What mattress off-gassing is – and how to stop the smell

What mattress off-gassing is – and how to stop the smell
(Image credit: New Africa/Shutterstock)

When you’re choosing the best mattress, how it smells might not be the first thing that you consider. However, depending on the type of mattress you buy, you may end up experiencing some unsavoury-sounding ‘mattress off-gassing’.

Its effects can come as quite a surprise. If you’re particularly sensitive to it, or you choose a type of mattress that’s more prone to off-gassing than normal, you may find that you’re not sleeping quite as soundly as you expected.

So, here we’ll be exploring everything about this strangely named phenomenon, from exactly what mattress off-gassing is and whether it’s dangerous, to how to get rid of the smell. We'll also look at whether there’s anything you can do to avoid it in the first place.

What is mattress off-gassing?

At its most basic level, off-gassing is the process in which volatile organic compounds (VOCs) are released from a product into the air in your home. The most common culprits for off-gassing are synthetic and petroleum-based products, including carpets, furniture, and – you guessed it – mattresses.

If you’re not familiar with the technical jargon, ‘volatile’ means that a substance can very easily become a gas, and ‘organic’ means that substance is carbon-based – and the first of the two is what causes off-gassing.

When you’ve bought a wrapped product, upon opening the package you’ve likely smelled a certain ‘chemical’ smell. That’s the product off-gassing, releasing vapors into the air. Predictably the effect is strongest right after the packaging is removed, but certain items can take weeks, months, or even years to off-gas entirely.

Nectar mattress rolled up in a box by a bed

We didn't notice any off-gassing when we reviewed the Nectar mattress, but some users have mentioned an initial odor  (Image credit: Nectar)

VOCs come in many forms, including chemicals like benzene, acetone, formaldehyde and ethanol, and although many VOCs are indispensable during the manufacturing process of mattresses, it’s not ideal to have them evaporating into the air you breathe at home every day. 

Synthetic memory foam is one such material that off-gasses, and many buyers complain of an odd scent shortly after unwrapping even the best mattress in a box options. 

Add to that the fact you spend a lot of time in close contact with your mattress, and if you’re affected by off-gassing, it could become a problem. It's also worth noting that different VOCs have different scents (some are even scentless), so it can be tricky to identify which individual compound affects you the most.

The fact of the matter is that unless you buy second-hand, almost every homeware product will off-gas to an extent. The important thing is knowing if it’s a problem for you, and if it is, how to manage it.

Is off-gassing dangerous?

What mattress off-gassing is – and how to stop the smell

(Image credit: Shutterstock)

Off-gassing isn’t inherently dangerous for everybody, although we do recommend all consumers consider it before making a purchase, especially if you share your home with people who could be vulnerable or young children.

The most common side effects of off-gassing are headaches and minor allergic reactions like eczema and hayfever-like symptoms, but those who have asthma may find certain VOCs affect their breathing. Some VOCs are also thought to cause longer-term issues.

It’s important to note, though, that buying a mattress from a reputable brand that ensures its materials are safe can greatly reduce any risks involved – more on that later.

How long does mattress off-gassing last?

There’s no definite rule to this, and a mattress’s composition will dictate what VOCs are released and for how long.

Some mattresses may lose any scent in a matter of hours, while others take a day or two. Petroleum-based foam (widely regarded as an outdated material) may take weeks to lose the last of its off-gassing odor, so picking a mattress made of the right material is important. And that leads us on to…

Which type of mattresses are most and least likely to off-gas?

As previously mentioned, the materials a mattress is made from will dictate the amount and duration of any off-gassing that may occur.

If you’re worried about off-gassing, it’s worth seeking out an organic or ‘natural’ mattress. Because these products use all-natural materials like latex, cotton, and wool, no (or at least very few) VOCs will be used in the manufacturing process. That means no funky smells, a better night’s sleep from day one, and a more environmentally friendly mattress.

