Is spray foam toxic after it dries?

Spray foam after it fully cures and dries is generally considered non-toxic and safe for occupants, as chemical reaction completes and foam becomes inert solid. Fully cured closed cell and open cell spray foam does not off-gas significant amounts of toxic chemicals and is safe to be around. However, during installation and curing period of 24 to 72 hours, spray foam can be toxic due to isocyanates and other chemicals that can cause respiratory irritation, skin irritation, and chemical sensitization, requiring vacating building and proper ventilation and protective equipment for installers. If spray foam is improperly mixed or installed at wrong temperature or ratio, it may not cure properly and can continue to off-gas with strong odor and remain toxic longer, requiring removal. Once fully cured, spray foam is stable, does not release toxic fumes under normal conditions, though if burned it can release toxic smoke like many building materials. So after proper curing, spray foam is not considered toxic, but during installation it is hazardous and needs precautions.