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.
Children and pregnancy / Self-reported survey
Household ammonia use was the only one of 10 individual cleaning agents (out of 30 agent-outcome comparisons) significantly associated with an outcome in this study: adolescents in homes where ammonia was ever used had lower odds of rhinitis, adjusted OR 0.60 (95% CI 0.44, 0.82), than those in homes that never used it.
Weak evidence.
Caveats
The study's own authors call this a likely chance finding given the number of associations tested and their limited statistical power to explore it further; not a basis for claiming ammonia protects against rhinitis.
Source: Bukalasa et al. 2019, Environment International Link to this fact
Fragrance is everywhere / Hypothesis
Immigrant women in the US most often work as house cleaners and make up 71% of manicurists; an expert job-exposure tool rates both jobs as probably exposed to fragrance chemicals, and house cleaning also to cleaning-product ingredients such as alkylphenols and antimicrobials.
Weak evidence: Exposure ratings from job descriptions (WORC), not measurements.
Source: Knox 2026, Journal of Exposure Science & Environmental Epidemiology Link to this fact
Fragrance is everywhere / Other evidence
About 65 percent of 500 randomly called Hong Kong households (323) said they had a dry-cleaning habit, and 93 percent of them keep the clothes in a wardrobe; 44 percent leave the cleaner's plastic bag on until they wear the item.
Weak evidence: Self-report, 1996 Hong Kong, random phone-book sample; not a measure of exposure.
Source: Chao 1998, Building and Environment Link to this fact
Green, natural and unscented / Other evidence
Study participants were given a free 'starter kit' of unscented cleaning products and 'alternative cleaning recipes' as part of a personalized action plan to reduce indoor VOC exposure, and researchers observed reduced use of scented products at follow-up visits.
Weak evidence.
Caveats
Product-use reduction was assessed by researcher observation during a scheduled visit, not by continuous monitoring, and patients knew they were being evaluated (compliance may be overstated).
Source: Rincón et al. 2024, Primary Health Care Research & Development Link to this fact
Green, natural and unscented / Test-chamber measurement
The limonene given off by a natural fragrant plant is the same chemical as the limonene in cleaners and air fresheners; in this study three plants took room limonene to about 60-84 ug/m3 on average over 3 hours, in the range of a plug-in air freshener and well below the 1,000-6,000 ug/m3 seen right after terpene cleaning in a chamber.
Weak evidence: Cross-study comparison of different averaging times and rooms; the 'after' means are back-calculated from the dose table; plug-in and cleaning values come from other studies.
Health effects / Hypothesis
Silent Spring Institute researchers name house cleaners and nurses as priority jobs for cutting exposure to fragrance, cleaning, and personal-care chemicals linked to breast cancer in lab and animal studies.
Weak evidence: No exposure or cancer data in these workers.
Source: Knox 2026, Journal of Exposure Science & Environmental Epidemiology Link to this fact
Health effects / Review of other studies
Many everyday chemicals, including some released by scented and cleaning products, act on the same irritant-sensor nerves in the nose and airways (TRPA1 and TRPV1), one reason very different products can cause similar symptoms.
Weak evidence: Mechanism largely from lab/animal studies; dose relevance to homes untested.
Source: Molot 2023, Neuroscience and Biobehavioral Reviews Link to this fact
Health effects / Review of other studies
Frequent private use of household disinfectants (a composite of methods including hand-wash, machine, sponge, and spray disinfection) was linked to close to a threefold increase in the odds of newly developing asthma in a single cross-sectional wave of young German adults (Weinmann 2017, OR 2.79, 95% CI 1.14-6.83); the evidence for household sprays alone driving that same result was already weak in that wave (OR 2.79, 95% CI 0.84-9.20), and a 10-year longitudinal follow-up of the same cohort (Pacheco Da Silva 2025) found no significant association between persistent spray-only use and current asthma or wheeze (point estimates at or below 1.0 for every outcome), with only a non-significant, attenuated OR of 1.68 (95% CI 0.48-5.88) for sustained use of multiple disinfectants/cleaning products together.
