Now there are about 180 million motor vehicles in China. The exhaust gas discharged by them has become the “number one killer” for our cities’ air quality. The main pollutants included in the motor vehicle exhaust gas are CO, hydrocarbons, nitrogen oxide and soot particles. These pollutants are fully permeated in the breathing zone of us, very harmful to both the environment and our health. Such as in the hydrocarbons, there are the strong carcinogens of benzene and other polycyclic aromatic hydrocarbons(PAH) composition.  The nitrogen oxide has the long potential harm to the people’s health. When serious, it can lead to the disease of eyes, nose and lungs, even the cancer. For the soot particle, it can not only generate the visual pollution, the small particle can also enter into the respiratory passage and deposite of our lung cell, thus leading to the respiratory illness, even the lung cancer.