中文摘要：

乌鲁木齐市冬季大气污染严重，NO2日均浓度不断增加，且超标频率增多，已成为不容忽视的环境问题。2012年乌鲁木齐市实施“煤改气”工程，旨在改善乌鲁木齐市的大气环境质量。工程的实施是否对NO2日均浓度的控制起到作用？文章选用冬李污染最为严重的时段（1-2月），对“煤改气”前后城市不同区域的NO2日均浓度变化进行了兮析。结果显示，”煤改气”后NO2日均浓度并未降低，反而呈增加的趋势，但涨幅度在区域间存在差异，主要与快速增加的机动车保有量排放大量尾气有关。“煤改气”后，冬季NO2日均浓度在空间上呈现出由南向北逐渐降低的态势，南面NO2日均浓度超标达标最严重，而北面NO2目均浓度超标频率变动不大降低，但超标频率依然较高，值得当地政府在环境治理过程中关注。

英文摘要：

Air pollution of Urumqi is very serious in winter. In past decades, the concentration of NO2 increased rapidly, which has become an environmental problem that can not be ignored. In order to improve the serious air pollution in winter, the local government has implemented the ＂Coal to Gas＂ project. Whether the project played a decisive role in controlling concentration of NO2？ This paper chooses the most serious pollution period of winter （1-2 months）, and analyzes the change of daily average concentration of NO2 before and after ＂Coal to Gas＂ in different areas of the city. The results show that after the project, instead of decreasing, the concentration of NO2 was increasing due to the Motor Vehicle increased rapidly. From South to North, the average concentration of NO2 decreased gradually in winter. In South area, the daily average concentration of NO2 was very high, while in North area, it didn＇t make much change, which worth paying attention to the environmental management process by the local government.