Monitoring the degradation of physical properties and fire hazards of high-impact polystyrene composite with different ageing time in natural environments.

•The flame retardant HIPS composites were firstly ageing in Turpan and Qionghai.•The color changes of HIPS composites increases with the natural irradiation dose.•The surface degradation and flame retardant migration were more intense in Qionghai.•The fire hazard of HIPS composites increases with increasing the natural ageing time.•The mechanical property of HIPS composites deteriorated more seriously in Qionghai.