Influence of DSSs on urban air quality in China during 2005–2010 and analysis of a severe DSS event

摘要

In each year, Dust and Sandstorms (DSSs) triggered by cold air masses enhance particle concentration over large areas in China during spring and winter. In this paper, daily Air Pollution Index (API) of 113 major cities in China during dust events was analyzed to present the influence of DSSs on urban air quality. From 2005 to 2010, a total of 93 dust events were identified, on average there are approximately 16 dust events in a year. The number of total polluted days caused by DSSs in 113 major cities ranged from 147 to 546 each year, with maximum in 2010 and minimum in 2007. The number of total heavily polluted days caused by DSSs in major cities ranged from 14 to 78 each year, with maximum in 2010 and minimum in 2005. DSSs affected major cities most severely during March to May. Furthermore, a typical DSS observed from 26 to 31 May 2008 was described in terms of meteorological features and PM10 concentration as well as API levels of 113 major cities. This event lead to high PM10 concentration and low visibility over major cities, with maximum daily PM10 concentration of 1511 μg m−3 in Chifeng on 28 May, which was directly caused by strong wind in front of surface high pressure system passing through sand source areas in Mongolia and North China. The most severe pollution occurred on 29 May, with 38 cities polluted and 7 cities heavily polluted.