The main pollutants are carbon monoxide, hydrocarbons, nitrogen oxides, sulfur dioxide, lead compounds, benzopyrene and solid particles, which can cause photochemical smog. Others include carbon dioxide (CO2), sulfur compounds SOx (SO and SO2), nitrogen oxides NOx (NO and NO2), hydrochlorofluorocarbons, etc.

Carbon monoxide (CO) : In internal combustion engines, CO is a colorless, odorless gas produced when insufficient air or other reasons cause incomplete combustion. CO after human body, very easy to combine with hemoglobin in the blood, its affinity is 300 times that of oxygen. So. The hemoglobin in the lung does not combine with oxygen and CO, resulting in hypoxia in the human body, causing headaches, dizziness, vomiting and other poisoning symptoms, serious may lead to death.

Hydrocarbon (HC) : NOx is a brown, pungent odor exhaust gas produced in large quantities when the engine is under a certain load. When the engine exhaust gas is just discharged, the toxicity of NO in the gas is less, but it is easy to be oxidized into NO2 and other nitrogen and oxygen compounds with greater toxicity. NOx can form nitrous acid and nitric acid after entering the alveoli, and produce severe stimulation on lung tissue.

Particulate Matter (PM) : The particulate matter emitted from the combustion chamber comes from three sources: the non-combustible matter (Particulate Matter), the matter that is combustible but does not burn, and the combustion matter (particulate matter). Most of the particulate matter emitted in the combustion process is solid carbon, and the solid carbon particles formed in the flame are called carbon black.