
What you can do / Review of other studies
For fragrance-allergic people, dermatologists recommend removing diffusers, scented candles, room deodorizers, incense and wax melts, switching household cleaners, wipes and laundry products to fragrance-free, and bringing your own shampoo to the salon and your own oil to massages.
Moderate evidence: Expert advice; the salon point rests on a single exposure keeping skin flared up to ~4 weeks (clinical observation).
What you can do / Measured in people or real products
If a child develops unexplained breast tissue, tell the doctor about every product put on the skin, including homemade balms and essential-oil or 'natural' products; in one reported case the lavender balm came to light only after repeated questioning.
Moderate evidence: Practical advice from a case report; not evidence the oil was the cause.
Source: Henley 2007, New England Journal of Medicine Link to this fact
What you can do / Government agency
EPA's own first advice on indoor VOCs is to identify and remove the source, ventilate when products are used, and buy only what you will use soon, because even closed containers leak.
Moderate evidence: Generic VOC advice; EPA does not single out fragrance.
Source: US EPA 2026 Link to this fact
What you can do / Measured in people or real products
Ventilation and less ozone help: in the same test room, with lower ozone (25–30 ppb) and nearly 3× the air exchange, particle mass from perfume, hair spray and body spray fell by more than half.
Moderate evidence: One supplementary run; ozone and ventilation changed together, so their separate effects are unknown.
Source: Wu 2024, Environmental Science & Technology Letters Link to this fact
What you can do / Review of other studies
Check ingredient lists of leave-on products such as makeup, powders and glitter, not just scrubs, for plastic ingredients; ingredient-scanning apps such as Beat the Microbead flag them.
Moderate evidence: App described by the review; completeness of the app's polymer list not assessed.
What you can do / Self-reported survey
Fragrance-free health-care policies should cover cleaning and laundry products, not just staff perfume; Canadian advocates ask for exactly this, and people who react name cleaning products as their most common trigger (50 of 60).
Moderate evidence: Advocacy position plus a self-selected focus-group sample; no evidence yet that policies reduce exposure or symptoms.
What you can do / Government agency
Workplace accommodations for fragrance sensitivity do not have to be a building-wide ban: the US Labor Department's Job Accommodation Network lists scent-free meeting rooms, moving a worker away from air fresheners and vents, telework, air purifiers, signage and staff education.
Moderate evidence: List of options, not tested for effectiveness.
What you can do / Review of other studies
Pediatric dermatologists advise that products for children be mild, slightly acidic and fragrance-free.
Moderate evidence: Expert recommendation citing reviews (Kuller 2016, Fernandes 2011); the survey itself linked no product to any skin outcome.
Source: Melo 2020, Revista Paulista de Pediatria Link to this fact
What you can do / Measured in people or real products
Allergen-free moisturizers were no more expensive than others: the cheapest best-sellers with no common skin allergen were plain petroleum jelly and single-ingredient butters and oils, from about $0.28 an ounce.
Moderate evidence: 2016 prices; 'allergen-free' means no NACDG-series ingredient listed; natural oils vary in efficacy (olive oil may harm the barrier).
What you can do / Measured in people or real products
If you have fragrance allergy or eczema, don't rely on "fragrance free", "hypoallergenic" or "dermatologist recommended": in best-selling US moisturizers these claims often coexisted with listed skin allergens, so check the full ingredient list or a dermatologist-checked product list.
Moderate evidence: Advice follows from a label survey; not tested against reaction outcomes; two authors hold equity in a product-recommendation service.
What you can do / Animal study
Treat essential oils as perishable: keep bottles closed and don't keep old, long-opened oils for skin use, because their scent chemicals oxidize into skin allergens in air.
Moderate evidence: Mechanism shown in lab (open flasks); real-bottle oxidation rates and the benefit of these habits not tested.
Source: Hagvall 2008, Contact Dermatitis Industry-funded Link to this fact
What you can do / Measured in people or real products
Choose unscented tampons, liners and pads, and read "fresh" on the pack as "fragranced": the allergens inside will not be listed.
Moderate evidence: Allergens shown in scented products only; unscented products were bought but not reported; no evidence that switching reduces dermatitis.
What you can do / Measured in people or real products
How much formaldehyde and particle pollution formed was set mainly by how much ozone was available, not by how much product was used, so running an ozone-generating air purifier or ionizer alongside scented cleaning products or air fresheners adds directly to indoor formaldehyde and particles.
