BBC Chinese recently reported that, according to the numbers that the Chinese Ministry of Environment Protection released, around 75 percent of China’s large cities did not meet the air quality standard in June. Only 19 cities met the standard. In June, for around 60 percent of the days in the capital city Beijing, the air quality was below standard and its PM2.5 pollution level suffered a year-over-year 11 percent increase. PM2.5 particles are air pollutants with a diameter of 2.5 micrometers or less, small enough to invade even the smallest airways. These particles generally come from activities that involve the burning of fossil fuels, such as traffic, smelting, and metal processing. The World Health Organization (WHO) considers a PM2.5 number below 10 to be safe. The Chinese standard is 35, which the Chinese government does not expect to meet until 2030. The Ministry of Environmental Protection also found that many cities manipulated the data in order to “meet” the standard.
Source: BBC Chinese, July 13, 2015
http://www.bbc.com/zhongwen/simp/china/2015/07/150713_china_pollution_figures