All seven cities saw an increase in air pollution during January-May. Readings assessed showed an average concentration of hazardous airborne particles - known as PM2.5 - up by as much as 14.8% in Taiyuan, the provincial capital, and by 16.3% in Shuozhou.[…] According to the latest data, average rates of PM2.5 in 337 cities nationwide stood at 44 micrograms per cubic meter in the first five months of the year, unchanged from 2018, with 118 cities reaching the national standard of 35 micrograms or below.
Source: wiktionary