At a glance
| Chemical family | A straight-chain (C₉) aliphatic aldehyde — perfumery's Aldehyde C-9 |
| CAS number | 124-19-6 |
| Classification | Not classified as a carcinogen; a low-toxicity, permitted flavouring substance. Its indoor relevance is as a potent odorant and mild irritant |
| Where you encounter it | Off-gassing from wood panels, sealants, vinyl and foam; formed from cooking-oil oxidation and vehicle interiors; generated when indoor ozone reacts with skin and surface lipids; natural in citrus and many foods |
| Sleep micro-environment relevance | One of the most common indoor aldehydes; detectable by smell well below any toxic level, so it dominates "new" odours without dominating exposure risk |
| Activated carbon capture | Well-adsorbed; ventilation and airing of new materials handle most of it |
Regulatory & certification status
Where Nonanal stands across the major regulatory systems and the certifications a bedroom product might carry. Each row links to the governing instrument; where a jurisdiction has no specific measure, that is stated plainly rather than left blank.
| European Union | Nonanal (EC 204-688-5, CAS 124-19-6) is registered under EU REACH. It is not on the SVHC Candidate List, not on the Authorisation List (Annex XIV), and no Annex XVII restriction targeting it was identified. No harmonised CLP classification (Annex VI of Regulation (EC) No 1272/2008) was identified, so any hazard labelling would rest on supplier self-classification. ECHA infocards are bot-blocked, so this reflects the registration record and the absence of the substance from the candidate/authorisation/restriction lists rather than a direct read of the ECHA infocard. Regulatory — ECHA |
| United States | Nonanal is on the EPA TSCA inventory and no TSCA risk evaluation or regulatory action against it was identified. It is not listed on California's Proposition 65 — independently verified by searching the full OEHHA Proposition 65 list (no entry for nonanal or for CAS 124-19-6, and no cancer, developmental, or reproductive-toxicity listing). Regulatory — OEHHA |
| Canada | Nonanal was assessed under the CEPA Chemicals Management Plan as one of five substances in the Aldehydes Group (with benzaldehyde, octanal, methylbenzaldehyde and vanilla oils). The final assessment, published in the Canada Gazette, Part I on 25 May 2024, concluded that these substances do not meet any of the criteria set out in section 64 of CEPA, and the Ministers gave notice that they propose to take no further action on them under section 77 of the Act. Nonanal is not added to Schedule 1 (List of Toxic Substances). Regulatory — Government of Canada · Canada Gazette |
| Australia | Nonanal appears to be a listed industrial chemical eligible for industrial use in Australia under the scheme administered by AICIS, and no specific AICIS/IChEMS risk restriction or scheduling decision targeting nonanal was identified. The Australian Inventory of Industrial Chemicals is searched through an interactive AICIS portal, so the specific inventory listing could not be independently confirmed from a static primary source here. Regulatory — AICIS |
| United Kingdom | Following EU exit, nonanal falls under UK REACH and GB CLP administered by HSE. No entry for nonanal on the GB Mandatory Classification and Labelling (GB MCL) list was identified, which would be consistent with Great Britain carrying over the inherited EU baseline of no harmonised classification (self-classification applies). This reflects a no-entry-found result rather than an independently confirmed GB-specific decision. Regulatory — HSE |
| Certifications | Treatment differs by program. The CertiPUR-US technical guidelines do not name nonanal (no occurrence of nonanal or CAS 124-19-6 in the 2025 Slabstock guidelines); the program screens for CMR-classified chemicals and applies a total-VOC ceiling (<0.5 ppm) plus a formaldehyde limit, so nonanal would only be captured indirectly within the TVOC figure. GREENGUARD/GREENGUARD Gold, which uses the California CDPH Standard Method, does name nonanal: its emissions criteria require the sum of normal aldehydes 'from formaldehyde through nonanal, plus benzaldehyde' to be individually calibrated and reported, so nonanal is a measured target aldehyde rather than a stand-alone limit. Nonanal is not among the individually limited CDPH CREL target VOCs. OEKO-TEX Standard 100 sets textile VOC/odour-related limits but no dedicated nonanal limit was identified. Industry — CertiPUR-US · UL GREENGUARD |
| The 72-hour test window | Readily detected. Nonanal is a volatile C9 aldehyde and a common chamber-emission odorant, so it off-gasses into air and a short (~72 h) VOC emissions test captures it well. Inferred — from the compound's volatility/emission profile versus the VOC focus of short chamber tests |
What it is
Nonanal is a simple straight-chain aldehyde, nine carbons long, with a characteristic fatty, waxy, citrus odour. It is a workhorse of flavour and fragrance — known in perfumery as Aldehyde C-9 — occurs naturally in citrus peel and more than two hundred foods, and is used as a permitted flavouring at the level of a few parts per million. Industry — The Good Scents Company In other words, it is a low-toxicity molecule you have eaten and smelled countless times; its interest here is not poison but ubiquity.