Moderate evidence: Conclusion drawn from controlled chamber chemistry (ozone as the limiting reagent in every run), not tested as a real-world intervention.
Source: Destaillats 2006, Environmental Science & Technology Link to this fact
What you can do / Measured in people or real products
Take used paper towels, sponges and mop water out of the room right after cleaning, ventilate during and after, and choose cleaners without 2-butoxyethanol (ethylene glycol monobutyl ether / butyl cellosolve on the label or SDS); avoid running ozone generators with terpene-scented products.
Moderate evidence: Author recommendations derived from chamber chemistry, not tested as interventions.
Source: Singer 2006, Indoor Air, Indoor Air Link to this fact
What you can do / Measured in people or real products
Being below a standard occupational exposure limit does not mean an irritant gas is safe for someone with asthma: chamber studies found severe asthma attacks from sulfur dioxide and sulfuric acid at concentrations at or below typical workplace limits for those substances.
Moderate evidence: Occupational limits are set for healthy workers by design; this is not itself an argument that the limits are wrong, only that they don't protect people with asthma.
Source: Johansson 2016, Critical Reviews in Toxicology Link to this fact
What you can do / Measured in people or real products
If you are diagnosed with oxidized-linalool contact allergy, avoiding products listing linalool or fragrance/parfum is worth doing even at low concentrations, since repeated use at product-realistic doses reproduced dermatitis in a clinical trial, and most participants who had already stopped using linalool-containing products reported their dermatitis improved.
Moderate evidence: Self-reported improvement on avoidance (4 of 5) is not blinded or controlled; the ROAT elicitation data (the stronger evidence) show reactions down to 0.3% oxidized linalool.
Source: Andersch Björkman 2014, Contact Dermatitis Link to this fact
What you can do / Measured in people or real products
Avoid frequent vaginal douching and feminine powder use as a modifiable source of blood VOC exposure, on top of existing medical advice against douching for infection risk.
Moderate evidence: Biomarker association from cross-sectional self-report data, not an intervention trial.
Source: Ding 2020, Journal of Women's Health Link to this fact
What you can do / Measured in people or real products
How often someone used body lotion and perfume was directly linked to how much of the synthetic musks galaxolide and tonalide were in their blood, giving direct human evidence that switching to musk-free lotions and perfumes could lower blood levels of these fragrance chemicals.
Moderate evidence: Cross-sectional frequency-of-use questionnaire, not an intervention; the link was not shown for musk ketone or musk xylene, only for the polycyclic musks.
Source: Hutter 2009, Science of the Total Environment Link to this fact
What you can do / Measured in people or real products
If you have a confirmed (not just borderline) positive patch test to limonene hydroperoxides, avoiding products with appreciable oxidized/aged limonene is well supported: realistic product-level doses reliably triggered a reaction in this group.
Moderate evidence: Applies to confirmed reactors; a borderline patch-test result is much weaker evidence of true allergy.
What you can do / Measured in people or real products
If you have known fragrance allergy, ask your pharmacist or read the full leaflet (not just the outer box) for topical medicines, and request fragrance-free formulations for wound care, NSAID gels and antiseptics where alternatives exist; if a topical medicine causes a rash, ask for patch testing with the actual product and its individual ingredients, not just the standard fragrance mix.
Moderate evidence: Practical advice drawn from a single clinic's experience; a negative fragrance-mix patch test does not rule out fragrance allergy from a specific product.
What you can do / Measured in people or real products
In a study of 25 UK homes, easy-to-check building factors (home age, size, number of occupants, single- vs double-glazing) showed no measurable relationship to indoor scent-chemical levels; the homes with the highest levels were those whose occupants reported heavy cleaning/fragrance-product use.
Moderate evidence.
Caveats
Glazing comparison used t-tests on 19 homes with no ventilation-rate data; product-use link is a qualitative activity-log correlation, not a controlled experiment A larger same-lab study (Heeley-Hill 2021, 60 UK homes, daily diaries; Givaudan-funded fieldwork) found cumulative product-use frequency had almost no predictive power for measured VOC levels (R²<0.001), so treat the product-use link as suggestive.
