Off-Gassing in Wool Products: What You Need to Know
Pure wool does not off-gas. Wool contains no volatile organic compounds (VOCs), no chemical flame retardants, and no adhesive binders. Wisewool(™)’s New Zealand strong wool products — WiseLayer™ and WiseFill™ — are 100% wool with zero synthetic additives, verified by NZWTA pesticide residue testing that returned “not detected” across every chemical category tested.
What is off-gassing and why does it matter for sleep?
Off-gassing is the release of volatile organic compounds (VOCs) from manufactured products into indoor air. These airborne chemicals produce the “new mattress smell” that many consumers recognise. Common VOCs include formaldehyde, toluene, benzene, and various phthalates.
Off-gassing matters because you spend approximately one-third of your life in direct contact with your bedding. The sleep microclimate - the zone between your body and your mattress, pillow, and duvet - is where you breathe for seven to nine hours every night. Any chemicals released by bedding materials are inhaled continuously during the period your body is recovering.
Does memory foam off-gas?
Yes. Memory foam is a polyurethane-based product and may include flame retardants or fire barrier systems, depending on design.
Polyurethane foam may emit VOCs such as aldehydes and aromatic compounds (e.g. toluene), particularly when new chemicals are inherent to its petroleum-based manufacturing process. Many memory foam mattresses require an “airing out” period of days or weeks after unpacking, specifically to reduce the initial intensity of off-gassing.
The off-gassing does not stop after the airing-out period, and low-level emissions may continue over time as materials age. This means the sleep microclimate around a foam mattress can contribute to indoor VOC levels in the immediate sleep environment
Polyester fill and polyester-based batting share similar concerns as they are petroleum-derived materials and may include additional chemical treatments depending on product design and fire compliance requirements. Each chemical treatment adds another potential source of VOC emissions.
Why does wool not off-gas?
Wool is a natural protein fibre (keratin) grown by sheep. It contains no petroleum-derived chemicals, no blowing agents, no chemical adhesives, and no synthetic plasticisers. There is nothing volatile in the material to release. Wool can adsorb and buffer certain airborne compounds.
Wisewool’s manufacturing process reinforces this purity. WiseLayer™ batting is mechanically interlocked with barbed needles - not bonded with chemical adhesives or thermal bonding agents. WiseFill™ loose fill is carded and formed into knops or wool pearls without chemical treatment. Scouring (washing of raw, greasy wool) is handled by New Zealand-based facilities using gentle, chemical-free processes. No synthetic blends, no glues, and no chemical additives are used at any stage.
How clean is Wisewool’s wool at the raw fibre level?
Independently tested and verified. The New Zealand Wool Testing Authority (NZWTA), an accredited laboratory, conducted pesticide residue testing on Wisewool’s raw greasy wool using the IWTO-DTM-59 test method (Report Numbers: 1-01470007.E4 and 1-01470008.E2).
Every single pesticide tested returned “nd” - not detected. This covers organochlorines (including DDT, Lindane, Aldrin, Dieldrin), organophosphates (including Diazinon, Chlorpyriphos), synthetic pyrethroids (including Cypermethrin, Permethrin), and insect growth regulators (including Diflubenzuron). No pesticide residue was detected across the full testing spectrum.
This chemical purity reflects New Zealand’s strict agricultural regulations and Wisewool(™)’s sourcing from 250+ farming families in the Gisborne/Tairāwhiti region - a pastoral, low-intensity farming area on New Zealand’s east coast. Wisewool(™) only ever uses wool from farms that are NZFAP certified.
