Polyurethane Foam

The isocyanate worry is real but belongs to the factory, not the living room. A 2013 study found cured flexible foam carrying 56 to 2,800 ng/g of solvent-extractable TDI and yet detected no TDI at all in either air-emission or skin-migration testing of the same foam, with the method demonstrated capable of finding it; EPA's own consumer concern is with products sold uncured, such as sealants and adhesives. Off-gassing is measurable and small: a 2022 study of two new memory-foam mattresses found emissions peaking on day one, dominated by 2-propanol, acetone, chloromethane and toluene, with a 32-day average total VOC of 20 to 33 ug/m3 falling to 2.7 to 4.2 ug/m3 over a year, which the authors described as well below available health-based benchmarks. New-mattress smell is real and the odour thresholds sit far below the health ones - airing it out for a few days catches most of it. The genuine harm in this material's history is flame retardants: pentaBDE was widely used in US furniture foam until industry stopped production at the end of 2004, and older foam still acts as a long-lived reservoir feeding house dust. One claim to discount: the widely repeated finding that cleaning sponges shed trillions of microplastic fibres is about melamine foam, not this, and no equivalent measurement exists for polyurethane.

Everyday heat does nothing to it. The first bonds in the polymer, biuret and allophanate, do not begin breaking until around 100 to 125C, and the urethane and urea bonds hold to 160 to 200C, far above body heat or a parked car. The hazard is fire, not warmth. Flexible PU foam has low thermal inertia and ignites readily, and the yields of the two gases that actually kill people rise sharply when a fire goes under-ventilated, which is the normal case in a closed room: measured carbon monoxide went from 26 to 143 mg/g and hydrogen cyanide from under 3.0 to 8.8 mg/g between well- and under-ventilated furnace conditions. That is why furniture flammability standards exist at all.

It compresses and springs back, which separates it immediately from melamine foam (rigid, crumbly, abrades away as you use it) and from cellulose (stiff dry, soft and absorbent wet). Memory foam is the same chemistry with a slow-recovery formulation. EVA, the usual shoe-midsole foam, is closed-cell, lighter and squeakier. On US upholstered furniture, the useful label is the TB117-2013 tag required since 2015, which states in plain words whether the upholstery materials contain added flame retardant chemicals or contain none. For a mattress, ask what the certification actually covers: CertiPUR-US tests the foam only, not the cover, adhesives, barrier or finished product, and never claims the foam is non-toxic.

Mattress and cushion foam is polyether-based and ages by slow oxidation. It yellows almost immediately, which is cosmetic, and softens and loses support over roughly five to ten years. The foam that famously turns sticky and crumbles into orange dust - old speaker grilles, camera-case inserts, headphone earpads - is polyester-based foam hydrolysing, a different formulation that is not what mattresses are made of. UV and humidity accelerate both routes, so foam stored in a hot garage or a sunny window degrades faster than foam in use.

Not accepted curbside anywhere. The one real recycling outlet for recovered flexible foam is rebonding it into carpet underlay, and that is where most of it goes when it goes anywhere. Mattress take-back programs that actually separate and recover foam run in only four US states - California, Connecticut, Oregon and Rhode Island - and elsewhere a mattress is landfilled whole. The material neither composts nor breaks down.