Weak evidence.
Caveats
Two analyses of the same German SOLAR cohort (Weinmann 2017's cross-sectional SOLAR II wave, and Pacheco Da Silva 2025's 10-year longitudinal follow-up adding SOLAR III with latent-class exposure profiles) now agree that spray-specific use is not significantly associated with adult asthma. The only positive signal across both papers is a composite 'persistent use of multiple DCPs' profile, which itself weakened from a significant OR 2.79 (single wave, simple frequency composite) to a non-significant OR 1.68 (10-year follow-up, latent-class model, wide CI 0.48-5.88). Both papers are single-cohort, self-reported-exposure studies from the same research group, so per the grading rule this stays below moderate. The follow-up nulls are underpowered (1,143 of the original 2,051; only ~8-12% in each persistent-use profile; CIs span roughly 0.5-6), so they weaken the claim without refuting it. Other cohorts not yet in our evidence base reported positive spray-asthma associations (ECRHS, Zock 2007; French EGEA, Pacheco Da Silva 2023); don't cite this cohort as evidence that sprays are safe.
Source: Salonen 2024, Environment International Link to this fact
Health effects / Self-reported survey
In a 10-year longitudinal follow-up of a German young-adult cohort (SOLAR, n=1,143), only participants who persistently used multiple disinfectants and cleaning products (sprays, disinfectant sprays, and nonspray disinfection methods) weekly at two assessments 10 years apart showed an elevated point estimate for current asthma (OR 1.68) and current wheeze (OR 1.71) compared with no weekly use; neither reached statistical significance (95% CI 0.48-5.88 and 0.75-3.90).
Weak evidence.
Caveats
Same underlying cohort as Weinmann 2017 (SOLAR 2 exposure data reused); small persistent-use subgroup (8.2% of n=1,143); wide confidence intervals; incident-asthma/wheeze estimates too imprecise for inference; authors draw no causal conclusion.
Health effects / Measured in people or real products
In the same chamber study, particles formed when the citrus fragrance chemical d-limonene reacted with ozone tended to shift that same heart-rhythm marker in the opposite direction from candle smoke, at particle levels similar to everyday cleaning or air-freshener use.
Weak evidence.
Caveats
This tendency was not statistically significant on its own versus clean air (HF -7.2%, p=0.41); only its difference from candle smoke's opposite-direction change reached significance (p=0.02, 12-subject paired comparison). Not replicated.
Source: Hagerman et al. 2014, Atmospheric Environment Link to this fact
Health effects / Other evidence
The TVOC and PM2.5 increases measured after cleaning in this study (up to about 104 ppbv and 14.5 micrograms per cubic meter) fall at the lower end of ranges reported elsewhere for cooking (10-560 ppbv, 0.3-480 micrograms per cubic meter) and smoking (up to 600 ppbv, up to 253 micrograms per cubic meter).
Weak evidence.
Caveats
The cooking/smoking numbers are secondhand citations from other studies, not measurements from this paper, and the authors note their own small-surface controlled experiments likely understate real-world cleaning exposure (e.g., multiple surfaces cleaned in succession, as in the hotel).
Source: Souza 2025, ACS Earth Space Chem, ACS Earth and Space Chemistry Link to this fact
Health effects / Other evidence
At this Belgian center, cleaning-agent challenges were 3.2% of all work-asthma challenges in 1992-2001 and 8.6% in 2002-2011, and 16 of the 17 positive reactions came from the later decade.
Weak evidence: Share of referrals at one center, not incidence; referral patterns, awareness and QAC use may have changed. Authors call it only 'some suggestion' of an increase.
Health effects / Review of other studies
EWG said that about 53 percent of the cleaning products it assessed contain ingredients known to harm the lungs and about 22 percent contain chemicals reported to cause asthma to develop.
Weak evidence: Hazard flags from databases on an unspecified product set, not exposure or effect measures from product use; denominators and databases not named.
