In May, the average concentration of PM2.5 in 339 prefecture-level and above cities nationwide was 22 micrograms per cubic meter, down 4.3% year-on-year; the average concentration of PM10 was 45 micrograms per cubic meter, down 2.2% year-on-year; the average concentration of O3 was 161 micrograms per cubic meter, up 8.1% year-on-year; the average concentration of SO2 was 8 micrograms per cubic meter, flat year-on-year; the average concentration of NO2 was 16 micrograms /m3, down 5.9% year-on-year; the average concentration of CO was 0.7 mg/m3, flat year-on-year.

In May, the average proportion of good air quality days in 339 cities at prefecture level and above nationwide was 78.2%, a year-on-year decrease of 10.1 percentage points; the average proportion of heavily polluted days and above was 0.5%, a year-on-year decrease of 0.1 percentage points; and the average proportion of exceeding the standard days caused by sand and dust weather was 2.9%, of which the proportion of heavily polluted days was 0.5%.

Proportion of days at all levels in 339 cities at prefecture level and above nationwide in May 2024

List of the top 20 and bottom 20 cities in terms of air quality in 168 key cities in May 2024

Source: Ministry of Ecology and Environment