Don’t take our word for it. Here’s every fact on this site, with its evidence grade, its caveats, and a link to the source, so you can check us.
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.
Hidden ingredients / Other evidence
EWG Verified permits fragranced products: its criteria require fragrance components to be disclosed to EWG, not fragrance to be absent.
Moderate evidence: A rulebook, not a test; it reports no data on products. EWG is an advocacy nonprofit that also licenses the mark.
Source: EWG 2026, EWG program criteria (PDF) Link to this fact
Hidden ingredients / Other evidence
Under EWG Verified, a product's website must list every fragrance ingredient above 100 ppm, or the first five by concentration if none exceeds 100 ppm; the package may show only the word 'Fragrance' with a website pointer (not allowed for fine fragrance).
Moderate evidence: Fragrance components below 100 ppm in a mixture that has a larger component need not be published. EWG's own design, not law.
Source: EWG 2026, EWG program criteria (PDF) Link to this fact
Hidden ingredients / Other evidence
OEKO-TEX took p-anisidine off its 'under observation' list for arylamines and gave it a limit of 20 mg/kg (100 mg/kg for ECO PASSPORT), and removed methylisothiazolinone from its observation list in 2026.
Moderate evidence.
Caveats
Promotion of p-anisidine is inferred from two documents; the notice does not say that removal of MIT from observation means a limit; MIT's former status was not found in the 2025 table text.
Source: OEKO-TEX Association, Limit values: New regulations 2026 (customer information, 03.03.2026) Industry-funded Link to this fact
Hidden ingredients / Other evidence
EWG says a cleaning product's A-F grade is not an average of its ingredients' grades: it also counts how fully the maker discloses ingredients, any EWG-approved green certification, and the hazards of the formulation as a whole.
Moderate evidence: This is EWG describing its own method; the formula and weights are not given, and the 2012 method may have changed.
Source: Andrews, EWG, 2012 (web page) Link to this fact
Hidden ingredients / Other evidence
In EWG's cleaning-product grading, an ingredient with little or no public hazard information gets a C, and EWG says lack of safety data is the most common reason an ingredient gets a C.
Moderate evidence: A C therefore often means 'no public data', not 'found hazardous'. Self-described method; no ingredient counts given.
Source: Andrews, EWG, 2012 (web page) Link to this fact
Hidden ingredients / Other evidence
When only a chemical class (not the specific chemical) is known, EWG's cleaning-product method scores the ingredient as the most hazardous chemical in that class.
Moderate evidence: Self-reported rule; the article does not say how often it is applied.
Source: Andrews, EWG, 2012 (web page) Link to this fact
Hidden ingredients / Other evidence
EWG states that the words 'fragrance' or 'parfum' on a label mark blends of ingredients that companies are not required to disclose, and that some may be safe but the blends could also contain potentially harmful ingredients.
Moderate evidence: Statement of EWG's position; consistent with our regulatory pages but no new evidence here.
Source: EWG 2025 (Friedman & Huang), EWG news (web page) Link to this fact
Hidden ingredients / Journalism
Skin Deep's published method gives "fragrance" and unidentified essential oils a flat top score of 100 in a category for ingredients "not fully identified"; it does not look inside the fragrance, so a blend with phthalates and one without score the same.
Moderate evidence.
Caveats
Stated in one sentence under an apparently misplaced table heading, and the page does not say how the flag combines with the other categories in the final 1-10 number. The "same score" part is inferred from the absence of any constituent step.
Source: EWG Skin Deep methodology page (2026 capture) Link to this fact
Hidden ingredients / Other evidence
EWG says an ingredient with no safety data can score as low as a known safe one (1-2 of 10) in Skin Deep, so a low hazard score can simply mean nobody has studied it.
Moderate evidence: Self-description by the score's author; EWG advises choosing at least 'fair' data availability.
