First, car components and the inner decoration materials contain the release of harmful substances, which include organic solvent, catalyst, additive and other volatile ingredient in the plastic and rubber components, textile materials, oil paint and dope, thermal insulation materials, binding agent which used by the car.  The main pollutant is benzene, toluene, formaldehyde, hydrocarbon, alkyl halide, etc. Furthermore, the substance emitted by the materials inside the car is also the main source of the nasty smell.

Second, outside pollutant comes into the car to cause pollution. And the main pollutant is hydrocarbon, carbon monoxide, carbon dioxide, nitrogen oxide, particles, etc.

Third, the emitted pollutant from the car comes into the car, which includes the pollutant emitted from vent-pipe, crankcase and fuel evaporation, or the accumulated feculence in the wind channel because of the long term use of the car air-conditioning. The main pollutant is hydrocarbon, carbon monoxide, nitrogen oxide, microorganism, benzene, alkene, and aromatic hydrocarbon, etc.