Proof of effect from Clean Air Actions on atmospheric alkylated polycyclic aromatic hydrocarbons

Clean Air Actions were implemented in China in 2013 to reduce air pollutants in the atmosphere through stringent emission controls. Alkylated polycyclic aromatic hydrocarbons (Alk-PAHs), which are derivatives of polycyclic aromatic hydrocarbons, are highly toxic, and their levels have been affected after the implementation. This study-conducted in Harbin, a northeastern Chinese city-investigated the policy's impact by analyzing temporal variations in the concentrations of gaseous and particulate Alk-PAHs from 2014 to 2019. The major air-pollutant data were obtained from the China National Environmental Monitoring Center Network. The measured concentrations of Alk-PAHs in the atmosphere exhibited a significant decreasing trend, with a halving time of 2.67 ± 0.63 years. Meanwhile, the cancer risk (CR) associated with inhalation and dermal exposure demonstrated a halving time of 1.80 ± 0.49 years. Despite the declining trends in the CR associated with inhalation and dermal exposure across three age groups (children, adolescents, and adults), adolescents showed a potential CR. Furthermore, by differentiating the effects of meteorological factors and anthropogenic emission control measures on the decreasing concentrations of ∑₃₀Alk-PAHs and total benz[a]pyrene equivalent concentration (∑BaP_eq), 64 % of the reduction in the concentration of ∑₃₀Alk-PAHs and 87 % of the decline in ∑BaP_eq was attributed to anthropogenic emission control measures. Therefore, we can deduce that the implementation of Clean Air Actions not only decreased the concentrations of primary air pollutants, such as PM_2.5 particles, PM₁₀ particles, sulfur dioxide, nitrogen oxides, and carbon monoxide but also decreased the concentration of atmospheric Alk-PAHs.