Air quality improves with favorable weather conditions

China's air quality has improved due to favorable weather conditions last year, according to a recent meteorological bulletin of the atmospheric environment.

The bulletin, released by the China Meteorological Administration, stated that the air stagnation index, which measures factors such as wind speed and air ventilation, was 11 last year, down 3.5 percent year-on-year. Less stagnant weather means it is a good condition for the diffusion of polluting particles.

Last year, the country had an average of 20.5 days with smog, about seven days less than 2017. The coverage and occurrence frequency of smog had also decreased.

The average density of PM2.5 went down by 9.3 percent and PM10 by 5.3 percent.

Though the country's weather conditions were better last year, the air stagnation index in the Beijing-Tianjin-Hebei province cluster and the Yangtze River Delta region rose a little as compared to the average index of the previous five years, especially in the months of November and December.