The varying driving forces of PM concentrations in Chinese cities: Insights from a geographically and temporally weighted regression model.

BACKGROUND

Particulate pollution is currently regarded as a severe environmental problem, which is intimately linked to reductions in air quality and human health, as well as global climate change.

OBJECTIVE

Accurately identifying the key factors that drive air pollution is of great significance. The temporal and spatial heterogeneity of such factors is seldom taken into account in the existing literature.

METHOD

In this study, we adopted a geographically and temporally weighted regression model (GTWR) to explore the direction and strength of the influences of natural conditions and socioeconomic issues on the occurrence of PM pollutions in 287 Chinese cities covering the period 1998 to 2015.

RESULT

Cities with serious PM pollution were discovered to mainly be situated in northern China, whilst cities with less pollution were shown to be located in southern China. Higher temperature and wind speed were found to be able to alleviate air pollution in the country's southeast, where enhanced precipitation was also shown to reduce PM concentrations; whilst in southern and central and western regions, precipitation and PM concentrations were positively correlated. Increased relative humidity was found to reinforce PM concentration in southwest and northeast China. Furthermore, per capita GDP and population density were shown to intensify PM concentrations in northwest China, inversely, they imposed a substantial adverse effect on PM concentration levels in other areas. The amount of urban built-up area was more positively associated with PM concentration levels in southeastern cities than in other cities in China.

CONCLUSION

PM concentrations conformed to a series of stages and demonstrated distinct spatial differences in China. The associations between PM concentration levels and their determinants exhibit obvious spatial heterogeneity. The findings of this paper provide detailed support for regions to formulate targeted emission mitigation policies.