99/02776 Air quality in Beijing and its transition from coal burning caused problems to traffic exhaust related pollution

Abstract

Air pollution in Beijing is characterized by coal smoke for a long time because of energy structure highly dependence on coal consumption. SO{sub 2}, TSP, and NO{sub x} ambient concentration are kept in high levels, which exceed the guideline of WHO and National Air Quality Standard NAQS. The trend of SO{sub 2} change is relative stable, its annual average concentration fluctuates around 100 g/m{sup 3} since 1981. TSP show a fast decrease before 1986 and keep a slow decrease afterwards approaching the level of about 300 g/m{sup 3}. NO{sub x} concentration increases continuously all the time. Since 1993, NO{sub x} concentration exceeds SO{sub 2} to be the important pollutant next to TSP in Beijing, especially in summertime and traffic busy areas. As the consequence of NO{sub x} fast increase, the ozone pollution level is elevated greatly since 1980s. Several integrated field measurements were conducted to study the characteristics of photochemical smog and its formation mechanism. Hourly averaged ozone concentration usually exceeded the NAQS (80 ppb) in April to October. The O{sub 3} formation is very sensitive to NO{sub x} concentration because of the high NMHC/NO{sub x} ratio. In recent years, high O{sub 3} concentration is observed in early Spring and more » photochemical smog pollution is getting more and more severe with dramatically increase of vehicles in downtown Beijing. It is predicted that O{sub 3} pollution will be expected to enhance greatly in next 20 years under the development plan of future urban transportation system and increment of vehicles, even in the case that control strategies suggested by municipal government are undertaken. So more strengthen control strategies in Beijing are needed. « less