Skin chemistry — occupant emission

Decanal in the bedroom

By — 19-year firefighter and entrepreneur. Published July 2026.

Decanal is a ten-carbon aldehyde produced when ozone reacts with squalene — the major unsaturated lipid on human skin. IARC has not classified decanal for carcinogenicity. Decanal is one of several aldehydes (along with 6-methyl-5-hepten-2-one, or 6-MHO, and 4-oxopentanal, or 4-OPA) that serve as chemical markers of occupied indoor spaces. Concentrations of decanal rise when a room is occupied and are elevated during sleep, when a person's body surface is in sustained contact with bedding in a closed room. Decanal is a product of human body chemistry interacting with the indoor environment.

Decanal — Embr Bedroom Chemistry Atlas

At a glance

Chemical familyAliphatic aldehyde — C10 saturated aldehyde (occupant emission from squalene-ozone reaction)
CAS number112-31-2
ClassificationNot IARC classified. Not a regulated pollutant. A natural product of skin-ozone chemistry. FDA GRAS as a food flavouring agent. Mild irritant at high concentrations
Where you encounter itIndoor air (elevated in occupied rooms); produced on human skin by ozone-squalene reaction; also emitted from some citrus fragrances and cleaning products; food flavouring agent
Sleep micro-environment relevanceConcentrations rise during sleep as body surface interacts with indoor ozone on bedding. A chemical signature of the occupied bedroom. Part of the understudied sleeper emission chemistry

Regulatory & certification status

European UnionREACH registered. CLP Skin Irrit. 2, Eye Irrit. 2. No indoor air quality limit. Not a regulated pollutant. Regulatory
United StatesFDA GRAS flavouring agent. No EPA air standard. No OSHA PEL. Studied as an occupant emission marker in indoor air quality research. Regulatory
CanadaNo indoor air quality guideline for decanal. Included in Health Canada occupant emission research. Regulatory
InternationalNot IARC classified. No WHO guideline. Studied as part of the emerging field of human chemical emission and indoor chemistry. Regulatory

What it is

Decanal (n-decanal, capric aldehyde) is a straight-chain C10 aldehyde with a waxy, orange-peel odour. In the context of indoor air chemistry, decanal is primarily produced by the reaction of ozone with squalene — a C30 unsaturated hydrocarbon that is the most abundant lipid on the human skin surface, comprising approximately 12% of skin surface lipids. When indoor ozone contacts skin, it cleaves squalene's double bonds through ozonolysis, producing a characteristic suite of aldehydes and ketones: 6-MHO, 4-OPA, acetone, geranyl acetone, and decanal. This skin-ozone chemistry occurs continuously whenever a person is present in a room with measurable ozone. IARC has not evaluated decanal. It is approved as a GRAS food flavouring agent and is naturally present in citrus oils.

Where it shows up in bedding

Decanal production in the bedroom is uniquely tied to the sleeper's presence. During sleep, the large body surface area in contact with bedding and exposed to room air provides a continuous reaction surface for ozone-squalene chemistry. Bedroom ozone concentrations are typically lower at night (less outdoor infiltration, no UV), but any ozone present reacts with skin lipids on the sleeper and on lipid residues deposited on bedding surfaces. Decanal concentrations in bedroom air are elevated during occupied sleep periods compared to when the room is empty. The health significance of decanal at these concentrations is minimal — they are well below irritation thresholds. Decanal is of scientific interest because it demonstrates that the sleeper is not a passive occupant but an active chemical emitter who changes bedroom air composition.

Citations

  1. Weschler, C.J. et al. (2007). Ozone-Initiated Chemistry in an Occupied Simulated Aircraft Cabin. Environmental Science & Technology, 41(17): 6177-6184. Source Peer-reviewed
  2. Wisthaler, A. and Weschler, C.J. (2010). Reactions of ozone with human skin lipids: Sources of carbonyls, dicarbonyls, and hydroxycarbonyls in indoor air. Proceedings of the National Academy of Sciences, 107(15): 6568-6575. Source Peer-reviewed
  3. WHO (2010). WHO Guidelines for Indoor Air Quality: Selected Pollutants. Source Regulatory

Frequently asked questions

  • Is decanal harmful?

    At the concentrations produced by skin-ozone chemistry in a bedroom, decanal is not harmful. It is a natural product of human body chemistry, present in food and fragrances, and approved as a GRAS flavouring agent. Indoor concentrations from occupant emissions are well below irritation thresholds.

  • Why is decanal scientifically interesting for sleep?

    Decanal is part of the emerging science of human chemical emissions — the 'chemical cloud' that every person generates. During sleep, the sustained exposure of body surface to indoor air in a closed room creates a measurable chemical signature. Understanding this chemistry is relevant to ventilation requirements, air quality standards for bedrooms, and the interaction between human emissions and other indoor pollutants.

Related compounds

  • Hexanal — another indoor aldehyde (from material emissions)
  • Formaldehyde — the most regulated indoor aldehyde
  • Acetaldehyde — another common indoor air aldehyde
  • Limonene — a terpene whose ozone reaction products include aldehydes

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.