The study and the analysis of the data about a high flammability (class KM5), combustibility (В3), inflammability (class G3-G4), velocity of burning velocity speed (РП3), smoke generation capacity (D3), toxicity of combustion products of the polystyrene foam which have an over-cumulative action (carbon oxide, hydrocyanic acid, benzyl, phenyl ethylene) (Т3 – Т4) were carried out. It was suggested to reduce the use of the polystyrene foam in construction by means of replacing it with inflammable materials.

Keywords: polystyrene foam, flammability, toxicity, maximal allowable concentration (MAC), carbon oxide, carbon dioxide, hydrocyanic acid, benzyl, phenyl ethylene, thermal destruction, smoke formation.