Source: EWG, Skin Deep FAQ (web page, accessed 2026-10-16), EWG web page (Skin Deep FAQ) Link to this fact
Hidden ingredients / Other evidence
EWG scores generic 'fragrance' at 8 out of 10 in Skin Deep because the ingredients are undisclosed and often include allergens and hormone disruptors.
Moderate evidence: The page gives no derivation of the 8 and no citation; it is an NGO judgment, not a measurement.
Source: EWG, Skin Deep FAQ (web page, accessed 2026-10-16), EWG web page (Skin Deep FAQ) Link to this fact
Hidden ingredients / Other evidence
A personal care product can be EWG Verified even if some of its ingredients do not score green on Skin Deep; EWG requires the overall product score to be green.
Moderate evidence: EWG's own FAQ; the scoring method is described elsewhere and was not reviewed here.
Source: EWG Verified FAQ, verified-portal.ewg.org, accessed 2026-10-16, EWG Verified portal web page Link to this fact
Hidden ingredients / Other evidence
EWG's FAQ says Verified accepts proprietary trade-name ingredients but requires all ingredients to be disclosed on the label and website; the criteria document narrows this for fragrance, listing only components above 100 ppm (or the top five) publicly.
Moderate evidence.
Caveats
The FAQ never mentions fragrance; the 100 ppm detail comes from the sibling criteria page. The two texts are consistent only if 'all ingredients' means all label ingredients, with fragrance listed as a mixture.
Source: EWG Verified FAQ, verified-portal.ewg.org, accessed 2026-10-16, EWG Verified portal web page Link to this fact
Hidden ingredients / Other evidence
The EU's cosmetics committee noted in 2010 that powder hair dye containing 30% sodium perborate monohydrate would have to be labeled 'Toxic' and would not be generally available to consumers if sold as another type of product.
Moderate evidence: The committee's remark about the supplied powder, not a labeling finding about any marketed product.
Source: SCCS 2010 (SCCS/1345/10), SCCS opinion SCCS/1345/10 (PDF) Link to this fact
Hidden ingredients / Other evidence
In the Pew authors' reading of US food rules, flavors and spices can appear on a food label without their chemical or common names, and a vertically integrated manufacturer can keep its GRAS decision internal; the authors say several large manufacturers told them they use this approach.
Moderate evidence: The manufacturer statements are anecdotal and unnamed; applies to food, not cosmetics or fragrance.
Source: Neltner et al. 2011, Compr Rev Food Sci Food Saf, Comprehensive Reviews in Food Science and Food Safety Link to this fact
Hidden ingredients / Government agency
The EU committee judged chloroatranol and atranol, the main allergens in oak moss and tree moss extracts, not safe in cosmetic products; it quoted an elicitation threshold for chloroatranol of 0.0004 micrograms per square centimeter, about 2,000 times lower than its general 0.8 figure.
Moderate evidence.
Caveats
Chloroatranol threshold comes from a small experimental dose-elicitation study in already-allergic people; the committee states that content-reduction efforts for oak moss had largely failed to reduce allergy.
Hidden ingredients / Other evidence
Polysorbate 60 was reported in 1,589 cosmetic products in 2015, up from 332 in 1998, making it one of the three most-used polysorbates after polysorbate 20 (3,013) and polysorbate 80 (932).
Moderate evidence: Voluntary registration counts, not sales volume; counts include products reported under the alias 'PEG-20 sorbitan stearate' only separately.
Source: CIR 2015 draft Industry-funded Link to this fact
Hidden ingredients / Other evidence
The CIR draft contains no discussion of hydrogen peroxide reacting with terpenes or fragrance materials; it reports peroxide reacting with oxidative hair dye precursors, leaving little residual peroxide in the applied dye.
Moderate evidence: Absence of text in a cosmetic-ingredient safety draft, not evidence of no interaction.
Source: CIR 2018 draft (Do Not Cite or Quote; PCPC-funded CIR) Industry-funded Link to this fact
Hidden ingredients / Other evidence
Wet cleaning rests on water, but the detergents and spotting agents hold alcohol ethoxylates, glycol ethers, D-limonene, monoethanolamine, quaternary ammonia and trade secrets; many safety data sheets lacked ingredient data, some noted skin and eye irritation, and ethoxylated alcohols can carry 1,4-dioxane (county study pending).
