What is off-gassing?#

Off-gassing refers to the release of volatile organic compounds (VOCs) from newly manufactured foam materials. When a foam mattress is compressed and vacuum-sealed for roll-pack delivery, VOCs build up inside the sealed packaging. When you unpack the mattress, these compounds are released into the air, producing the distinctive "new mattress smell" that most buyers notice.

VOCs are released not just by mattresses but by many household items including carpets, paints, furniture and cleaning products. The "new car smell" is also VOC off-gassing from synthetic interior materials.

Is off-gassing harmful?#

For most people, mattress off-gassing from a quality foam mattress is not harmful. The concentrations of VOCs released are typically low and dissipate within 24–72 hours of unpacking. Most modern foam mattresses sold in the UK use foam certified to safety standards (CertiPUR-US, OEKO-TEX Standard 100, or similar) that test for and restrict the most harmful VOC compounds.

Some individuals who are chemically sensitive, have severe asthma or are pregnant may experience headaches, nausea or respiratory irritation during the initial off-gassing period. If this applies to you, follow the ventilation steps below carefully and consider leaving the mattress to air for 48–72 hours before sleeping on it.

Which mattresses off-gas most?#

Off-gassing intensity varies by material:

  • Memory foam: Most significant off-gassing, particularly with lower-quality or non-certified foam
  • Polyurethane (cold) foam: Less than memory foam but still present
  • Latex: Natural latex has a mild natural rubber smell, not VOC-based. Synthetic latex off-gases more.
  • Natural fillings (wool, cotton, horsehair): Negligible off-gassing

How to ventilate quickly: step by step#

  1. Unpack the mattress in the room where it will be used (don't unpack in a closed van or garage)
  2. Open all windows and doors in the room and maintain cross-ventilation
  3. Run a fan directed at the mattress surface to accelerate VOC dispersal
  4. If possible, leave the mattress to air for 24–48 hours before making it up and sleeping on it
  5. Wash your hands after handling the packaging materials

In most cases, the noticeable smell will be gone within 24 hours and undetectable within 48–72 hours. If a strong smell persists beyond 72 hours with good ventilation, contact the manufacturer, persistent strong odour may indicate a quality issue with the foam.

Reducing off-gassing: buying tips#

  • Choose mattresses with CertiPUR-US or OEKO-TEX certification, these test for specific harmful VOC compounds
  • Natural latex and wool mattresses have minimal off-gassing
  • Some brands now offer "airing periods" (they deliver the mattress to a warehouse and let it off-gas before sending to you), ask if your brand offers this

Which of our mattresses smell least on arrival#

All new mattresses smell of something; the question is how strong and how long. From unboxing dozens, here is how the types in our catalogue compare.

TypeExampleTypical smellClears in
Natural latex hybridLuxeOrganic Hybrid LatexFaint, slightly sweet rubber1–2 days
Pocket-sprung hybridLuxe Velour HybridMild; mostly the packaging1–3 days
Dense memory foamEmma OriginalNoticeable chemical note on unrolling3–7 days
Budget memory foamWestwood Memory FoamStrongest of the groupUp to 2 weeks

None of this is a health concern for a mattress carrying CertiPUR, OEKO-TEX or equivalent certification; the compounds are at low levels and drop quickly. It is a comfort issue. If smell bothers you, choose springs or latex, unbox in a ventilated room, and leave it a day before making the bed. Our unboxing guide has the full routine.

Frequently asked questions#

Is mattress off-gassing dangerous?#

For a certified mattress, no. The smell is volatile organic compounds released as compressed foam expands, at levels that fall to background within days. People with asthma or chemical sensitivities may notice irritation while it airs; ventilate and wait a day or two.

How long does off-gassing last?#

Most of the smell goes within 24–72 hours with a window open. Dense or budget memory foam can be faintly noticeable for one to two weeks. If a strong smell persists beyond that, contact the retailer.

Which mattresses do not off-gas?#

None entirely, but natural latex, wool and cotton mattresses and pocket-sprung mattresses with thin comfort layers have the least. Anything with a thick polyurethane or memory foam layer has the most.

Can I sleep on a mattress the first night?#

Yes. If the smell is strong, air it for a few hours first and sleep with the window open. Most brands say the mattress is usable immediately; the airing is for your comfort, not the mattress's.