What makes nonanal matter indoors is that the same fatty-acid chemistry that puts it in citrus also produces it from oxidising materials. Straight-chain aldehydes such as hexanal, octanal and nonanal are routinely detected in indoor air as the fatty acids in wood, foams and oils slowly oxidise. Peer-reviewed — Maddalena et al. 2009, Environ. Sci. Technol.
How it relates to the bedroom
The smell of "new"
A great deal of "new furniture," "new car," and "new mattress" smell is aldehydes, and nonanal is one of the most recognisable. A 2009 study of temporary housing units measured emissions from their materials and found that nonanal was one of just two compounds — alongside formaldehyde — whose modelled indoor concentrations exceeded chronic reference exposure levels or odour thresholds, traced to composite wood, sealants and vinyl coverings. Peer-reviewed — Maddalena et al. 2009 For nonanal, whose odour threshold is very low, the most plausible reading of that result is that you smell it long before it reaches a toxic level. Inferred — nonanal's low odour threshold means threshold exceedance most likely reflects odour
Made in your breathing zone
Nonanal also has a second, more intimate source. When indoor ozone reaches the thin film of oil on your skin — and on the surfaces around you — it reacts with squalene and unsaturated fatty acids to generate a family of aldehydes and carbonyls right in your breathing zone. Peer-reviewed — Wisthaler & Weschler 2010, PNAS Nonanal is among the aldehydes this skin-ozone chemistry can yield, though it is harder to pin down individually than markers like 6-MHO because of measurement overlap. Inferred — nonanal's specific skin-ozone yield is not cleanly resolved in the source measurements The same study noted that some of these skin-ozone products can act as respiratory or skin irritants. Peer-reviewed — Wisthaler & Weschler 2010
Smell as a signal, not a verdict
Nonanal is the clearest case in the Atlas of a compound whose importance is sensory. Because the nose registers it at a tiny fraction of any toxic concentration, a strong fatty-citrus "new" smell is best read as a cue that a room needs airing, not as evidence of a dangerous exposure. Inferred — odour detection far below toxicological thresholds That is a useful reframing: ventilation answers the smell and the (small) exposure at the same time.
What the research says
- It is a ubiquitous material-emitted indoor aldehyde. From wood panels, sealants, vinyl and foam; flagged with formaldehyde for exceeding reference levels or odour thresholds. Peer-reviewed — Maddalena et al. 2009
- It also forms from skin–ozone chemistry. Ozone plus skin lipids yields aldehydes and carbonyls, some irritant. Peer-reviewed — Wisthaler & Weschler 2010
- It is a low-toxicity, permitted flavouring. Naturally in citrus and many foods; used in flavours at low ppm. Industry — flavour/fragrance documentation
- Its dominant indoor role is odour. Detectable far below any toxic level. Inferred
What helps reduce it
Ventilate. Fresh-air exchange is the main control — it clears nonanal along with the rest of the new-material and new-foam emissions.
