Particulate matter pollution in Chinese cities: Areal-temporal variations and their relationships with meteorological conditions (2015-2017).

As the second largest economy in the world, China experiences severe particulate matter (PM) pollution in many of its cities. Meteorological factors are critical in determining both areal and temporal variations in PM pollution levels; understanding these factors and their interactions is critical for accurate forecasting, comprehensive analysis, and effective reduction of this pollution. This study analyzed areal and temporal variations in concentrations of PM, PM, and PM (PM - PM) and PM to PM ratios (PM/PM) and their relationships with meteorological conditions in 366 Chinese cities from January 1, 2015 to December 31, 2017. On the national scale, PM and PM decreased from 48 to 42 μg m³ and from 88 to 84 μg m³, respectively, and the annual mean concentrations were 45 μg m³ (PM) and 84 μg m³ (PM) during the time period (2015-2017). In most regions, largest PM concentrations occurred in winter. However, in northern China, in spring PM concentrations were highest due to dust. The PM/PM ratio was higher in southern than in northern China. There were large regional disparities in PM diurnal variations. Generally, PM concentrations were negatively correlated with precipitation, relative humidity, air temperature, and wind speed, but were positively correlated with surface pressure. The sunshine duration showed negative and positive impacts on PM in northern and southern cities, respectively. Meteorological factors impacted particulates of different size differently in different regions and over different periods of time.