Hi Fran,
All materials … memory foam, polyfoam, latex and even fruits and vegetables have offgassing. The real question is whether the offgassing is harmful.
If the polyfoam has been CertiPur certified or if it’s made in North America (see post #12 here) … then by most people’s standards it would generally be considered to be safe but each person may also have a different answer to the question of “how safe is safe enough for me?”. There is more about this in post #2 here and the other posts and information it links to although this will take you down a rabbit hole of conflicting information with answers that are not always clear or depend on specific circumstances or the different sensitivities, circumstances, or beliefs of different people.
Phoenix