pm2.5 英语四级作文

PM2.5 refers to the atmosphere diameter less than or equal to the particles 2.5 microns, also known as pm2.5. Although PM2.5 only group content of a few earth atmospheric composition points, but it has an important influence on air quality and visibility. PM2.5 small particle size, rich in a lot of toxic, harmful substances and residence time in the atmosphere of long, long conveying distance, and thus the impact on human health and the quality of atmospheric environment of the greater. In 2012 February, the State Council agreed to the release of the newly revised "environmental air quality standards," added PM2.5 monitoring index. In September 9, 2012, the Beijing Municipal Environmental Protection Bureau monitoring center said, the new air quality from January 1st 2012 online publishing platform. Beijing city environmental monitoring center station said in 2012 October Beijing is expected to incorporate PM2.5 into the new evaluation system of air quality.