Source: Wang 2017, Environmental Science: Processes & Impacts Link to this fact
What you can do / Self-reported survey
During pregnancy, prefer pouring or wiping cleaning products rather than spraying them, and limit solvent and air-freshener use, since spray application was the exposure most consistently linked to infant respiratory symptoms across this and sibling cohort studies.
Moderate evidence.
Caveats
Based on an observational association, not a controlled trial; the authors' own explanation (spraying increases inhaled dose of both volatile and non-volatile components) is plausible but unproven.
Source: Casas 2013, International Journal of Public Health Industry-funded Link to this fact
What you can do / Self-reported survey
More than a third of people surveyed (37%) report avoiding at least one leave-on scented product (perfume, deodorant, skin cream) because it has caused them skin problems.
Moderate evidence.
Caveats
Self-reported avoidance, not a clinical diagnosis; nearly identical rates in the full interviewed sample (12,377) and the smaller patch-tested subsample (3,119), supporting representativeness.
Source: Diepgen 2015 (EDEN), British Journal of Dermatology Industry-funded Link to this fact
What you can do / Measured in people or real products
People with chronic, treatment-resistant hand eczema and a history of reacting to scented products can ask their dermatologist for patch testing beyond the standard fragrance mix, including citral, Lyral, hydroxycitronellal and oxidized limonene/linalool.
Moderate evidence: Based on one clinical population's reaction pattern (Heydorn 2003); a dermatologist should tailor markers to local product exposure.
Source: Heydorn 2003, Contact Dermatitis Industry-funded Link to this fact
What you can do / Measured in people or real products
Because galaxolide (HHCB) levels in milk tracked perfume use and tonalide (AHTN) levels tracked scented-laundry-detergent use specifically, choosing fragrance-free perfume and fragrance-free laundry detergent during pregnancy and breastfeeding are each independently plausible ways to lower the corresponding musk chemical passed to a nursing infant.
Moderate evidence.
Caveats
Correlational and cross-sectional, no before/after intervention trial; musk xylene (a nitro musk) showed no association with any product category tested, so this action would not address that compound.
Source: Lignell 2008, Environmental Science & Technology Link to this fact
What you can do / Measured in people or real products
For parents of infants, diaper cream is an under-recognized DEP source that deserves attention alongside fragranced products, not instead of them.
Moderate evidence: Based on a Canadian exposure model with non-Canada-specific use-pattern inputs, not measured infant biomarkers.
Source: Koniecki 2011, Environmental Research Link to this fact
What you can do / Measured in people or real products
A direct chemical test of real fragrance products found no build-up of the allergenic breakdown product (linalool hydroperoxide) even after 9 months of worst-case accelerated aging, so for fine fragrances and antiperspirants specifically, letting a bottle sit open for months to years did not measurably increase this particular hazard.
Moderate evidence.
Caveats
Covers only fine fragrance and antiperspirant formulations tested by one industry lab; does not cover creams, lotions or other product categories, and does not test whether the general advice to discard old products reduces dermatitis.
Source: Kern 2014, Analytical and Bioanalytical Chemistry Industry-funded Link to this fact
What you can do / Measured in people or real products
Clinicians managing irritable larynx syndrome most often treat reflux (medication and lifestyle measures) and provide voice/relaxation therapy; formal psychotherapy and botulinum toxin injections are used less often, and botulinum toxin appeared less effective than in focal laryngeal dystonia.
Moderate evidence.
Caveats
Descriptive treatment-given data from one clinic, not a controlled efficacy comparison; 2 of 5 laryngospasm patients given botulinum toxin ultimately required tracheotomy, but n is too small to attribute this to the treatment.
What you can do / Self-reported survey
If you are allergic to a fragrance or preservative chemical, reading cosmetic ingredient labels is genuinely difficult, not just for you: in one clinical survey, 46% of patch-test-confirmed allergic patients found it difficult or extremely difficult, and this was significantly worse for people with less education.
Moderate evidence: Single-country (Danish), 3-clinic, self-rated VAS survey of 382 patients; not replicated elsewhere, so per our grading rule it stays below strong.
What you can do / Self-reported survey
People allergic to formaldehyde or methyldibromo glutaronitrile (MDBGN) have an especially hard time reading ingredient labels, likely due to long chemical names and formaldehyde's many synonyms and releasers; ask a dermatologist to write down or print the specific names and synonyms to watch for.
