Along with the rapid industrial development and urbanization in the past decades, China has suffered from severe air pollution (Hao & Wang, 2005;Lu et al., 2020;Zhang et al., 2016). Air pollution was a threat to public health and well associated with increased risks of cardiovascular diseases and respiratory diseases (Pui et al., 2014;Sharma et al., 2020). PM 2.5 was the leading health-risk factor for attributable mortality across China (Xue, Liu et al., 2019). Liang et al. (2020) estimated the PM 2.5 -related deaths in China from 2000 to 2016 reached 30.8 million. Besides, the excessive exposure of other gaseous pollutants such as NO 2 and O 3 also aggravated health risk. Liu et al. (2018) estimated that the mortality of chronic obstructive pulmonary disease (COPD) due to overproof ozone exposure in China in 2015 reached 80,280 cases. Fortunately, Chinese government has imposed strict emission control measures including the Clean Air Action Plan (CAAP;2013 and the Blue-Sky Protection Campaign (BSPC; 2018-2020) to alleviate the PM 2.5 and O 3 pollution coordinately (Dong et al., 2022;Liu et al., 2022). However, the impact of these emission control measures on air quality improvement in China was not very clear, which was very important for control policy formulation and implementation. Therefore, it is highly imperative to quantify the comprehensive impact of emission control measures on multiple air pollutants and health benefits across China since 2013.

Organic aerosols make up the significant fraction (20%-90%) of tropospheric aerosols. They could alter the water solubility or hygroscopic properties of aerosols and serve as cloud condensation nuclei (CCN) or ice nuclei, thereby influencing the radiative forcing of the atmosphere and climate change (

Abstract. Atmospheric trace metals entail significant damages in human health and ecosystem safety, and thus a series of clean air actions have been implemented to decrease the ambient element concentrations. Unfortunately, the impact of these emission control measures on element concentrations in fine particles remains poorly understood. In our study, the random forest (RF) model was applied to distinguish the effects of emission and meteorology to trace elements in PM2.5 in a typical industrial city named Tangshan based on a 3-year (2017–2020) hourly field observation. The result suggested that the clean air actions have facilitated the dramatic decreases of the deweathered concentrations of Ga, Co, Pb, Zn, and As by 72 %, 67 %, 62 %, 59 %, and 54 %, respectively. It is attributable to the strict implementation of “coal to gas” strategies and optimisation of industrial structure and layout. However, the deweathered levels of Ca (8.3 %), Cr (18.5 %), and Fe (23 %) only displayed minor decreases, indicating that the emission control measures for ferrous metal smelting and vehicle emission were not very effective. The positive matrix factorisation (PMF) results suggested that the contribution ratios of biomass burning, non-ferrous metal smelting, coal combustion, ferrous metal smelting, heavy oil combustion, and traffic-related dust changed from 33 %, 11 %, 15 %, 13 %, 3 %, and 25 % to 33 %, 8 %, 8 %, 13 %, 4 %, and 33 %, respectively. To date, no significant non-carcinogenic and carcinogenic risks were observed for all of the elements, while both of As and Pb still showed relatively high health damages. It was proposed to further cut down the combustion-related emissions (e.g. As and Pb) because it showed the highest marginal health benefits. Besides this, the control of traffic-related emissions might be a key abatement strategy to facilitate the reduction of elements in fine particles.