North air quality reports in five cities: Beijing pollution year-round | |PM2.5| air quality of air pollution _ news
Haze of the pedestrian

In recent years, China′s air pollution became issues of public concern, "PM2.5" concept has been known by the public. You want to know the extent of PM2.5 pollution, without reliable data, at Peking University′s Guanghua School of management, Song Chen mountains group, and statistical sciences, Peking University Center has released the air quality assessment report (ii): statistical analysis of five urban air pollution in China.

The scope of the group selected in Beijing, Shanghai, Guangzhou, Chengdu, Shenyang, the five cities, and their use of local United States Consulate and adjacent data from two sites the Department of environmental protection. The five cities are located in Beijing, Tianjin and Hebei, Yangtze River Delta, Pearl River Delta and Sichuan and Chongqing and Liaoning economic zone, is a more serious air pollution and smog disaster area, more representative.

Data show that in these five cities, and the cities of Beijing, Chengdu′s air pollution is the most serious. Report noted that if the average duration of contamination and accounted for as an indicator of pollution severity assessment, Chengdu′s air pollution is the most serious if "serious pollution" ratio as an index of time, Beijing is the worst.

In addition, the Chengdu "good air" ratio among the five lowest in the city. Even though the air quality in Guangzhou and Shanghai, "good air" the proportion was less than 37%, and the average duration of contamination in two days or so.

Reports also show that seasonal variations in the five cities ′ air quality. In addition to Beijing and four other cities the worst air quality is best in summer and winter, and Beijing remains "year-round" summer air quality reduction was most pronounced in winter "serious pollution" and "good air" polarization. In contrast, Chengdu′s air quality in winter and summer contrast Max.

Among them, Beijing and Shenyang in winter cities of poor air quality because it has central heating during the winter months, caused by the burning of coal and other fossil fuels emissions compared with other seasons have achieved significant growth.

Worth noting is, Chengdu and Shanghai also had significant effect in winter, also has the highest PM2.5 concentrations in the winter. For example, Shanghai November 2013 and December′s increase was very large, suggesting the pollution status of Shanghai in the winter can become very serious. Similar phenomena also occurred in Guangzhou, although relatively less.

Throughout the distribution scale, Shanghai and Guangzhou "good air" and "light pollution" are more about 80%, followed by Chengdu and Shenyang, about 60% Beijing the worst, only 50%.

If comparing the concentrations of PM2.5 in the five cities, Beijing is the five cities with the worst air quality in the city, similar to the pollution degree of Shenyang, Chengdu, ranked second and third, respectively, in Guangzhou and Shanghai, the best. PM2.5 concentrations are lowest among five cities of Guangzhou, Shanghai inferior to Guangzhou due to the extreme pollution in Shanghai is much higher than Guangzhou.

However, the report also points out that from 2014, the five have reduced air pollution in big cities. In particular, the five cities the pollution is most serious in 2013. From 2013, improved pollution levels in 2014, 2015 and further improvements.

Report finds that five urban PM2.5 levels are much higher than the maximum recommended by the World Health Organization, suggested that the city, the region should be based on the local geographical conditions and characteristics of meteorological conditions to determine bearing capacity limit emissions of environmental pollutants in a jurisdiction, and in future urban planning and economic development, in strict compliance with this limit.

Responsible editor: Wang Hao

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Air pollution PM2.5 air quality in the city
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北大五城空气质量报告：北京污染全年无休|空气污染|pm2.5|空气质量_新闻资讯
雾霾中的行人

　　近年来，中国的空气污染情况成为民众关心的问题，“PM2.5”等概念也逐渐被大众所熟识。要知道PM2.5污染的严重程度，就离不开可靠的数据，北京大学光华管理学院和北京大学统计科学中心陈松蹊课题组近日发布了《空气质量评估报告（二）：中国五城市空气污染状况之统计学分析》。

　　该课题组的研究范围选取了北京、上海、广州、成都、沈阳这五个城市，并各自选用了当地美国领事馆和邻近两个环保部站点的数据。这五个城市分别位于京津冀、长三角、珠三角、川渝和辽宁经济区，是大气污染和雾霾天气灾害较为严重的区域，较具有代表性。

　　数据显示，在这五个城市中，成都和北京两个城市的空气污染情况最为严重。报告指出，如果把污染平均持续时间和占比作为污染严重程度的评价指标，成都的空气污染情况是最严重的；如果以“严重污染”时间占比作为评价指标，北京是最差的。

　　此外，成都的“优良空气”比例在五个城市中最低。即使空气质量较好的广州和上海，“优良空气”所占比例也不超过37%，而且污染状态的平均持续时间也在两天左右。

　　报告还显示，五个城市的空气质量存在季节性差异。除北京以外，其他四个城市的空气质量都是夏季最好、冬季最差，而北京保持“全年无休”，夏天空气质量减轻得最不明显，冬季则呈现“严重污染”与“优良空气”的两极分化。与之相反，成都的空气质量在冬夏季反差最大。

　　其中，北京和沈阳冬季空气质量差是因为这两个城市在冬季有集中供暖，煤炭等化石燃料的燃烧引起的污染物排放较其它季节有显著的增长。

　　值得注意的是，成都和上海也有比较明显的冬季效应，PM2.5浓度在冬季也是最高的。例如，上海2013年11月和12月的浓度增长是非常大的，这表明上海的污染状况在冬季也可能变得很严重。相似的现象也发生在广州，虽然程度相对轻一些。

　　从全年分布比例来看，上海和广州的“优良空气”和“轻度污染”较多，占80%左右；其次是成都和沈阳，占60%左右；北京最差，只有50%。

　　若将这五个城市的PM2.5浓度进行对比，北京是五个城市中空气质量最差的城市，沈阳、成都的污染严重程度相似，分别位列第二和第三，广州和上海最好。广州的PM2.5浓度是五城市中最低的，上海逊色于广州的原因是由于上海的极端污染程度要比广州高得多。

　　不过，报告也指出，从2014年开始，五大城市的空气污染情况均有所降低。具体而言，五个城市的污染在2013年都是最严重的。与2013年相比，2014年的污染程度有所改善，2015年又有进一步的改善。

　　报告认为，五城市的PM2.5水平还远远高于世界卫生组织所建议的上限，建议各城市、区域应基于当地地理条件限制和气象条件的特点，确定所辖范围内环境污染物排放的承载上限，并在今后的城市区域规划和经济发展中严格遵守这一上限。

责任编辑：王浩成

文章关键词：
空气污染 pm2.5 空气质量 城市
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