Trends in the sizes and carbonaceous fractions of primary emitted particulate matter in China from 1960 to 2019.

Abstract

The health impacts of particulate matter (PM) depend on its concentration, size and composition. Herein, we quantified the changes in the emissions of primary PM_2.5, PM_2.5-10 and PM_>10 with aerodynamic diameters of <2.5 μm, 2.5-10 μm and >10 μm, respectively, black carbon (BC), and organic carbon (OC) to address the changes and driving factors. The temporal trends of PM emissions follow Kuznets curves, with 1995 as the peak year when the gross domestic product per capita was only US$1023, showing a late-mover advantage. The fractions of PM_2.5 : PM_2.5-10 : PM_>10 and BC : OC : non-carbonaceous-PM_2.5 from various sectors varied following different trajectories. The mass fractions of PM_2.5 : PM_2.5-10 : PM_>10 from iron-steel production industries changed from 21% : 12% : 67% in 1960 to 50% : 13% : 37% in 2019, showing a decrease in PM size. The fractions of BC were linearly correlated with PM_2.5, whereas the dependence of OC on PM_2.5 differed before and after 1995, owing to changes in residential emissions. Various factors influencing the changes in size and carbonaceous fraction were explored. The major factors were the promotion of dust-removal capacity and the transition in residential energy from solid fuels to emission-free fuels, which increased the fractions of fine PM and carbonaceous fraction.