This question cannot be answered easily because it depends on many factors, such as thickness and quality of materials used in production. If we were to choose one product that we trust for its safety measures then it would have to be aluminum (especially if you buy a model with high density insulation). It can resist fire up to 1200 degrees Fahrenheit and has been recommended by most home inspectors when using this type of heating element. Plus, there are even manufacturers whose products meet ASTM standards which means they create safe ways of venting smoke from your house! Find these options here.