[Exposure Level of Population and Economy in Zhejiang Province Considering the Background of PM2.5 in East China].

Using the satellite-derived Fine Particulate Matter (PM2.5) data of global high-precision products during 1998-2012, detailed characteristics of PM2.5 distribution over East China and its change are given, and the PM2.5 exposure levels for population and economy in Zhejiang is further analyzed in this context. The results show that the overall variability of the regional average value of PM2.5 concentration exhibits an increasing trend followed by a decrease during 1998-2012, which is consistent in both the East China and Zhejiang provinces; the turning point occurs around 2007-2009. In the initial years (1998-2000), annual average PM2.5 concentrations are below 50 µg·m-3 in the southern part of East China and eastern part of Shandong, while it is 50-75 µg·m-3 in other areas. During this period, 51.8% of the area in East China and 21.1% of the area in Zhejiang have PM2.5 concentrations larger than 35 µg·m-3 (Air quality standard value in China). The rising trend in PM2.5 concentration is extremely obvious in 1998-2009; the mean linear trend over East China is 2.58 µg·(m3·a)-1, while it is 1.43 µg·(m3·a)-1 over Zhejiang province. PM2.5 concentration reaches its maximum during 2007-2009. The area where PM2.5 concentration is larger than 35 µg·m-3 reaches 82.1% in East China and 65.9% in Zhejiang province. After that, the PM2.5 concentration begins to decrease in each region, and the average change trend in East China and Zhejiang are -1.75 µg·(m3·a)-1 and -1.58 µg·(m3·a)-1, respectively. The regional area in which PM2.5concentrations aregreater than 35 µg·m-3 displays a slight decline during 2010-2012, which suggests that the energy conservation and emission reduction plan proposed by the Chinese government and associated measures may play a vital role in improving air quality of East China. In 2010, the proportion of the population and GDP for which the PM2.5 exposure level exceeded 35 µg·m-3 were 74.0% and 70.8%, respectively, of which 38.1% of the population lives in an environment where annual average PM2.5 concentrations are more than 50 µg·m-3. In addition, 38.9% of the GDP is produced in an environment with annual average PM2.5 concentrations more than 50 µg·m-3.