Atmospheric environment

Basic state

In 2019, out of all the 337 cities at and above prefecture-level (APL cities) (hereinafter referred to as the 337 cities) across the country, 157 cities met national air quality standard, accounting for 46.6 percecnt of the total; 180 cities failed to meet national air quality standard, taking up 53.4 percent.

In 2019, the average percentage of days of the 337 cities meeting air quality standard was 82.0 percent. In specific, the attainment rate reached 100 percent for 16 cities, stood between 80-100 percent for 199 cities, 50-80 percent for 106 cities and less than 50 percent for 16 cities. The ratio of average number of days failing to meet the standard** took up 18.0 percent, among which, the number of days with PM2.5, O3, PM10, NO2 and CO as the primary pollutant took up 45.0 percent, 41.7 percent, 12.8 percent, 0.7 percent and less than 0.1 percent respectively. There was no occurrence of nonattainment days with SO2 as the primary pollutant.

In 337 cities, 452 days were under very heavy pollution, 183 days less than that of 2018; 1,666 days were under heavy pollution, 88 days more than that of 2018. Among them, days with PM2.5, PM10 and O3 as the primary pollutant took up 78.8 percent, 19.8 percent and 2.0 percent respectively. There was no occurrence of heavy or very heavy pollution with SO2, NO2 and CO as the primary pollutant.

Problems

• Straw burning

In 2019, satellite remote sensing monitored a total of 6,300 straw burning sites in the country (excluding burning site information under cloud cover), mainly distributed in Heilongjiang, Inner Mongolia, Jilin, Hebei, Shanxi, Liaoning, Anhui, Shandong, Hubei and Henan province (region). The number of burning sites was 1,347 fewer than that in 2018.

• Acid rain

Acid rain distribution In 2019, the total area covered by acid rain was about 474,000 km², taking up 5.0 percent of total land area of China, down by 0.5 percentage point compared with that of 2018. Among them, the percentage of land area with relatively serious acid rain was 0.7 percent*. Acid rain was mainly distributed in the region south to the Yangtze River and east to Yunnan-Guizhou Plateau, mainly including Zhejiang, most of Shanghai, northern part of Fujian, central part of Jiangxi, central and eastern part of Hunan, central part of Guangdong and southern part of Chongqing.

Acid rain frequency In 2019, the average acid rain frequency of 469 cities (districts or counties) under precipitation monitoring was 10.2 percent, down by 0.3 percentage point compared with that of 2018. The rate of cities with acid rain occurrence was 33.3 percent, down by 4.3 percentage points compared with that of 2018. The percentage of cities with acid rain frequency over 25 percent, 50 percent and 75 percent was 15.4 percent, 8.3 percent and 2.6 percent respectively.

Precipitation acidity In 2019, the annual average pH value of precipitation across the country ranged from 4.22 (Ji'an of Jiangxi province) to 8.56 (Korla of Xinjiang autonomous region) with the average value of 5.58. The rate of cities with acid rain, relatively serious acid rain and serious acid rain was 16.8 percent, 4.5 percent and 0.4 percent respectively.

*The acid rain is defined when the precipitation pH value is below 5.6; relatively serious acid rain is defined when the pH value is below 5.0; serious acid rain is defined when the pH value is below 4.5.