LAUSR

Abstract A significant decline with primary air pollutants has occurred in China since 2013, benefiting from the Clean Air Action. Polycyclic aromatic hydrocarbons (PAHs), as ubiquitous organic pollutants in atmosphere, could also be influenced by the Action. However, related studies are limited in China. In this study, atmospheric PAHs in Harbin from June 2014 to May 2019 were monitored to evaluate the influence of the Action. During this period, significant decreasing trends of Σ15PAHs in the atmosphere were observed. The half-lives for Σ15PAHs in the total phase, gas phase, and particle phase were 3.23 ± 0.370, 2.94 ± 0.295, and 4.27 ± 0.666 years, respectively. These half-lives are shorter than those observed in other long-term monitoring programs worldwide. Furthermore, a stepwise multiple linear regression model used for primary air pollutants was applied to quantify the meteorological contribution to the decreasing trends of atmospheric PAHs. The results indicated that 35% of the decrease could be attributable to meteorological factors. In other words, the Action implementation in Harbin was proved to be the major reason for reducing atmospheric PAHs. In summary, the results observed in the present study demonstrated the effectiveness of the Clean Air Action, not only for decreasing primary air pollutants but also for atmospheric PAHs, which provides new insights into future clean air policies in China and other countries.