Polyfoam, or polyurethane foam to give it its full name, usually has a chemical smell when first delivered. This is due to the VOCs (volatile organic compounds) that are both used in its manufacture and released into the atmosphere when unpacked. This is known as off-gassing and we were unable to find any users of this mattress complaining of off-gassing. Even if it did off-gas, it is only for a very short time: no more than other 100% synthetic foam mattresses.