The machine construction sector uses from 2 to 5% of thermoplastic polymer produc-tion. This material is used to make small elements and big parts of equipment, includ-ing guards. The latter have mechanical vibration damping capacity, do not require any maintenance, are cheap and look attractive. Moreover, polymer guards are an essen-tial element of machines as they improve workplace safety. They are used in such ma-chines as lathes, milling machines, drills, extruding machines, presses and grinders. Pursuant to the Ordinance of the Minister of Labour and Social Policy on general provi-sions for safety and health at work, protective devices used in machines should be strong and durable so as to ensure the appropriate level of occupational safety. This is why the selection of the right material to make such devices is essential. Most fre-quently guards used in the market are steel frames with a polycarbonate screen or lam-inated safety glass. Other materials used to manufacture guards are poly(methyl methacrylate) (PMMA) and polystyrene (PS). Thermoplastics are characterised by high visual light transmittance (even up to 98% in the case of PMMA), easy treatment, pos-sibility to form any shape and resistance to atmospheric factors. However, they are also characterised by limited high temperature resistance, low fire resistance and high speed of fire propagation on their surface which may be dangerous for employees in case of fire. The article discusses the selection of appropriate material for the produc-tion of guards in the context of their exploitation in higher temperature conditions and examines threats posed by thermoplastics in fire conditions.