Source: EWG press release, Sept. 10, 2012, EWG press release (web page) Link to this fact
Health effects / Other evidence
In rodent studies of a hydrocarbon dry-cleaning solvent (Stoddard Solvent IIC), adrenal tumors appeared in male rats, liver adenomas in female mice were equivocal, and sperm motility fell at 550 milligrams per cubic meter in rats and 2200 in mice.
Weak evidence.
Caveats
Animal data for a related solvent with higher aromatic content (0.58-0.93%) than the 0.1% or less reported for the DC-142 product; the report uses it as a stand-in; current high-flash solvents are not directly tested.
Source: SCDHS 2018 Link to this fact
Health effects / Measured in people or real products
Only 2 of 69 irritant-induced asthma cases in a Finnish clinic series were cleaners; the authors suggest cleaning work involves long-term low-level irritant exposure that does not meet the criteria for irritant-induced asthma.
Weak evidence.
Caveats
Single-center retrospective case series; industrial workplaces, not households; no control group. The authors' interpretation, not tested; a clinic series cannot show how often cleaning products cause irritant asthma.
Source: Lindström 2021, Occupational and Environmental Medicine Link to this fact
Health effects / Other evidence
Studies in the panel's tables link accidental mixing of bleach with other cleaning products to higher asthma odds in cleaners: about 3.8 times in domestic cleaning women (95% CI 1.0-14) and 2.3 times in cleaning workers (95% CI 1.0-5.5).
Weak evidence: Small studies with very wide confidence intervals, self-reported incidents and recall bias; the paper notes reporting bias could not be excluded in the larger European cohort.
Hidden ingredients / Other evidence
Some cleaning makers disclosed nothing in 2012, while others used vague terms such as 'surfactant' and 'solvent' for ingredients.
Weak evidence: Qualitative statement by an advocacy group; no counts or product examples on this page.
Source: EWG press release, Sept. 10, 2012, EWG press release (web page) Link to this fact
Hidden ingredients / Measured in people or real products
In the same study, scented household cleaning products were not linked to higher levels of any measured chemical, and urine BPA was lower in children from homes that used them (ratio 0.69, 95% CI 0.49-0.98), so 'scented products' did not behave as one exposure.
Weak evidence: Likely chance or residual confounding on a wide multi-model estimate; shows heterogeneity of product categories rather than a protective effect.
Source: Fandiño-Del-Rio 2024, Journal of Exposure Science & Environmental Epidemiology Link to this fact
Indoor air / Review of other studies
During ordinary house cleaning with bleach, chlorine gas concentrations can peak at up to about 0.5 parts per million, and trichloramine is thought to reach similar concentrations when bleach reacts with ammonia or other nitrogen-containing substances.
Weak evidence: This is the authors citing a separate domestic-cleaner cohort study (their own ref. 15) as background, not a measurement made on the children or homes in this study.
Source: Nickmilder, Carbonnelle & Bernard 2007, Pediatric Allergy and Immunology Link to this fact
Indoor air / Other evidence
The authors judged that the PCE from dry-cleaned clothing is not itself a major health concern in Hong Kong because most households dry-clean rarely and ventilate, but high levels can occur in poorly ventilated homes with frequent dry cleaning.
Weak evidence.
Caveats
Authors' judgment from 3 rooms and a 500-household phone survey (64.6% dry-clean; 5% every 2-3 days, 34% every few months, 39% yearly); their own tables show some days above the CARB benchmark at all three sites.
Source: Chao 1998, Building and Environment Link to this fact
Indoor air / Other evidence
Wool dry cleaned repeatedly at the same shop kept absorbing more PCE with each cycle (about 47 nmol/cm2 after one cleaning to about 195 after six, read from Fig. 5), while cotton and polyester leveled off.
Weak evidence: One shop, one jacket, 1-6 cycles, replicate extractions not independent garments; values read from a chart.
