PVC is a thermoplastic derived from chlorine (from industrial grade salts) and carbon (mainly refined from oil/gas). Compared to other polymers, it is less dependent on non-renewable crude oil and natural gas, so PVC is considered a natural resource-saving plastic compared to oil-dependent plastics such as PE, PP, PET and PS. Chlorine imparts excellent fire resistance to PVC: When PVC is on fire, the flame will extinguish itself due to the self-extinguishing properties of the material.