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目的分析2014年全国31个重点城市空气质量特征,为预防大气污染提供依据。方法利用环境保护部数据中心每日发布的全国空气质量监测数据,对31个城市空气质量和首要污染物分布特征,及其空气质量等级与首要污染物关系进行分析。结果 31个城市年均空气质量指数(AQI)为83,空气污染最严重的区域是华北地区,最严重城市是石家庄市。全年空气质量以二级日数为主,而空气污染日数(AQI>100的日数)占全年的34.40%;首要污染物为PM2.5和PM10,分别占总日数的38.30%和29.50%,其中合肥市最高,达全年日数的78.00%。AQI水平在1—3月最高,其次为10—12月,4—9月相对较低且平稳;AQI等级与首要污染物分布有关,空气质量AQI水平在三到六级,以PM2.5为首要污染物所占的天数,分别占三到六级各级总天数的61.00%、83.90%、96.30%及72.30%。结论全国2014年31个城市空气质量分布呈明显区域特征,且随季节改变呈明显变化。空气污染的首要污染物以PM2.5为主,PM2.5日数比例随着空气污染等级的增加而增加。
Objective To analyze the air quality characteristics of 31 key cities in China in 2014, and provide the basis for preventing air pollution. Methods Based on the daily national air quality monitoring data released by the MEP data center, the air quality and the distribution characteristics of primary pollutants in 31 cities and the relationship between their air quality levels and primary pollutants were analyzed. Results The average annual air quality index (AQI) of 31 cities was 83, the area with the most serious air pollution was in North China, and the most serious city was in Shijiazhuang. Year-round air quality was dominated by the second-level days, while air pollution days (days with AQI> 100) accounted for 34.40% of the year. Primary pollutants were PM2.5 and PM10, accounting for 38.30% and 29.50% of the total number of days respectively, The highest in Hefei, up to 78.00% of the full-year number. The AQI level was highest in January-March, followed by October-December, relatively low and stable in April-September. The AQI level was related to the distribution of primary pollutants. The AQI level of air quality ranged from 3 to 6, The number of days that the primary pollutants account for was 61.00%, 83.90%, 96.30% and 72.30% of the total number of days at all levels three to six respectively. Conclusion The distribution of air quality in 31 cities in China showed obvious regional characteristics in 2014, and obviously changed with the seasons. The main pollutants of air pollution to PM2.5-based, PM2.5 days on the basis of evidence that the growth rate of increase.