Moderate evidence: Single Danish survey; the mechanism (long/unfamiliar names) is the authors' plausible explanation, not directly tested.
What you can do / Self-reported survey
Many allergic patients who read ingredient labels still don't fully trust them: in one study only about half of patients affirmatively agreed that ingredient labels are accurate, so persistent reactions despite careful label reading are not necessarily a reading mistake.
Moderate evidence: Self-reported trust, not a test of actual label accuracy; the study does not adjudicate whether distrust reflects real label errors or post-hoc reasoning from continued reactions.
What you can do / Self-reported survey
Difficulty reading ingredient labels is a general problem across contact-allergic patients, not one limited to people with several different allergies, so simplifying label-reading advice would help broadly rather than only a small multi-allergic subgroup.
Moderate evidence: Single Danish survey (n=382); multiple-allergy status was defined only across the study's 7 target allergens.
What you can do / Measured in people or real products
A fading chemical smell is not a sign that exposure or irritation has stopped: PGME-exposed subjects lost the ability to smell the compound after about 3 hours at 250 ppm, while eye and nose irritation continued or worsened in those who stayed in the chamber.
Moderate evidence: Demonstrated only for PGME vapor at occupational-accident-level concentrations (hundreds of ppm), not for consumer-level scented product exposure.
Source: Stewart 1970 (Arch Environ Health), Archives of Environmental Health: An International Journal Industry-funded Link to this fact
What you can do / Measured in people or real products
Switching from a fragranced to a fragrance-free laundry detergent cut the fragrance chemical D-limonene coming out of the dryer vent by up to 99.7% (mean 79.1%) within one month, in real households, with no extra cost or apparent inconvenience.
Moderate evidence.
Caveats
4 households switched, D-limonene only; one household's no-product baseline (machine run with no detergent) actually rose 70.3% after the switch, which the paper attributes to residual fragrance chemicals left in the machine or clothing; no statistical testing.
Source: Goodman 2019, Air Quality, Atmosphere & Health Link to this fact
What you can do / Measured in people or real products
Emptying a dryer's lint filter dry (by hand, vacuum or brush) instead of rinsing it under a tap appears to substantially cut how much textile microfiber ends up in wastewater; a modeled comparison in one study found roughly 12.6 times more fiber reaching water when the filter was rinsed than when the fluff was thrown in household trash.
Moderate evidence.
Caveats
This is the study's own arithmetic model combining its drying data with a prior washing-machine dataset from the same lab, not an independent before/after trial of the two disposal methods; single detergent and appliance models.
Source: Cummins 2023, PLOS ONE Industry-funded Link to this fact
What you can do / Measured in people or real products
Childcare rooms with more fresh-air exchange had lower levels of several of the chemicals measured.
Weak evidence: Bivariate correlations, 34 rooms.
What you can do / Measured in people or real products
Keep scented products closed and avoid old, long-opened ones: limonene and linalool became skin irritants after weeks of air exposure.
Weak evidence.
Caveats
Extrapolated from lab-oxidized neat material (10-20 weeks air exposure); product storage not tested by this paper. Two independent industry market surveys have now directly tested the specific mechanism this advice assumes (in-bottle oxidation with age) and both found it absent: Kern 2014 (39 aged fine fragrances + 29 antiperspirants, 9 months accelerated storage) and Natsch 2019 (104 products spanning fine fragrances, antiperspirants, creams and lotions, including two fine fragrances tracked 3-6 years at room temperature) both found no progressive hydroperoxide accumulation with age, and consumer-product doses 2-4 orders of magnitude below elicitation/sensitization thresholds. Both studies are industry-funded (IDEA consortium: Givaudan, Firmenich, IFF, IFRA) and not independently replicated by a non-industry group, and neither tests essential oils or raw materials (separately known to accumulate hydroperoxide) or every product category. Moved to claims-to-avoid because the specific mechanistic basis for this advice (in-container autoxidation) is now negative in the only two real-product tests that exist, even though the underlying autoxidation chemistry itself, in neat/essential oils, is not disputed. Kern 2014 and Natsch 2019 are both industry studies (Givaudan / IDEA consortium) with Natsch as a co-author on both, so they are not independent replications of each other.
Source: Bråred Christensson 2009, Contact Dermatitis Industry-funded Link to this fact
What you can do / Review of other studies
Old, long-opened scented products are more allergenic than fresh ones, because the scent chemicals oxidize on contact with air.
