Study on Characteristic of Persistent Air Pollution in Beijing from 2000 to 2010

Through the air quality daily report in Beijing from June 2000to December 2010,the characteristics of the persistent air pollution in Beijing were analyzed.The result showed that the air quality has been significantly improved in Beijing in recent 10years.The persistent air pollution days and the exceed air quality standard days appeared decreasing trend,but the persistent pollution days account for the proportion of pollution days is still a large,persistent pollution has become a distinctive feature of air pollution in Beijing.Spring is the season of the most persistent air pollution days,average 25.4days per year.Summer is the season with minimum days of persistent air pollution,but the persistent pollution caused by wheat-straw burning often occurs in June.Distribution of persistent air pollution in Beijing can be divided into three types:Dust storm type,pollution accumulation type and wheat-straw burning type.Distribution characteristic of the persistent air pollution effected by dust storm is high API in the whole Beijing,expecially in urban area and southwest of Beijing.The distribution characteristic of the persistent air pollution of pollution accumulation type is of‘higher in the south than north’.The distribution of persistent air pollution of wheat-straw burning type is high API in the suburbs.