Moderate evidence: From the county's review of a sample of safety data sheets, not testing of products or garments; the report still rated wet cleaning health-green.
Source: SCDHS 2018 Link to this fact
Hidden ingredients / Other evidence
The hydroperoxides that cause this allergy are not listed on labels, so patients can only look for limonene and linalool, two of the 26 EU-declarable fragrance allergens.
Moderate evidence: Authors' statement about labeling in the EU; limonene and linalool on a label show the parent chemical, not whether any hydroperoxide is present.
Source: Dittmar & Schuttelaar 2019, Contact Dermatitis Link to this fact
Hidden ingredients / Other evidence
IARC states that because accurate measurement is hard, asbestos contamination of talc 'may still be a concern' and may expose workers and the general public, for example through contaminated talc-based make-up and body powder.
Moderate evidence: A statement of concern, not a measured contamination rate; no product testing data in the release.
Source: IARC Press Release 352 (2024) Link to this fact
Hidden ingredients / Review of other studies
Sulfites, a preservative that can cause skin allergy, are found in many medicines you would not suspect: topical steroids, antibiotics, antifungals, hemorrhoid creams, local anesthetics, catheter gel, and 3.8% of 264 ophthalmic medications checked.
Moderate evidence: Narrative review; the 3.8% figure comes from a single analysis of prescription eye products, and the other medicines are case reports, not prevalence.
Source: Choi 2024, Cutis Link to this fact
Hidden ingredients / Other evidence
Hair dye is a major sulfite source: sulfites are listed in as many as 90% of hair dye kits in the ACDS Contact Allergen Management Program database.
Moderate evidence: The 90% is a ceiling ('as many as') from a database run by the same society; the review gives no denominator.
Source: Choi 2024, Cutis Link to this fact
Hidden ingredients / Other evidence
At one South Los Angeles Target, 70% of 150 products in Target's "Clean" tier for textured hair listed "fragrance" or "parfum", an umbrella term that does not reveal what is in it.
Moderate evidence: Label audit of one store's online listings (Sept 2022); no chemical testing, and one store is not all Target stores or products as sold today.
Source: Madrid Larrañaga 2026, Journal of Exposure Science & Environmental Epidemiology Link to this fact
Hidden ingredients / Other evidence
Only 41% (62 of 150) of the "Clean" textured-hair products at this Target had a score in EWG's Skin Deep database, and none carried the EWG Verified mark, so most could not be looked up.
Moderate evidence: One store, scraped 2022 and matched to EWG in 2023; how products were matched is not described, and how scored and unscored products differ is unknown.
Source: Madrid Larrañaga 2026, Journal of Exposure Science & Environmental Epidemiology Link to this fact
Hidden ingredients / Other evidence
Among 62 scored "Clean" textured-hair products, EWG's Skin Deep scores averaged 4.1 and 90% fell in the "moderate" 3-6 band; in 18 case-study products the top-scoring ingredient was fragrance or a fragrance-type ingredient in most.
Moderate evidence: A score built from disclosed ingredients with fragrance flat-scored, not measured hazard or exposure; no non-"clean" comparison; the 18 were chosen to span scores.
Source: Madrid Larrañaga 2026, Journal of Exposure Science & Environmental Epidemiology Link to this fact
Hidden ingredients / Government agency
FDA's proposal says the voluntary system left it unable to see some GRAS uses: it cites stevia leaves and crude extracts and ashwagandha (Import Alert 99-45, 2023, 'has not been the subject of a voluntary GRAS notice') as uses it dealt with without a GRAS notice.
Moderate evidence: FDA's own account of two examples; they illustrate the gap but do not measure it. Proposal stage; stevia and ashwagandha are not fragrance or cosmetic ingredients.