Weak evidence.
Caveats
Time course is primary for lavender oil (Hagvall 2008: LLNA EC3 36% fresh -> 23% at 10 weeks -> 4.4% at 45 weeks in the same batch), but in neat oil in open lab flasks, not formulated products as stored. Kern 2014 first closed part of this gap (39 fine fragrances + 29 antiperspirants, no accumulation over 9 months accelerated storage); Natsch 2019 extends this to 104 products across more categories (adding limonene, creams, lotions) and to multi-year real-time storage (two fine fragrances tracked 3-6 years at room temperature, no accumulation), plus tests products donated by allergic patients themselves (also negative for hydroperoxide). Downgraded to avoid because the specific claim — that aging/opening itself makes a product more allergenic via in-container oxidation — has now failed two independent, broader industry market surveys with no non-industry evidence on the other side; creams, lotions and fine fragrances/antiperspirants are covered, though essential oils, raw materials and other categories remain untested and are not covered by this downgrade. Kern 2014 and Natsch 2019 are both industry studies (Givaudan / IDEA consortium) with Natsch as a co-author on both, so they are not independent replications of each other.
Source: Karlberg & Lepoittevin 2021, Contact Dermatitis Link to this fact
What you can do / Self-reported survey
People affected by fragrance say policies work only with purchasing rules for fragrance-free, low-emission products, staff education, better ventilation, and consequences for repeat violations, enforced like smoke-free rules.
Weak evidence: Participants' and authors' proposals; not tested as an intervention.
Source: Roy 2026 Link to this fact
What you can do / Hypothesis
Air a room or clean it instead of scenting it: non-chemical alternatives such as opening windows and better hygiene are the first step in Klaschka's ten-step hierarchy for reducing fragrance exposure.
Weak evidence: Expert recommendation; not tested in the paper.
Source: Klaschka 2020, Environmental Sciences Europe Link to this fact
What you can do / Review of other studies
If a child develops unexplained breast tissue, tell the doctor about every scented product the child uses or is near, including colognes, baby washes, hair products and diffusers; stopping them is what the case reports did.
Weak evidence: Practical advice drawn from case reports, not a tested intervention.
Source: Hawkins 2020, Complementary Therapies in Medicine Industry-funded Link to this fact
What you can do / Self-reported survey
People who always or usually used a healthy-product app, read ingredient labels or looked for eco-friendly labels used hair, skin and beauty products with somewhat lower EWG hazard ratings, by up to half a point on a 10-point scale.
Weak evidence: Cross-sectional; the rating is built from the same labels, so it cannot see undisclosed fragrance chemicals; no exposure measured.
Source: Barrett 2025, Journal of Exposure Science & Environmental Epidemiology Link to this fact
What you can do / Measured in people or real products
Using less shower product and running the bathroom fan both lower the fragrance-terpene peak: emissions scaled with product amount, and halving ventilation raised the modeled limonene peak from about 375 to 495 ppb.
Weak evidence: Amount-scaling from one person's shower; ventilation effect is modeled; no health outcome measured.
What you can do / Test-chamber measurement
Keeping indoor ozone low (no ozone-emitting 'air purifiers' or ionizers) limits both skin-oil chemistry and fragrance-terpene chemistry indoors, because ozone starts both chains.
Weak evidence: This paper makes no recommendation; the ozone-generator advice comes from Singer 2006, and the ventilation/ozone trade-off is our inference.
What you can do / Review of other studies
If you want to avoid persistent fluorinated ingredients, check cosmetic labels for 'PTFE', 'polytetrafluoroethylene', or names containing 'perfluoro-' or 'polyfluoro-'.
Weak evidence.
Caveats
Namazkar 2024 found INCI names for PFAS ingredients can themselves be ambiguous or incorrect (an apparent isomer mismatch for a silane; an undisclosed shorter chain-length range for a phosphate ester), and found unlabeled residual PFCA impurities in nearly every PFAS-containing cosmetic tested (5 of 6 products), which were far more dermally bioaccessible (43-76%) than the labeled ingredient itself (negligible bioaccessibility). Label-reading is a reasonable screen for intentionally added, correctly-named PFAS but does not detect the unlabeled residual impurities this paper shows can be present and bioaccessible regardless of which PFAS is named.