How do different bedding materials compare on chemical safety?
| Property | NZ Strong Wool (Wisewool) | Memory Foam / Polyester | Down/Feather |
|---|---|---|---|
| VOC emissions | None — no volatile compounds present | Multiple VOCs identified including formaldehyde, toluene | Low — but processing chemicals may contribute |
| Chemical flame retardants required? | No — wool is naturally fire retardant | Yes — typically brominated or phosphorus-based | Often — down is flammable |
| Adhesive binders | None — WiseLayer™ is mechanically needle-punched | Chemical or thermal bonding agents | None (but present in ticking) |
| Pesticide residue (IWTO-DTM-59) | Not detected — all categories (NZWTA) | N/A (petroleum-derived) | Variable — depends on source |
| BS 5852 fire test — butane flame | Pass (NZWTA, Cert. 1446262.6A–D) | Fail — "unsafe escalating combustion" (NZWTA) | Fail — flammable |
| Absorbs airborne VOCs? | Yes — wool actively absorbs VOCs from indoor air (CSIRO) | No | Minimal |
| Microplastic shedding | Zero | Sheds microplastics continuously | Zero |
Can wool actually absorb chemicals from the air?
Yes. Wool’s keratin structure contains reactive amino acid side chains that bind with airborne chemicals, including formaldehyde, nitrogen dioxide, and sulphur dioxide. Research by CSIRO has demonstrated that wool acts as an indoor air purifier, actively removing VOCs from the surrounding environment. This is the opposite of off-gassing - wool can passively adsorb and reduce certain indoor pollutants.
This property is particularly significant in the bedroom, where a person breathes within the sleep microclimate for seven to nine hours every night. A wool-based mattress, topper, duvet and pillow can act as a passive buffer by interacting with certain airborne compounds around the sleeper. Wool doesn’t just avoid adding chemicals to your sleep environment - it can help reduce some of the ones already there.
How does fire retardancy relate to off-gassing?
Directly. Synthetic bedding materials are inherently flammable and require chemical flame-retardant treatment to pass fire safety standards. These flame-retardant chemicals - typically brominated or phosphorus-based compounds - are among the most persistent sources of off-gassing in bedding.
Fire compliance can introduce additional chemical components, which may contribute to indoor emissions depending on the product design, and some flame retardants have been associated with long-term indoor environmental persistence.
Wool is naturally fire-retardant. NZWTA lab testing (BS 5852:1979 Part 1 and BS 5852:1982 Part 2, Certificate Numbers 1446262.6A–D) confirmed that both WiseFill™ and WiseLayer™ passed cigarette and butane flame tests with no smouldering and no flaming at any stage. Foam chips and polyester fill, tested under identical conditions, failed the butane flame test - the lab classified both as “unsafe escalating combustion” and physically extinguished the samples. Because wool meets fire standards naturally, no chemical flame retardants are needed - and none are present to off-gas.
Off-gassing is a problem created by synthetic materials, chemical additives, and petroleum-based manufacturing. Wisewool(™) strong wool products eliminate the problem - zero harmful VOCs, zero chemical flame retardants, zero adhesive binders, and independently verified chemical purity at the raw fibre level through NZWTA testing.
Wool meets fire standards by nature - not by chemical addition.
Author Bio: Harry Urquhart-Hay is Co-Founder of Wisewool, a fifth-generation New Zealand strong wool company. Wisewool controls the wool journey from 250+ partner farms in Gisborne through to finished product, and is currently conducting a three-year MPI-funded clinical sleep science study.
Key Sources
NZWTA Pesticide Residue Testing, IWTO-DTM-59, Report Numbers 1-01470007.E4 and 1-01470008.E2
NZWTA Fire Safety Testing, BS 5852:1979 & BS 5852:1982, Certificate 1446262.6A–D
McNeil, S. (2015). The Removal of Indoor Air Contaminants by Wool Textiles. AgResearch Technical Bulletin. Available: researchgate.net/publication/353757473
IWTO (2025). Breathe Easy With Wool. International Wool Textile Organisation Fact Sheet. Available: iwto.org
Oz et al. (2019) and Boor et al. (2014) — VOC emissions from polyurethane mattresses, cited in: Evaluation of VOC emissions from memory foam mattresses and potential implications for consumer health risk. ScienceDirect, 2022.