4月全国地级及以上城市平均空气质量优良天数比例为83.1%

Group 1 - The average proportion of days with good air quality in 339 cities in China was 83.1% in April, a year-on-year decrease of 6.7 percentage points [1] - From January to April, there were 2060 days of sandstorm exceedance, an increase of 497 days compared to the previous year [1] - The main reasons for the increased sandstorm frequency include reduced precipitation, higher temperatures, and strong winds [1] Group 2 - The average concentration of PM10 in April was 56 micrograms per cubic meter, a year-on-year increase of 5.7% [1] - The proportion of days with severe pollution was 2.1% in April, an increase of 0.9 percentage points year-on-year [1] - It is expected that after June, the risk of sandstorms will significantly decrease due to increased rainfall and vegetation growth [2]