Polyurethane Foam - which type offgasses least?
Dec 5, 2011 10:33 PM
Joined: Dec 5, 2011
Points: 7


Because of chemical-sensitivity issues, I am not all that thrilled at all about buying a mattress with polyurethane foam, or purchasing a foam component to build my "sleep system" - but for ergonomic reasons, I may have no choice (yes, I've tried the supposedly "healthier" latex - it didn't work out).  So I wanted to ask this forum - what properties should I look for in foam that would minimize my exposure to offgassing substances and toxic flame retardants?

Is it true that the softer (in ILD) the foam is, the more it offgasses - or is the opposite true?  What about densitity - how does increasing densitiy affect the amount of offgassing?  Are there certain types/brands of foam that are known to offgass less than others?  Does the amount of flame-retardant used in the foam vary with firmness-level and/or densitiy? 

While I'm at it - I might as well ask if anyone knows of any particular brand of mattress that has little-to-no offgassing?  Which would be the lesser of the evils as far as this is concerned?  (My budget is quite limited - I cannot spend more than $800 on this mattress.)

Thanks for any feedback...

Re: Polyurethane Foam - which type offgasses least?
Reply #8 Dec 14, 2011 3:08 PM
Joined: Dec 17, 2009
Points: 850
Talking about various types of breakdown and decay of polyurethane foam versus synthetic latex (SBR) and natural latex (NR).  Things are a little different. 

It is true that in a landfill we have no idea how long polyfoam will stay around for, it does not readily bio-degrade.  So this process could take hundreds or even thousands of years. SBR is somewhat similar as well, it does not readily biodegrade, although because it is not plastics based it might break down a little quicker.  Natural rubber would break down pretty quickly in comparison.  

WIth regards to breakdown from functional use in a mattress, natural rubber or even synthetic latex lasts a lot longer than polyurethane based foams.  Polyurethane  softens a lot from use, this is loosely related at best to the chemical off-gassing component, and has more to do with the cell structure of the foam simply being more brittle and less elastic than natural rubber.  

With regards to the various types of odours and what really causes them.  With polyurethane foams a lot of people assume that chemical off-gasing is somehow a temporary thing; this is because the odours are always much stronger when the mattress is brand new and will dissipate with time. In truth the off-gasing is indefinite, the product does break down over time, as all polymers do. Most of the chemicals released over time are odourless, or are odourless below a certain concentration.  For instance formaldehyde below something like 20 ppm (parts per million) is usually undetectable.  Above that, it can have a pretty powerful odour to some people.  

Synthetic latex does have a distinctive chemical type smell to it, I would say less so than polyurethane foam...I do not mean to be argumentative because obviously what you experienced was very real to you...but I would not describe it like gasoline.  Gasoline is an incredibly powerful and offensive smell...realistically if the beds smelled like that no one would buy them after laying on them...in any event some people are much more sensitive then others when it comes to these things. 

Natural rubber has a smell that by definition will never go away because its not some kind of chemical additive that causes it...its the natural smell of hevea milk.  It may be very noticeable to some individuals, and not so much to others. But for instance if you walked into a room full of apples....you could smell the apples.  

The reason I suggest cotton filled mattress...is that cotton is relatively odourless as well as non-toxic...its one of the only materials in the world I could list that fits both of those criteria. 

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