The characteristics and drivers of fine particulate matter (PM2.5) distribution in China

Abstract

The frequent occurrence of extreme haze episodes in China in recent years has triggered the Chinese government to take action to tackle the serious air quality problems. Fine particulate matter (PM<inf>2.5</inf>) accounts for much of China's poor air quality; given the health risks associated with such pollution, the spatiotemporal characteristics of urban PM<inf>2.5</inf> concentrations constitute a matter of significant interest within the Chinese research and policy communities. Using the first long-term datasets available in relation to PM<inf>2.5</inf> levels, obtained from a year-long monitoring program of concentrations utilizing 945 monitoring stations in 190 cities in China in 2014, we found significant differences in PM<inf>2.5</inf> concentrations among cities, ranging between 18.7 and 131.4 μg/m³, with an average of at 61 ± 20 μg/m³; only 18 (or 9.5%) of the 190 monitored cities could meet the National Ambient Air Quality Standards of China. PM<inf>2.5</inf> concentrations are generally highest in the cities east of the Hu Line and north of the Yangtze River due to high PM emissions from transport and coal combustion and unfavorable atmospheric conditions. We also observed marked seasonal variations in concentration levels, with the highest levels occurring during winter and the lowest in summer. By grouping Chinese cities according to their size, our econometric analysis shows a positive correlation between PM<inf>2.5</inf> concentrations and the size of the urban area, urban population, share of secondary industry and population density, and a first increasing and then decreasing relationship between GDP per capita and PM<inf>2.5</inf> concentration. Urban expansion and structural economic change has thus contributed to an increase in urban PM<inf>2.5</inf> emissions. Without careful planning, continuing urbanization will precipitate further severe air pollution causing significant health risks.