Globally analysing spatiotemporal trends of anthropogenic PM2.5 concentration and population's PM2.5 exposure from 1998 to 2016

Abstract

Air pollution in the form of particulate matter (PM) is becoming one of the greatest current threats to human health on a global scale. This paper firstly presents a Bayesian space-time hierarch piecewise regression model (BSTHPRM) which can self-adaptively detect the transitions of local trends, accounting for spatial correlations. The spatiotemporal trends of the approximately anthropogenic PM_2.5 removed natural dust (PM_{2.5_No Dust}) concentrations and the corresponding population's PM_{2.5_No Dust} exposure (PPM_2.5E) in the global continent from 1998 to 2016 were investigated by the presented BSTHPRM. The total areas of the high and higher PM_{2.5_No Dust}-polluted regions, whose spatial relative magnitude of PM_{2.5_NoDust} pollution to the global continental overall level was between 1.89 and 14.68, accounted for about 13.4% of the global land area, and the corresponding exposed populations accounted for 56.0% of the global total population. The spatial heterogeneity of the global PM_{2.5_NoDust} pollution increased generally from 1998 to 2016. The areas of hot, warm, and cold spots with increasing trends of PM_{2.5_NoDust} concentration initially contracted and then later expanded. The local trends of the global continental PM_{2.5_NoDust} concentrations and PPM_2.5E can be parted into three changing stages, early, medium, and later stages, using the BSTHPRM. The area proportions of the regions experiencing a decreasing trend of PM_{2.5_NoDust} concentrations and PPM_2.5E were greater in the medium stage than in the early and later stages. The local trends of PM_{2.5_NoDust} concentration and PPM_2.5E in the two higher PM_{2.5_NoDust} polluted areas, northern India and eastern and southern China, increased in the early stage and then decreased in the medium stage. In the later stage (recent years), northern India displayed a stronger increasing trend; nevertheless, the follow-up decreasing trend still occurred in eastern and southern China. In the first two stages, more than half of the areas in Europe experienced a decreasing trend of PM_{2.5_NoDust} concentration and PPM_2.5E; later, more than half of areas in Europe exhibited increasing trends in the later stage. North America and South America experienced a similar local trend of PPM_2.5E to Europe. The PPM_2.5E trend in Africa generally increased during the study period.

Keywords: Bayesian statistics; Global PM(2.5) pollution; Population's PM(2.5) exposure; Spatiotemporal trends.