Cold foam is urethane foam and is called cold foam because it is not heat – cured like foam latex; urethane foam cures at room temperature. Cold foam (Kryolan® makes a urethane foam soft enough for prosthetic work) is an alternative to foam latex and could be a good place to begin working with foam instead of with latex simply because it does not require a lengthy heat cure and can be ready to use quickly. Cold foam is not to be confused with poly foam, which is also flexible urethane foam but has a different use and density associated with it.
That said, urethane foam is not a substitute or replacement for foam latex. It is a different material with different properties. It is soft foam suitable for facial and body appliances, but even at its softest, it’s not as soft and pliable as foam latex.
You will probably want to work with good ventilation and might actually want to wear a NIOSH-approved respirator (for the ammonia vapors), but working with foam latex does not mandate that you do so; it is not inherently dangerous to your health. Cold foam, on the other hand, contains isocynates, which are considered quite toxic. It is strongly suggested that latex, nitrile, or vinyl gloves be worn in addition to a respirator. At no time should the components of foam in its liquid state come in contact with the skin or clothing; they will adhere to most surfaces, so it is important to wear proper protection when you handle the liquid components.