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.
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
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 / 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 / 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
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 / Other evidence
Treat a strong, persistent solvent-type smell (heavy cleaning, fresh paint, new furnishings in a poorly ventilated space) as a plausible trigger for eye, nose, throat, or mild respiratory irritation, and ventilate or leave the area if symptoms appear.
Moderate evidence: The doses tested were far higher than most ventilated homes reach; this advice is about avoiding irritant symptoms, not about a demonstrated injury risk from ordinary indoor air.
Source: Pappas et al. 2000, Int J Occup Environ Health 6:1-8 Link to this fact
What you can do / Review of other studies
Never mix chlorine bleach with ammonia or acidic cleaning products, since this releases chlorine gas or trichloramine, both strong respiratory and eye irritants documented to cause acute lung injury in cleaners and housewives.
Moderate evidence: Drawn from background literature the authors cite (occupational case reports and reviews), not from new data collected in this study.
Source: Nickmilder, Carbonnelle & Bernard 2007, Pediatric Allergy and Immunology Link to this fact
What you can do / Review of other studies
When relying on a workplace, clinic, or school's fragrance-free policy, check whether it (1) defines what's covered beyond perfume, especially cleaning and laundry products, (2) sets a default fragrance-free expectation rather than a complaint-triggered one, (3) controls what cleaning/laundry products the institution buys, and (4) names a real consequence for non-compliance — a 2026 scoping review of 63 such policies found these structural features present in well under half of cases.
Moderate evidence: Based on a gray-literature document review of North American policies; individual policies may vary, and having these features on paper does not guarantee enforcement.
What you can do / Government agency
A resident of HUD-assisted housing with a documented chemical sensitivity can cite this HUD exhibit directly when requesting advance notice before common-area cleaning and nonchemical cleaning products where practical, since HUD's own guidance names these as accommodations that are not an undue burden.
Moderate evidence.
Caveats
Applies specifically to HUD-assisted (Section 504-covered) multifamily housing; the same specific accommodations are not guaranteed at privately owned housing covered only by the Fair Housing Act, where the undue-burden analysis is done case by case.
Source: HUD Occupancy Handbook 4350.3 REV-1, Exhibit 2-6 (2007) Link to this fact
What you can do / Other evidence
Hairdressers, salon workers, and professional or domestic cleaners can reduce workplace asthma risk with ventilation, gloves, and lower-irritancy products or application methods where available, since this population-based cohort found both hairdressing and cleaning occupations, and reactive cleaning/disinfecting chemical exposure specifically, associated with higher adult-asthma risk.
Moderate evidence.
Caveats
The study cannot identify which specific chemicals within 'hairdressing' or 'cleaning/disinfecting' exposure are responsible, so this is general occupational-hygiene advice, not a product-specific recommendation.
What you can do / Other evidence
Ventilating a bathroom or other small room during and right after cleaning (opening a window, running an exhaust fan) is likely to cut both the particle and VOC bump from cleaning, since the single biggest difference between a low-impact room and a high-impact room in this study was air change rate, not which cleaner was used.
Moderate evidence: Based on one study's four rooms, not a controlled ventilation experiment within one room; advice is directionally supported, not quantified for a specific home.
Source: Souza 2025, ACS Earth Space Chem, ACS Earth and Space Chemistry Link to this fact
What you can do / Other evidence
When only cleaning (not disinfecting a specific pathogen), wiping up a quats disinfectant promptly rather than letting it sit for several minutes keeps both PM2.5 and TVOC much lower; leaving it the full label-specified 10-minute disinfection dwell time in a bathroom raised PM2.5 by 68% and TVOC about 8-fold compared with a 2-3 minute wipe-off.
Moderate evidence.
Caveats
Single bathroom, small N (1-5 per condition); a shorter dwell time may not achieve the disinfection the label is written for, so this is a cleaning-vs-disinfecting tradeoff, not a free upgrade.
Source: Souza 2025, ACS Earth Space Chem, ACS Earth and Space Chemistry Link to this fact
What you can do / Review of other studies
Most dry-cleaning alternatives to perc are not proven safer: a 2016 review found the long-term health effects of hydrocarbon solvents 'not well understood', flagged siloxane D5 (GreenEarth) as bioaccumulative, and listed chronic effects for hydrocarbons and liquid CO2 as 'unknown'.
Moderate 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. 'Unknown' means not studied, not shown harmful; much of the hazard data comes from agency and manufacturer documents.
Source: Troynikov 2016, Journal of Environmental Management Industry-funded Link to this fact
What you can do / Other evidence
EWG Verified bans quaternary ammonium compounds, formaldehyde releasers, isothiazolinones, phthalates, PFAS, boron compounds, and nitro- and polycyclic musks (galaxolide) in licensed cleaners.
Moderate evidence: EWG's own list drawn from other bodies' hazard lists; it shows what the label excludes, not that the remaining ingredients are harmless.
Source: EWG Verified criteria for cleaning products (10.24), Environmental Working Group, 2024 Link to this fact
What you can do / Other evidence
OSHA recommends scheduling cleaning or maintenance work when other occupants are absent and limiting the amount and location of chemicals used near workers.
Moderate evidence: Advisory administrative controls; no evidence of effectiveness given.
Source: OSHA 3430-04, 2011 Link to this fact
Information, not medical advice. See also: myths we won’t tell you.