Source: FDA 2026, 91 FR 51834 (proposed) Link to this fact
Hidden ingredients / Measured in people or real products
All 17 everyday product perfumes (shampoos, baby bath, lotions, deodorants) contained at least one of the fragrance-mix allergens by GC-MS, about 2.6-2.8 on average; geraniol was in 12 of 17.
Moderate evidence: Single manufacturer's lower-priced perfumes, 1990s Denmark; oak moss not analyzed; concentrations are in the perfume, not the finished product.
Source: Johansen 1997, Contact Dermatitis Link to this fact
Hidden ingredients / Measured in people or real products
In the 17 product perfumes the quantified fragrance-mix allergens ranged from about 0.005% to 1.35% w/v of the perfume, with the highest being amyl cinnamal (1.35%) in a creme rinse perfume and eugenol 0.39% in the same perfume.
Moderate evidence: Concentration in the perfume concentrate, not in the finished product; some entries detected but not quantifiable due to interference.
Source: Johansen 1997, Contact Dermatitis Link to this fact
Hidden ingredients / Other evidence
About half of patients and doctors (52%, 353 of 678) did not suspect a cosmetic as the cause of the dermatitis until investigation.
Moderate evidence: Single multicenter series of specialist dermatologists, 1977-1983.
Source: Adams & Maibach 1985, Journal of the American Academy of Dermatology Link to this fact
Hidden ingredients / Other evidence
Limonene, linalool and Lyral are fragrance ingredients commonly found in personal care products, processed foods and beverages, and perfumes, and the society judges them relevant for many patch-tested patients.
Moderate evidence: Committee judgment based on cited reviews; no product-survey data in this paper.
Hidden ingredients / Review of other studies
Mixing sodium hypochlorite bleach with ammonia releases chloramines, and mixing it with acids releases chlorine; the review lists both among exposures that cause irritant-induced asthma.
Moderate evidence: Cause is listed from case reports and series; no dose data, and mostly occupational.
Source: Lemiere 2022, The Journal of Allergy and Clinical Immunology: In Practice Link to this fact
Hidden ingredients / Measured in people or real products
About half of cosmetic dermatitis cases (241 of 460, 52%) were not suspected by the patient or the doctor to be cosmetic-related before testing.
Moderate evidence: Selected referral series of contact dermatitis specialists, 1977-1980 (40 months); not general-population rates; one multicenter series, same group as Adams 1985 (not independent).
Source: Eiermann 1982, Journal of the American Academy of Dermatology Link to this fact
Hidden ingredients / Other evidence
Three studies found 28%, 17% and 23% of skin creams labeled incorrectly against the specific legislation, and 46% of allergic participants had difficulty reading cosmetic labels, so an ingredient list does not guarantee that a preservative allergy can be avoided.
Moderate evidence: Older, small Scandinavian and Korean product surveys; the review does not say what the errors were.
Hidden ingredients / Other evidence
Almost 9 in 10 (88%, 57 of 65) top-rated Amazon sunscreens carried extra claims such as sensitive skin, preservative-free, natural or organic; the authors call these marketing claims, not performance standards.
Moderate evidence: Claims were recorded as printed; no ingredient lists were checked against them in this paper.
Hidden ingredients / Government agency
In a screening-level EPA estimate for commercial food-contact hard surfaces, chronic dietary exposure from ADBAC at the maximum label rates exceeded the chronic reference dose for infants (about 400% at 16,000 ppm with a water rinse; about 260% at 4,900 ppm without one) and young children, but not at the 400 ppm tolerance exemption (infants 21%).
Moderate evidence.
Caveats
Screening assumptions: maximum label concentration, 44.3% transfer from surface to food, no measured food residues; EPA calls the label rates well above the tolerance exemption and does not state that real exposure exceeds the dose.
Source: US EPA 2017 Link to this fact
Hidden ingredients / Other evidence
21 CFR 101.22 itself says nothing about allergens: the duty to name a major food allergen inside a flavor, spice or color comes from FD&C Act section 403(w) (FALCPA), and covers only the listed major allergens.
