Analysis on Variation Characteristics of Air Pollution Index in Cangzhou

Abstract

On the basis of the daily air pollution index (API), primary pollutant, air quality level and status in Cangzhou from January 2009 to December 2012, the variation characteristics of air quality were analyzed. The results showed that API presented obvious seasonal variations with the highest value in winter and the lowest value in summer. PM10was the principal pollutant and accounted for 63% of the whole period. The percentage of excellent and good air quality was 93% during the period. The relationship between API and meteorological factors indicated that API was negatively correlated with temperature and relative humidity, but was not obvious correlation with air pressure and wind speed. The cluster analysis of backward trajectories showed that different types of air masses contribution to the API level showed some differences in different seasons. The north air mass in fall and northwest air mass in summer had the lowest contribution to the API level; while the local source could lead to the highest API level in winter suggesting that the heating and adverse weather conditions in winter may be the main cause of high API.