At a glance
| Chemical family | Triatomic oxygen — reactive oxidant gas (environmental, not a manufactured chemical) |
| CAS number | 10028-15-6 |
| Classification | Not individually IARC classified. EPA criteria air pollutant with NAAQS standard (70 ppb, 8-hr average). WHO air quality guideline: 100 ug/m3 (8-hr average). Respiratory irritant. Driver of secondary indoor pollutant formation |
| Where you encounter it | Outdoor air (photochemical smog); infiltrates indoors through windows and ventilation; indoor sources include ionic air purifiers, UV germicidal devices, laser printers, and some electrostatic precipitators |
| Sleep micro-environment relevance | Drives secondary chemistry during sleep: reacts with skin oils to produce aldehydes in the breathing zone; reacts with terpenes to produce ultrafine particles; reacts with surfaces to produce formaldehyde. Indoor ozone is the hidden variable in bedroom air quality |
Regulatory & certification status
| European Union | Ambient Air Quality Directive (2008/50/EC) sets a target value for ozone of 120 ug/m3 (8-hr average). No indoor air quality directive for ozone. Regulatory |
| United States | EPA NAAQS: 70 ppb (0.070 ppm, 8-hour average). Clean Air Act criteria pollutant. FDA limits ozone output from indoor air purifiers to 50 ppb. California Air Resources Board (CARB) regulates ozone from air cleaners. Regulatory |
| Canada | Canadian Ambient Air Quality Standards (CAAQS) for ozone. No indoor-specific ozone standard. Health Canada's Residential Indoor Air Quality Guidelines address ozone-generating air cleaners. Regulatory |
| International | WHO Air Quality Guidelines: 100 ug/m3 (8-hr average). EPA NAAQS: 70 ppb. Not individually IARC classified. Recognised as a driver of secondary indoor chemistry by the indoor air quality research community. Regulatory |
What it is
Ozone is a triatomic form of oxygen (O3) that is a powerful oxidant. In the outdoor atmosphere, ground-level ozone forms through photochemical reactions between nitrogen oxides (NOx) and volatile organic compounds in sunlight. Ozone infiltrates indoors through windows, doors, and ventilation systems. Indoor ozone concentrations are typically 20-70% of outdoor levels, depending on the building's air exchange rate and the presence of indoor surfaces that consume ozone. IARC has not evaluated ozone in an individual monograph. The EPA regulates ozone as a criteria air pollutant under the Clean Air Act — the current NAAQS is 70 ppb (8-hour average). The WHO air quality guideline is 100 ug/m3 (8-hour average). Ozone's significance for bedroom air quality is not its direct respiratory irritant effect (which is well-known) but its role as a driver of secondary indoor chemistry.
Where it shows up in bedding
Ozone in the bedroom reacts with the human occupant and with bedroom materials in several important ways. First, ozone reacts with squalene and unsaturated fatty acids on the skin surface to produce a suite of aldehydes — primarily 6-MHO (6-methyl-5-hepten-2-one), 4-OPA (4-oxopentanal), nonanal, decanal, and octanal — directly in the breathing zone during sleep. Second, ozone reacts with terpenes (limonene, alpha-pinene) from scented laundry products, air fresheners, and cleaning agents to produce ultrafine particles and secondary organic aerosol — ironically, products designed to make bedding smell fresh can produce respiratory irritants when ozone is present. Third, ozone reacts with surfaces (carpet, bedding, furniture) to produce formaldehyde and other oxidation products. Keeping windows closed during high-ozone periods and avoiding ozone-generating air purifiers reduces these reactions.
Citations
- Weschler, C.J. (2006). Ozone's Impact on Public Health: Contributions from Indoor Exposures to Ozone and Products of Ozone-Initiated Chemistry. Environmental Health Perspectives, 114(10): 1489-1496. Source Peer-reviewed
- Wisthaler, A. and Weschler, C.J. (2010). Reactions of Ozone with Human Skin Lipids. Proceedings of the National Academy of Sciences, 107(15): 6568-6575. Source Peer-reviewed
- EPA. Ground-level Ozone — National Ambient Air Quality Standards (NAAQS). Source Regulatory
Frequently asked questions
Should I use an air purifier that produces ozone?
No. Ozone-generating air purifiers (ionic air purifiers, electrostatic precipitators, and UV-based devices that produce ozone as a by-product) add ozone to indoor air, which drives the formation of secondary pollutants — aldehydes from skin oil oxidation, ultrafine particles from terpene reactions, and formaldehyde from surface reactions. HEPA air purifiers and activated carbon filters clean indoor air without producing ozone. The California Air Resources Board and the FDA both limit ozone emission from air-cleaning devices.
Does ozone react with my skin while I sleep?
Yes. Indoor ozone continuously reacts with squalene and unsaturated fatty acids on the skin surface. This produces a suite of oxygenated products — aldehydes like 6-MHO, 4-OPA, nonanal, and decanal — directly in the breathing zone. The reaction rate depends on indoor ozone concentration, skin surface area exposed, and skin lipid composition. This has been demonstrated in chamber studies and contributes measurably to the VOC profile of occupied bedrooms.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-07-08. If you find a factual error, contact us.