Moderate evidence: Absence-of-text finding for this section; the allergen rule itself is cited from our FALCPA and FDA Q&A pages, not from this document.
Source: 21 CFR 101.22 (eCFR 2026), Code of Federal Regulations, Title 21, Section 101.22 (eCFR) Link to this fact
Hidden ingredients / Other evidence
Benzyl alcohol can be labeled as a preservative rather than a fragrance, so products labeled 'fragrance-free,' 'clean,' 'sensitive' or 'hypoallergenic' may contain it; these marketing terms have no federal definition in the US.
Moderate evidence: Narrative review; legal reading by dermatologists; no systematic sample of 'fragrance-free' products. Consistent with the 2007 column.
Source: Zheng et al. 2026, ACDS Allergen of the Year (Cutis), Cutis Link to this fact
Hidden ingredients / Other evidence
A 2022 study found benzyl alcohol in 15.8% of 1,470 skin care products labeled clean, natural, organic or hypoallergenic.
Moderate evidence: Secondary citation; the figure is for those four label terms, not specifically 'fragrance-free'; product sampling frame not described here.
Source: Zheng et al. 2026, ACDS Allergen of the Year (Cutis), Cutis Link to this fact
Hidden ingredients / Other evidence
Tobacco makers add flavor, casing and humectant ingredients (licorice, honey, molasses, coumarin, glycerol), and the cigarette-industry authors of a leading smoke-chemistry catalog say that how most added ingredients transfer into smoke has been examined for very few of them.
Moderate evidence: Industry authors' own statement; the additives chapter itself is not in this PDF.
Source: Rodgman & Perfetti 2013 Industry-funded Link to this fact
Hidden ingredients / Other evidence
Patch-test reactions to formaldehyde-releasing preservatives (quaternium-15 3.6%, bronopol 1.3%, imidazolidinyl urea 1.1%, DMDM hydantoin 0.8%) were significantly lower in 2015-2016 than the 2005-2014 pooled rates while reactions to formaldehyde itself rose to 8.4% (2% aq), and preservative substitution toward MI was expected by the authors to keep changing sensitization rates.
Moderate evidence: The authors attribute the fall to companies dropping releasers but cite only a company web page; no product-level data.
Hidden ingredients / Review of other studies
A 2021 consensus essay names diethyl phthalate (DEP) and dibutyl phthalate among phthalates used in nail polish, lotions, fragrances and hair-styling products, and says studies show personal-care-product use tracks with urinary phthalate metabolites.
Moderate evidence: One sentence citing a single exposure study (Berger and colleagues); no concentrations given; fragrance is mentioned only in that list.
Source: Engel 2021, American Journal of Public Health Link to this fact
Hidden ingredients / Lab study (cells or chemistry)
In lab tests on human cells, four fragrance musks (including Galaxolide and Tonalide) blocked the progesterone receptor; Tonalide (AHTN) and Phantolide (AHMI) did so at about 0.02 µM, the strongest effect in the study, and Galaxolide (HHCB) at 0.2 µM.
Moderate evidence.
Caveats
Cell-reporter assay, single compounds, one lab, test-tube concentrations; no animal or human data and no comparison with body levels. Two authors work at the company that sells the assay.
Source: Schreurs 2005, Toxicological Sciences Link to this fact
Hidden ingredients / Review of other studies
Galaxolide and Tonalide are used in perfumes, cleaning products, detergents and cosmetics, so they are typically covered by the single word 'fragrance' on a label.
Moderate evidence: Statement is in the paper's introduction and describes use, not what any given label discloses; this study measures no exposure.
Source: Schreurs 2005, Toxicological Sciences Link to this fact
Hidden ingredients / Other evidence
In a 2005 lab study on mussel gill tissue, six synthetic musks used as fragrance ingredients, including musk xylene, musk ketone, galaxolide and tonalide, blocked the cell's pump that expels foreign chemicals, at micromolar concentrations.
