中文摘要：

根据中国北方9个典型城市（北京、哈尔滨、青岛、太原、沈阳、大连、呼和浩特、兰州、乌鲁木齐）2002-2008年连续7年的空气污染指数（API）资料,对各月空气污染指数大于200的天数和首要污染物以PM10和SO2出现的天数进行了分析,结果表明冬季污染最为严重,PM10为我国北方9个典型城市（北京、哈尔滨、青岛、太原、沈阳、大连、呼和浩特、兰州、乌鲁木齐）首要污染物。研究还结合北方典型城市空气污染指数的月均值,分析了各地污染的成因;并对环境因素：温度、降水、湿度与空气污染的相关性进行了研究,结果表明：温度、降水与空气污染指数呈负相关;大部分城市湿度与其呈负相关,而乌鲁木齐则为显著的正相关。此外,还以兰州市为例分析比较了不同类型降水对空气污染指数的影响。最后通过比较2006年3月份的一次强沙尘暴期间空气污染指数与2007年同期空气污染指数,讨论了沙尘暴对我国北方空气质量的影响。

英文摘要：

According to the API（air pollution index） data of nine typical cities（Beijing,Haerbin,Qingdao,Taiyuan,Shengyang,Dalian,Huhehaote,Lanzhou,Wulumuqi）in north China during the period between 2002 and 2008,the days and frequencies including API value higher than 200 and PM10,SO2 regarded as primary pollutants were analyzed.The study showed that PM10 as a primary pollutant and mainly contributed to the severe air pollution of nine typical cities in winter.In addition,the causes of air pollution in the selected cities were deduced using monthly mean of API.Furthermore,the correlations between the environmental factors including climate temperature,precipitation and humidity and API were studied,and the results indicated that there was a good negative correlation between API and both of temperature and precipitation.The results also exhibited that a negative correlation existed between the humidity and API in the most cities except Wulumuqi,which was significant positive correlation.but In this study,the influence caused by two different types of rainfall to API was compared using Lanzhou as an example of study area.At last,the impact of sand storm on the air quality of north cities in China was identified by comparing the API of March 9 to 12,2006 and March 9 to 12,2007.