Source: Sherlach 2011, Environmental Toxicology and Chemistry Link to this fact
Indoor air / Other evidence
OSHA says concentrations of many VOCs are consistently higher indoors, 'up to ten times higher', than outdoors, and lists cleaning supplies and pesticides among the thousands of product sources.
Weak evidence: A blanket multiplier with no data in the booklet; EPA pages say 2 to 5 times; primary data show compound-specific ratios from about 1 to about 60.
Source: OSHA 3430-04, 2011 Link to this fact
Indoor air / Other evidence
Someone doing their own house cleaning in a region with moderate outdoor ozone was estimated to inhale about 20 micrograms a day of formaldehyde and 35 micrograms a day of new particles from ozone reacting with cleaning-product and air-freshener ingredients.
Weak evidence.
Caveats
A modeled estimate borrowed from another review, not a measurement, for cleaning products and air fresheners together, not for perfume. It adds to formaldehyde and particles from other sources.
Source: Weschler 2006, Environmental Health Perspectives Link to this fact
Indoor air / Other evidence
Two products in the same category can behave very differently: with seed particles present, one deodorant turned about 17% of its evaporated mass into aerosol and the other about 6% (about, read from Fig. 2), and the two cleaning liquids ran about 5% and 12%.
Weak evidence: Approximate values read from Fig. 2; two products per category; the authors say the products are not representative of the market.
The industry / Other evidence
EWG linked companies' ingredient disclosure to 'pressure from customers and the threat of federal regulation', saying that is why most cleaning makers list at least some ingredients.
Weak evidence: EWG's explanation of company motives, not tested; no regulatory history is given.
Source: EWG press release, Sept. 10, 2012, EWG press release (web page) Link to this fact
The industry / Other evidence
EWG states it accepts no programmatic funding from food, household-cleaning, or personal-care companies, no funding for corporate-sponsored research, and no payment of any kind for inclusion or scoring in Skin Deep, Guide to Healthy Cleaning, or Food Scores.
Weak evidence: This is a policy statement by EWG itself; 'programmatic funding' is not defined and no audit of compliance is on the page.
Source: EWG Funding & Reports page, 2026, EWG website (web page) Link to this fact
Laws and loopholes / Government agency
No US program requires VOC emission testing of cleaning products: EPA Safer Choice certifies fragrance-free products but, per the authors, does not require or disclose emission testing, and the chamber data show hundreds of emitted chemicals missing from labels and industry databases.
Weak evidence.
Caveats
EWG-authored (advocacy nonprofit that ranks cleaners and licenses EWG VERIFIED to cleaner makers); Skyline Foundation grant; unblinded; The authors' characterization of Safer Choice (2016 reference); not independently checked against current program rules.
Laws and loopholes / Other evidence
EWG calls the lack of public safety information on chemicals in everyday products 'a major failing of the nation's outdated chemical policy' and says manufacturers and government 'largely leave consumers in the dark' about cleaning-product contents.
Weak evidence: Advocacy-organization position in 2012, with no data or citation in this piece.
Source: Andrews, EWG, 2012 (web page) Link to this fact
Skin allergy / Other evidence
Scented laundry and cleaning products (hair-styling products, laundry detergent, fabric softener, usually floral-scented) formed one group of odors migraine patients named, and chronic migraine patients named this group more often than episodic patients (P = 0.037).
Weak evidence.
Caveats
Only 16 chronic patients, no correction for multiple tests, and the paper's own percentages do not reconcile; cross-sectional, so it cannot show that chronic migraine increases sensitivity.
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 / Government agency
As of 1998, EPA planned to expand its voluntary consumer-labeling initiative beyond pesticides to labels on household and other consumer products such as cleaning agents and latex paint, aiming to give clearer hazard information, especially for children.
Weak evidence.
Caveats
A stated 1998 plan/intention, not a completed program; the paper does not report whether or how it was implemented, and no fragrance-specific labeling requirement is described anywhere in the paper.
