The danger from Styrofoam comes when the smoke from burning it releases harmful amounts of PAH (Polycyclic Aromatic Hydrocarbons). According to the Illinois Dep

The danger from Styrofoam comes when the smoke from burning it releases harmful amounts of PAH (Polycyclic Aromatic Hydrocarbons). According to the Illinois Department of Public Health, it is known that PAH stays in the environment for years; has been linked to short-term symptoms like eye irritation, nausea, vomiting, diarrhea and confusion, and long-term symptoms like kidney and liver damage and cataracts. https://www.atsdr.cdc.gov/phs/phs.asp?id=120&tid=25 https://www.atsdr.cdc.gov/phs/phs.asp?id=120&tid=25