Air out new furnishings and foam. Unwrapping and ventilating new wood furniture, mattresses and foam in a well-aired space speeds the fade of the aldehyde smell.
Don't add ozone. Avoid ozone-generating "air purifiers" — ozone reacting with skin and surface lipids is one of the ways nonanal and related aldehydes are produced indoors. Peer-reviewed — Wisthaler & Weschler 2010
What does NOT help
- Treating the smell as a measure of danger. Nonanal is detectable far below any toxic level; the odour is a prompt to ventilate, not evidence of harm. Inferred
- Masking it with fragrance. Adding scented product layers more reactive VOCs into the room without removing the aldehyde. Inferred
Open research questions
- Nonanal's specific contribution to the skin-ozone aldehyde burden in the bedroom, given the measurement overlap that complicates its identification. Speculation
- The health relevance, if any, of chronic low-level exposure to mixtures of straight-chain aldehydes indoors. Speculation
The Embr Exposure Ledger: Nonanal (Aldehyde C-9)
One chemical, several public questions, answered from independent datasets and joined here — the environment it shows up in, the body burden it carries, how it is regulated, and what actually reduces it.
Detection and body-burden figures are occurrence data, not a personal measurement or a health diagnosis. Part of the Embr Exposure Ledger — an open, cross-dataset chemical join (download the data), reusable with attribution.
Citations
- Maddalena R, Russell M, Sullivan DP, Apte MG (2009). Formaldehyde and other volatile organic chemical emissions in four FEMA temporary housing units. Environmental Science & Technology, 43(15):5626–5632. DOI 10.1021/es9011178 (PMID 19731654). Via PubMed. Peer-reviewed
- Wisthaler A, Weschler CJ (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. DOI 10.1073/pnas.0904498106 (PMID 19706436). Via PubMed. Peer-reviewed
- The Good Scents Company. Nonanal (Aldehyde C-9), CAS 124-19-6 — flavour and fragrance identity: a fatty, citrus aldehydic odorant naturally present in citrus and many foods, used as a permitted flavouring at low ppm. thegoodscentscompany.com Industry
Frequently asked questions
What is that "new furniture" or "new car" smell, and is nonanal part of it?
Straight-chain aldehydes like hexanal, octanal and nonanal are a big part of it. Nonanal in particular has a strong fatty, citrus-like odour and is released from composite wood (particleboard and MDF), sealants, vinyl, and foam as the fatty acids in those materials slowly oxidise. Because the human nose detects nonanal at very low concentrations, it contributes to the "new" smell well before it reaches any level of toxicological concern.
Is nonanal harmful?
Nonanal is low in toxicity. It is a permitted flavouring substance, occurs naturally in citrus and over 200 foods, and is used in flavours at a few parts per million. Its relevance indoors is mostly as an odorant and mild irritant rather than a systemic-toxicity or cancer concern. In one housing-unit study, nonanal was flagged alongside formaldehyde as exceeding chronic reference levels or odour thresholds — for nonanal, with its very low odour threshold, that most plausibly reflects smell rather than a toxic dose.
Where does the nonanal in my bedroom come from?
Several places at once: it off-gasses from wood-based panels, sealants, vinyl and foam as their fatty-acid content oxidises; it forms from cooking-oil oxidation and is emitted by vehicle interiors; and it is generated in your breathing zone when indoor ozone reacts with the lipids on your skin and on surfaces. It is one of the most ubiquitous aldehydes in indoor air.
How do I reduce nonanal?
Ventilation is the main lever: fresh-air exchange clears nonanal along with the rest of the new-material and new-foam emissions, and airing out new furniture or a new mattress in a well-ventilated space speeds the fade. Avoiding ozone-generating devices also helps, because ozone reacting with skin and surface lipids is one of the ways nonanal and related aldehydes are formed indoors.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-06-27. If you find a factual error, contact us.