Source: Goldman 1998, Environmental Health Perspectives Link to this fact
What you can do / Measured in people or real products
Running an ozone-generating device (an ionizer, or some 'air purifiers') at the same time as using citrus- or terpene-scented cleaning or personal-care products creates the same class of reaction-product nanoparticles studied here; keeping the two apart in time, or ventilating, avoids generating them.
Weak evidence.
Caveats
This study alone did not find a significant health effect from the terpene+ozone arm; the precautionary action is supported by the wider ozonolysis-SOA literature in our evidence base (see transformation-products), not by this study's HRV result in isolation. Downgraded to weak 2026-09-28 (Jev audit): the action goes beyond what this paper itself tested.
Source: Hagerman et al. 2014, Atmospheric Environment Link to this fact
What you can do / Measured in people or real products
Regularly cleaning a dryer's lint trap and keeping vent ducting short and well-maintained is associated with differences in how much microfiber reaches the outside vent, based on comparing two homes with different dryer ages and duct setups.
Weak evidence.
Caveats
This is a two-home comparison, not a tested intervention — the study did not clean or modify ducting and measure a before/after change, so this is an inference from correlation, not a demonstrated fix.
Source: Kapp & Miller 2020, PLOS ONE Industry-funded Link to this fact
What you can do / Other evidence
A structured home walkthrough that identifies and removes common VOC sources (mothballs, scented cleaning and personal-care products, candles, garage-stored chemicals) and separates stored chemicals from living space (e.g., moving gasoline/solvents/paints to detached storage) reduced measured indoor VOC levels in the homes studied.
Weak evidence.
Caveats
Professional testing and a trained team delivered this intervention over 5 visits across a year; the paper does not test which individual component (removal vs. substitution vs. new storage vs. counseling) drove the VOC reduction. Evidence is one small uncontrolled case series.
Source: Rincón et al. 2024, Primary Health Care Research & Development Link to this fact
What you can do / Self-reported survey
Migraineurs who notice their attacks are triggered by specific odors (most commonly perfume, cleaning products, cigarette smoke, or vehicle exhaust in this sample) may reasonably consider reducing exposure to those specific triggers as a low-cost self-management step.
Weak evidence: Based on self-reported association in one clinical sample, not a controlled-avoidance or provocation trial; benefit of avoidance was not tested.
Source: Fornazieri 2016, Headache: The Journal of Head and Face Pain Link to this fact
What you can do / Other evidence
Salon-side measures the authors recommend to cut hairdressers' hair-dye skin exposure: single-use disposable gloves put on before mixing the dye, cutting hair before dyeing rather than after, changing work-surface coverings, and cleaning phones, hair dryers, scissors, and combs often.
Weak evidence: Recommendations are the authors' judgment; the study did not test whether these changes lower exposure.
Source: Lind et al. 2005, The Annals of Occupational Hygiene Link to this fact
What you can do / Review of other studies
Professional wet cleaning (water-based, computer-controlled machines, mild biodegradable detergents) was rated the lowest-risk way to clean clothes in a 2016 review; in a California demonstration, seven shops that switched from perc kept 97% of customers with similar problem-garment rates.
Weak evidence.
Caveats
Secondary review funded by Australian Wool Innovation (wool industry body); 'systematic' is a self-label with no study counts or appraisal; relies on agency, trade and manufacturer sources. The 'no identified health hazards' judgment rests on the 2000 California demonstration and agency/trade sources; the review itself found no later comparison studies, no measurements of residues of any non-perc cleaning agent, and says wet cleaning cannot handle every garment.
Source: Troynikov 2016, Journal of Environmental Management Industry-funded Link to this fact
What you can do / Other evidence
EWG's method scores cleaning products from publicly available information (the label, the manufacturer's website, and safety data sheets), so an unlisted ingredient such as a fragrance constituent cannot lower a grade.
Weak evidence: Inference, not a statement in the page. Fragrance is never mentioned; the claim holds only for what is absent from all three sources.
Source: Andrews, EWG, 2012 (web page) Link to this fact
Information, not medical advice. See also: myths we won’t tell you.