PM2.5英文介绍.pptVIP

PM，an abbreviation for Particulate Matter, refers to liquid or solid particles suspended in the air. Depending on their origin and visual appearance, aerosols have acquired different names in the everyday language. Dust refers to solid airborne material, dispersed into aerosol from grainy powders such as soil. Combustion processes produce smoke particles, but the incombustible residues of coal are called flyash. In the early days, air pollution had the appearance of both smoke and fog, so the term smog was created. In the open atmosphere, the visibility may often be reduced by regional haze, originating from various natural or anthropogenic sources. Neither water droplets of fog and clouds, snow, rain, sleet (hydrometors) nor dust particles larger than 100 um (blowing sand) are considered to be particulate matter What is “ＰＭ” ? What is PM2.5 ？ The name PM2.5 denotes that it includes all particulate matter that has an aerodynamic diameter of 2.5 microns or smaller. 2.5 micrometers is approximately 1/30 the size of a human hair. PM2.5 also called fine particulate lodges deeply into the tissue of the lung and is not easily dispelled. It causes both respiratory and cardiac illness, and has been linked to premature mortality even in healthy individuals. PM Formation in the Atmosphere The sources of PM2.5 include fuel combustion from automobiles, power plants, wood burning, industrial processes, and diesel-powered vehicles such as buses and trucks.These fine particles are also formed in the atmosphere when gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds (all of which are also products of fuel combustion) are transformed in the air by chemical reactions. PM2.5 Health Effect Increased levels of fine particles in the air as a result of anthropogenic particulate air pollution is consistently and independently related to the most serious effects, including lung cancer and other cardiopulmonary mortality. The large number of deaths and other h