Automobile exhaust mainly refers to the exhaust gas discharged from the exhaust pipe. Waste gas contains 150 ~ 200 different compounds, among which carbon monoxide, hydrocarbons, nitrogen oxides, lead compounds and particulate matter are the most harmful to people. The diffusion of harmful gases into the air will cause air pollution. The particulate matter in automobile exhaust contains a strong carcinogen benzo (a) pyrene. Under normal circumstances, 1 g particulate matter contains about 70 micrograms of benzo (a) pyrene, and every 1 kg gasoline can produce 30 milligrams of benzo (a) pyrene. When the concentration of benzo (a) pyrene in the air reaches 0.0 1.2 μ g/m3, the number of people suffering from lung cancer will increase obviously. Because the emission of automobile exhaust is mainly between 0.3m-2m and 2 m, which is just the breathing range of human body, it is very harmful to human health-stimulating the respiratory tract, reducing the immunity of the respiratory system, leading to a series of symptoms such as chronic bronchitis, bronchitis, dyspnea, and decreased lung function. Benzene, a strong carcinogen contained in tail gas, can cause lung cancer and thyroid cancer.