Atmospheric particulate matter refers to solid or liquid particulate matter dispersed in the atmosphere. According to its particle size, it can be divided into total suspended particulate matter and inhalable particulate matter. At present, inhalable particulate matter (less than l0um) is the primary pollutant of the urban atmospheric environment in my country, which can cause serious harm to the human body. In addition, it will also affect visibility, acid deposition, cloud and precipitation, atmospheric radiation balance, stratosphere and The chemical reaction of the troposphere has an important influence.

Particles with an aerodynamic scale greater than 10 um are basically blocked in the human nasal cavity; particles with 2 um -10 um can enter the human throat, about 90% can enter and deposit in various parts of the respiratory tract, and 10% can reach the lungs 100% of particles smaller than 2 um can be inhaled into the alveoli, and almost all particles of 0.3 um-2 um are deposited in the lungs and cannot be exhaled, and then enter the human blood circulation.

Due to the small particle size and large specific surface area of the inhalable particles, they are highly adsorbable and easily become carriers of various toxic substances in the air, especially polycyclic aromatic hydrocarbons, polycyclic benzenes, heavy metals and trace elements, etc. The incidence of carcinogenic, teratogenic, and mutagenic is significantly increased. For every increase of 10 ug/m3 of inhalable particulate matter in the air, the risk of death from lung cancer increases by 8%, the death rate from heart disease increases by 6%, and the total mortality rate increases by 4%. The study did not find mortality, total suspended solids, and crude Particle related.

Apart from adverse effects on human health, inhalable particulate matter also has important effects on visibility, acid deposition, clouds and precipitation, atmospheric radiation balance, and chemical reactions in the stratosphere and troposphere. Such as: particulate matter in the atmosphere weakens the radiation of sunlight on the ground, affects the energy budget of the ground and the atmospheric system, and affects the climate, including lowering the surface temperature, affecting wind speed, wind direction, etc.; metal oxides, sulfates and chlorides in the air Dust particles have a catalytic oxidation effect on sulfur dioxide. They are condensation nuclei of sulfuric acid aerosols. They can absorb SO2, SO3 and H2SO4 in the air under a certain humidity environment to generate larger droplets, forming a gas dispersed in the air. Sol, which causes acid rain: the exhaust from cars in cities and suspended particulate matter in the air can form photochemical smog pollution under certain light radiation conditions, producing a large number of secondary aerosol particles, mainly Aigen nuclear particles (0.01=0.1um) and accumulation modal particles (0.1-2um), especially accumulation modal particles, have the largest extinction coefficient, which is the main reason for the obvious reduction of atmospheric visibility during the photochemical smog pollution period.

Therefore, particulate matter in exhaust pollutants must be removed