Simple innerspring mattresses with little to no foam of any kind are also quick to lose any odor. This is because they’re essentially a hollow metal frame with a comfortable topping, and the main off-gassing culprit will likely be any fire protection elements. Be aware that the cheapest options may use polyfoam, though, which is notable for off-gassing.

Classic slow-moving memory foam mattresses may be a cheaper alternative to latex, but are more likely to off-gas thanks to their components. Some people have a sensitivity to the polyurethane used in memory foam manufacture – if that’s you, we’d recommend choosing a latex alternative.

Basic polyurethane foam (polyfoam) is the biggest off-gassing culprit. Usually made from petroleum-based materials, it’s cheap, light, relatively comfortable, and easily transported. However, mattresses that use polyfoam can emit more noxious gases (especially if they don’t boast the certifications we outline below), and they also simply don’t last as long in use.

How to reduce the likelihood of off-gassing

What mattress off-gassing is – and how to stop the smell

(Image credit: Shutterstock)

Whether you’re buying an innerspring, one of the best memory foam mattresses or a top-of-the-line all-natural mattress, there are a few official certifications to watch out for, and some things to do to reduce the likelihood of off-gassing.

First of all, unwrap your mattress as soon as possible and let it air out for as long as you can in a vacant, ventilated room or area. This allows the worst of any off-gassing to take place before you come into contact with the mattress. 

Before that point, though, it’s worth checking if you mattress has any of the following certifications:

GREENGUARD Certification: If your mattress is GREENGUARD certified you know that it’s been thoroughly checked and tested, and will not pose a threat to you or your family’s health. The testing focuses on general VOC content, and doesn’t single any one VOC out, so you can be sure nothing has been missed.

CertiPUR-US: This is a certification that is solely aimed at making sure bedding foams are safe for use. You'll find more info in our guide to what a CertiPUR-US certification means for mattresses, but here's the short version. To pass the CertiPUR-US Certification, a foam must be made without ozone depleters; PBDEs, TDCPP, or TCEP fire retardants; mercury, lead, or other heavy metals; formaldehyde; phthalates; and must meet a low general VOC emission level. Plenty of jargon there, but in short, a CertiPUR-US certified mattress won’t have used the worst offenders, and shouldn’t off-gas excessively.

OEKO-TEX 100: Probably the most stringent of all the material certifications, OEKO-TEX 100 allows very low amounts of harmful VOCs or substances to be used in manufacture. Mattresses are in Product Class 2, which is second only to baby products in terms of strictness. Find a mattress with an OEKO-TEX 100 certification, and you can be pretty sure it won’t off-gas.

How to get rid of the off-gassing smell

Helix Midnight mattress review

(Image credit: Helix)

1. Remove the plastic packaging from your mattress ASAP
The easiest way to get rid of any off-gassing scent is to unpack your mattress immediately. If it's a bed in a box (such as the Helix Midnight mattress pictured above) let it unfurl fully. If it's a traditional mattress, such as the Saatva Classic Mattress, make sure all the plastic has been unwrapped. 

2. Open a window
Place your unwrapped mattress in a dry, well-ventilated room that will be empty for the rest of the day. If you can, open a window to help circulate the air.

3. Air your mattress outside
If the off-gassing scent is really bad, some people recommend putting your mattress outside in the sun to ‘bake’ out any VOCs – this works by raising the mattress’s temperature, making VOCs evaporate more quickly.

4. Invest in an air purifier
No device can completely get rid of air pollutants, but the best air purifiers will filter out a lot of airborne particles and may improve respiratory health. Look for a model with HEPA or "HEPA-like" filters - these trap the most airborne particles. 

If possible, wait as long as you can before sleeping on the mattress – although in most cases a day or two should be more than enough.

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Mo Harber-Lamond
VPN Editor

Mo is VPN Editor at Tom's Guide. Day-to-day he oversees VPN, privacy, and cybersecurity content, and also undertakes independent testing of VPN services to ensure his recommendations are accurate and up to date. When he's not getting stuck into the nitty-gritty settings of a VPN you've never heard of, you'll find him working on his Peugeot 205 GTi or watching Peep Show instead of finally putting up those shelves.