Most Likely Causes (Ranked)
Memory foam and conventional polyurethane foam are the primary off-gassing sources in modern mattresses. These materials are made through a chemical reaction (polymerization) that produces a solid foam, but residual reactants, solvents, and processing chemicals remain in the foam matrix and slowly volatilize at room temperature. The most commonly detected VOCs from foam mattresses include toluene, ethylbenzene, xylene, benzene, formaldehyde, and acetaldehyde. These compounds produce the characteristic 'new mattress' or 'new car' smell that most people associate with freshly unpackaged foam products. The compression and vacuum sealing during shipping concentrates the vapors; opening the package and allowing the mattress to expand releases a concentrated burst.
US federal law (16 CFR Part 1633) requires mattresses to meet specific open-flame resistance standards. To meet these requirements, manufacturers add flame retardants — either chemical treatments applied to cover fabrics, barrier layers, or additives in the foam itself. Some flame retardant systems involve chemical compounds that off-gas. Most modern manufacturers use silica-based or Kevlar barrier systems rather than PBDE-type chemical flame retardants, but residual smell from cover treatments can still be present.
Many mattresses — especially hybrid and pillow-top models — use adhesives to bond foam layers, attach pillow tops, and secure cover materials. These adhesives are typically solvent-based or water-based polymer adhesives that off-gas as they cure. The adhesive smell tends to have a slightly sharp, glue-like or acetone-like character. As adhesives fully cure, the smell dissipates.
Natural latex mattresses have their own characteristic smell — described as sweet, rubbery, or slightly vanilla-like. This comes from the natural rubber proteins in latex and from the vulcanization process used to turn liquid latex into solid foam. While this smell is different from synthetic foam off-gassing, it can still be strong enough to be unpleasant for some people. The smell is generally more pleasant and fades quickly compared to synthetic foam.
Some manufacturers use natural wool as a flame retardant barrier (wool is naturally flame resistant). New wool has a lanolin and sheep-like smell that many people find unpleasant in a fresh mattress. This smell is biological rather than chemical and fades with airing.
How to Fix It
Air Out the Mattress
FreeThe most effective approach — time and airflow solve the problem for most mattresses.
- 1Unbox and unroll the mattress in a well-ventilated room. Open windows and run a fan to maximize airflow across the mattress surface.
- 2Leave the mattress uncovered (no sheets, no protector) for the airing period — covers trap the off-gassing vapors.
- 3If possible, stand the mattress vertically against a wall with a fan on each side — this aerates both surfaces simultaneously and speeds the process.
- 4Allow at least 48-72 hours of airing before putting sheets on. Many manufacturers recommend 72 hours to a week.
- 5If the smell is strong: repeat with the mattress flipped after the first 24 hours to ensure both sides air equally.
- 6Baking soda applied to the surface (let sit 4-8 hours then vacuum off) can absorb some surface VOCs and accelerate the fading process.
Ventilate the Room Aggressively
FreeConcentrate the airflow to accelerate VOC dissipation.
- 1Create cross-ventilation: open windows on opposite sides of the room if possible.
- 2Run a ceiling fan or box fan pointed toward the mattress.
- 3If weather permits, move the mattress outside for a day in a covered area — outdoor airflow dramatically accelerates off-gassing.
- 4Run the room's HVAC with the bedroom door open to exchange air.
- 5An air purifier with activated carbon helps adsorb VOCs from the air during the airing period — useful for sensitive individuals.
When to Call a Professional
You or a family member has severe chemical sensitivities or respiratory conditions — allow extra airing time (1-2 weeks), choose a mattress with a GREENGUARD Gold or OEKO-TEX certification that limits VOC emissions.
The smell is still very strong after 2 weeks — this is unusual. Contact the manufacturer, as some mattresses have manufacturing defects resulting in abnormally high off-gassing.
You experience headaches, dizziness, or eye irritation in the bedroom — don't sleep on the mattress until fully aired. Ventilate the room thoroughly.
How to Prevent It
Choose certified low-VOC mattresses — GREENGUARD Gold (formerly CertiPUR-US for foam) and OEKO-TEX certifications limit maximum allowable VOC emissions. These mattresses still off-gas but at lower levels.
Allow the mattress to air for 72 hours before first use — ideally in a separate room from where you sleep.
Consider natural latex or organic mattresses — they generally have lower synthetic VOC content, though they have their own natural material smells.
Is New Mattress Off-Gassing Actually Dangerous?
This is a frequently asked question, and the honest answer is: at typical exposure levels, probably not for healthy adults — but the research is limited enough that caution is warranted.
The VOCs detected in mattress off-gassing studies include known and suspected carcinogens (benzene, formaldehyde) and respiratory irritants (toluene, xylene). However, the concentrations measured in typical bedroom settings during normal off-gassing are generally below occupational exposure limits established by OSHA and NIOSH — limits set to protect workers with daily, year-round exposure far more intensive than what consumers experience.
For most healthy adults, the VOC concentrations in a bedroom with a new mattress pose minimal acute risk. The population most worth protecting are infants (who sleep 12+ hours per day on the mattress and have smaller respiratory volumes relative to size), children, and people with respiratory conditions like asthma or COPD. For these groups, thorough airing (72 hours minimum), certified low-emission mattresses, and maintaining good bedroom ventilation during the first weeks are reasonable precautions.
Frequently Asked Questions
For most foam mattresses: the strong initial smell fades within 1-3 days of airing. A faint residual smell may persist for 1-2 weeks. Full off-gassing of all detectable compounds typically takes 1-3 months, though at levels too low to smell by 2-3 weeks in most cases. Memory foam tends to off-gas longer than standard polyurethane foam. Natural latex typically fades within 1-2 weeks.
For healthy adults: yes, it's generally considered safe, especially if the bedroom is ventilated. If the smell is very strong (strong enough to cause immediate eye or throat irritation when you enter the room), air it out for 48-72 hours before sleeping on it. For infants, children, pregnant women, or people with respiratory conditions, more thorough airing is recommended.
Maximum airflow is the fastest approach: uncover both sides, stand the mattress if possible, use multiple fans, and open all windows. Moving the mattress outside for a day in dry weather (not direct sun, which can damage some foams) provides the best airflow. Baking soda on the surface absorbs some surface VOCs. Activated carbon air purifiers help with room air quality during the airing period.
Yes — a waterproof mattress protector creates a barrier that traps VOCs and prevents them from dissipating. Don't put a protector on until the mattress has fully aired. Some people find that the protector traps the smell and reintroduces it every time they remove the protector for washing — this is just the protector concentrating residual vapors that have built up under it, not new off-gassing.