Source: Jomaa 2024, Journal of the Netherlands Society of Toxicology (JNST) Industry-funded Link to this fact
What you can do / Lab study (cells or chemistry)
Only 6 of 42 perfumes tested were comparatively low in hazardous compounds across ten lab tests, which suggests lower-hazard perfumes can be made.
Weak evidence: Products not named, so consumers cannot identify the cleaner ones; in vitro only.
Source: Morlock & Heil 2025, Journal of Chromatography A Link to this fact
What you can do / Instrument measurement
A filter-only HEPA air purifier kept fine-particle readings near zero after hair and nail products were used together in a small closed room.
Weak evidence: Flow-to-volume ratio far above any real home or salon; VOC removal by the carbon filter not credible for acetone/formaldehyde.
What you can do / Review of other studies
Fragrance-free policies are easier to make work when they start with a needs assessment and an inventory of the cleaning and personal products in use, involve employees in drafting, and agree how violations are handled before launch.
Weak evidence: Lessons from unnamed organizations; no outcome data.
What you can do / Review of other studies
Close fragranced products after use and discard them about a year after opening to limit exposure to oxidized allergens.
Weak evidence.
Caveats
Expert advice; no study tests whether it reduces dermatitis. The assumed mechanism (in-bottle oxidation during storage) has now failed two industry market surveys rather than one: Kern 2014 (fine fragrances, antiperspirants, 9 months accelerated storage) and Natsch 2019 (104 products including creams and lotions, two fine fragrances tracked 3-6 years at room temperature) both found no hydroperoxide accumulation with age or storage time. The advice may still be reasonable for essential oils and raw materials (which do carry hydroperoxide, e.g. lavandin ~220 ug/g), just not via this specific in-bottle mechanism for finished consumer products. Both studies are industry-funded (IDEA consortium: Givaudan, Firmenich, IFF, IFRA) and not independently replicated, and say nothing about essential oils, raw materials or product categories outside fine fragrances/antiperspirants/creams/lotions. Kern 2014 and Natsch 2019 are both industry studies (Givaudan / IDEA consortium) with Natsch as a co-author on both, so they are not independent replications of each other.
Source: Pastor-Nieto 2021 (Klaschka 2010), Current Treatment Options in Allergy Link to this fact
What you can do / Measured in people or real products
Moisturizers that listed alcohol or 'alcohol denat.' near the top of the ingredient list delivered far more ethanol to a mannequin's nose; products with no listed alcohol gave almost none.
Weak evidence: 16 products, qualitative (Fig. 4, no statistic); ethanol hidden inside 'parfum' is not visible on labels; absolute ethanol doses are disputed.
What you can do / Measured in people or real products
'Agua de violetas' colognes marketed to Hispanic families, including preparations made for babies, are a specific consumer product worth asking about if a young child has unexplained breast growth.
Weak evidence: Based on 2 of 3 case reports from one clinic; not every bottle sold under this name contains lavender oil.
Source: Diaz 2016, Journal of Pediatric Endocrinology and Metabolism Link to this fact
What you can do / Hypothesis
If you already notice fragrance-related symptoms, do not expect awareness alone to change your exposure — most Germans who link their own symptoms to fragrance still use fragranced products at or above the average rate; choosing fragrance-free products and spaces is the step that actually reduces exposure.
Weak evidence: Author's recommendation, drawn from the self-exposure paradox in this survey; not itself tested as an intervention.
Source: Klaschka 2020a, Environmental Sciences Europe Link to this fact
What you can do / Review of other studies
If households switch from fragranced to fragrance-free laundry detergent, modeling suggests dryer-vent limonene emissions across a whole city or state could drop substantially — an estimated 1.58 tons per year for metropolitan Melbourne, or 8.66 tons per year for the state of California.
Weak evidence.
Caveats
This is a modeled extrapolation, not a measurement: it multiplies a mean vent concentration from just 2-6 households (one grab sample each) by census household counts and usage-rate assumptions, with no confidence interval or sensitivity analysis anywhere in the calculation; the Melbourne input is dominated by a single outlier household roughly 11 times the other three.
Source: Goodman, Nematollahi & Steinemann 2020/2021, Air Quality, Atmosphere & Health Link to this fact
Information, not medical advice. See also: myths we won’t tell you.