Moderate evidence.
Caveats
Ex-vivo marine mussel gill, one lab, n=3-7 animals per compound, one dye assay; no human cells or exposures; effective concentrations exceed measured water levels and the authors' estimate of human body burdens.
Source: Luckenbach 2005, Environmental Health Perspectives Link to this fact
Hidden ingredients / Other evidence
The 'white musk' scent oil tested in a 2025 Japanese lab study was a blend of synthetic fragrance ingredients: its largest peak was linalool (11.9% of GC peak area), then hedione (8.3%), galaxolide (5.2%), hexyl cinnamal (4.6%), benzyl acetate (3.7%) and tonalide (1.6%), with galaxolide at 34.8 mg/mL and tonalide at 15.0 mg/mL in the neat oil.
Moderate evidence: One product from the study's own co-developer, one analysis; percentages are peak areas, not weight; other peaks were not identified; other 'white musk' products may differ.
Source: Zennifa 2025, Scientific Reports Industry-funded Link to this fact
Hidden ingredients / Other evidence
The fragrance terpenes in the restroom's urinal screens (alpha-terpinene, linalool, limonene, linalyl acetate and others, about 20 ppb total in one test) were the main chemicals that reacted with the lamp-made ozone.
Moderate evidence: Single room; deodorizer screens, not household fragrance; alpha-terpinene dominance is specific to this product.
Source: Link 2024, Environmental Science: Processes & Impacts Link to this fact
Hidden ingredients / Other evidence
Limonene and beta-pinene scent terpenes were measurable in every perfume, deodorant and cleaning liquid tested (about 0.1-0.3% and 0.04-0.65% of product weight), even though labels only say 'fragrance' or, for the cleaners, name limonene.
Moderate evidence.
Caveats
Six products; GC-MS of three terpenes only, so other scent chemicals are unmeasured; alpha-pinene was below the detection range. The abstract's beta-pinene range (0.4-0.7%) differs from Table 1 (0.04-0.65%).
Indoor air / Self-reported survey
19.4% of Australians reported health problems from being near someone wearing fragrance and 16.4% from air fresheners.
Moderate evidence: Self-report; no exposure measurement; counts 213/1,098 and 180/1,098 confirmed in Steinemann 2018 (MCS, AU) Table 2, same dataset.
Source: Steinemann 2017, Preventive Medicine Reports Link to this fact
Indoor air / Self-reported survey
About 1 in 6 adults (17%) in four countries said air fresheners or deodorizers make them unwell; of those, half reported breathing problems.
Moderate evidence: Self-report, no objective measure.
Source: Steinemann 2019, Air Quality, Atmosphere & Health Link to this fact
Indoor air / Self-reported survey
41% of US adults with asthma reported health problems from air fresheners, and 36.7% said they can't use a public restroom that has one.
Moderate evidence: Self-report.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
Indoor air / Self-reported survey
23.5% of Swedes reported health problems from being near someone wearing a fragranced product.
Moderate evidence: Self-report.
Source: Steinemann 2018 (Sweden), Air Quality, Atmosphere & Health Link to this fact
Indoor air / Self-reported survey
About 1 in 5 US adults (20.4%) reported health problems from air fresheners, and 23.6% from being near someone wearing a fragranced product.
Moderate evidence: Self-report; no exposure measurement.
Source: Steinemann 2016, Air Quality, Atmosphere & Health Link to this fact
Indoor air / Self-reported survey
About 1 in 5 Australians with asthma (21.4%) said they can't or won't use public toilets that have air fresheners.
Moderate evidence: Self-report.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
Indoor air / Measured in people or real products
Scented laundry products put fragrance chemicals into outdoor air: in two homes, limonene (a citrus scent chemical) came out of the dryer vent only when fragranced detergent or dryer sheets were used (up to 14.7 ug/m3), not in the no-product runs.
Moderate evidence.
