Air quality in China. China has long been criticized for its air pollution. According to the Word Bank’s statistics, China’s population was the highest in the world (1,364,270,000) in 2014, followed by India (1,295,292,000) and the United States (318,857,000). There is a large population exposed to high levels of PM as well as O3 in the ambient air that does not meet either the Chinese ambient air quality standard (GB 3095-1996) or the World Health Organization Air Quality Guidelines (Table 1) (Ministry of Environmental Protection of People's Republic of China, 1996; WHO 2005; Zhang et al., 2010). In a recent report by GreenPeace, the annual mean PM2.5 concentrations in total 366 cities in China were 50.2 μg/m3 in 2015 with the highest annual mean of 80.7 μg/m3 in Henan, and lowest annual mean of 10.6 μg/m3 in Tibet (GreenPeace, 2016). China Daily also reported 9.6% higher PM2.5 concentrations in 2015 in the North China compared to the previous winter when people used more heating (China Daily, 2016). This article also pointed out that 8-hour daily average O3 concentrations in 2015 was 3.4% and 7.9% higher compared to the years 2013 and 2014, respectively (China Daily, 2016). Because of an increasing awareness of air pollution by the public since the 2008 Olympic Games and the 2010 World Expo, a new draft of criteria pollutant standards came out in 2012 and took effect in January, 2016. This new draft added annual and 24-hour mean PM2.5 concentrations in the NAAQS (GB 3095-2012) (Table 1). The new standard also required all the counties in the nation to report their daily air quality. To test this policy, several key regions, including Beijing-Tianjin-Hebei, the Yangtze River Delta, the Pearl River Delta, and provincial capitals were required to publicize air quality data since 2012. Based on the data published on the Chinese Environmental Protection Bureau website, it is clear that most of the big cities will fail to meet the new PM2.5 standard (MEP, 2016). Chan and Yao (2008) analyzed air pollution in multiple urban cities in China and they concluded that PM pollution was severe, as well as secondary pollution (such as O3). Cao et al. (2011) conducted the first epidemiological cohort study focusing on air pollution and mortality in China at the national level. They studied total suspended particles (TSP), sulfur dioxide (SO2) and nitrogen oxides (NOx), and found a 0.9% increase for all-cause mortality with 10 μg/m3 increase in TSP, a 1.8% increase for mortality with 10 μg/m3 ...