Caveats
2 homes (Steinemann 2013), single grab samples; undiluted vent air, not a breathing-zone dose. Replicated at much higher magnitude and with a dose-response signal by Goodman et al. 2019 (6 Melbourne homes, before/after switch design): fragranced-detergent vent D-limonene 2.35-118 ug/m3 vs 0.24-0.26 ug/m3 in fragrance-free-only homes, and switching from fragranced to fragrance-free detergent cut vent D-limonene by up to 99.7% (mean 79.1%) within a month. The two studies share one author (Anne Steinemann) and neither ran statistical significance tests, so the combined evidence (8 homes total) stays below strong, but the qualitative and dose-response finding is now cross-country replicated within one research program rather than resting on a single 2-home study.
Source: Steinemann 2013, Air Quality, Atmosphere & Health Link to this fact
Indoor air / Measured in people or real products
In a room-sized test chamber, mopping with a pine-oil cleaner or spraying an orange-oil degreaser, with ozone at typical summer-smog levels, produced 130-280 µg/m³ of fine particles, versus 2-5 µg/m³ when the same products were used without ozone.
Moderate evidence.
Caveats
Chamber, 1 product per type, 120 ppb ozone supply; real homes measured lower SOA mass. Corroborated in a second, smaller chamber with the same products (Destaillats 2006 bench-scale: steady-state SOA mass 11-229 µg/m³, same order of magnitude), but that study shares the same research group, products, and contract, so it does not count as independent replication.
Source: Singer 2006, Atmospheric Environment Link to this fact
Indoor air / Measured in people or real products
Scent chemicals in cleaners and air fresheners react with ozone that drifts in from outdoors to make formaldehyde: cleaning raised formaldehyde by 9-16 ppb for 4 hours, and a plug-in air freshener raised it by about 6 ppb for as long as it ran.
Moderate evidence.
Caveats
Secondary formation only, depends on indoor ozone. The underlying mechanism is now directly quantified at bench scale (Destaillats 2006: formaldehyde 16-38% per ozone consumed for the same three products), but that bench study is the same research group/products/contract as this one, not an independent replication, so the grade is not raised on that basis alone.
Source: Singer 2006, Atmospheric Environment Link to this fact
Indoor air / Measured in people or real products
After 2-7 minutes of cleaning with a terpene cleaner, indoor air chemistry stayed altered for 10-12 hours because the scent chemicals soaked into walls and floors and came back out.
Moderate evidence.
Caveats
Empty chamber; furnished rooms may differ. Singer 2006 (Indoor Air primary-emissions companion, same 50 m3 room without ozone) corroborates the sorption/desorption mechanism directly: alpha-terpineol stays at 260-700 ug/m3 for hours and ~90 ug/m3 at 4-24 h via surface water films and wallboard sorption, and towels left in the room raise 24-h emissions 35-100%. Not independent (same lab/room/products as the ozone paper).
Source: Singer 2006, Atmospheric Environment Link to this fact
Indoor air / Measured in people or real products
In a European study that measured the air 182 adults actually breathed over 48 hours, exposure to pine- and citrus-type scent chemicals from cleaning products and fragrances rose with the number of children at home (3-carene median 0.9 to 2.5 µg/m³); the authors attribute this to more cleaning.
Moderate evidence: Late-1990s, small subgroups, attribution to cleaning is the authors' inference; CEFIC-LRI co-funded.
Source: Edwards 2006, Atmospheric Environment Industry-funded Link to this fact
Indoor air / Self-reported survey
Air fresheners were the most common secondhand trigger: 15.5% of UK adults reported health problems from them, and 12.1% avoid or are reluctant to use public restrooms that have them.
Moderate evidence: Self-report.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
Indoor air / Measured in people or real products
Keeping a gel air freshener in a car raised the fragrance chemical limonene in the air the driver breathed 3.6-4.7 times, to about 19-28 ug/m3, during real commutes (10 cars tested).
Moderate evidence: N=5 per group, non-randomized; mostly drivers' own products.
Information, not medical advice. See also: myths we won’t tell you.