Tian Shao’s research while affiliated with Fudan University and other places

the Chinese Government implemented "Clean Air Action" Phase I (2013-2017) and Phase II (2018-2020) consecutively to improve air quality. However, it remains unclear how these policies have impacted air quality since most studies merely focus on Phase I. In this study, we applied the Community Multiscale Air Quality (CMAQ) model to investigate variations of air quality in China during "Clean Air Action" Phases I and Phase II (2013-2020). Results show that PM 2.5 is significantly reduced (-40%) across China except in summer. O 3 concentration also decreases, but a 3% increase is found in the Beijing-Tianjin-Hebei (BTH) region. Emission changes play a dominant role in the reduction of PM 2.5 (over 95%). The contributions from meteorology and emissions to O 3 reduction are 46% and 54%, respectively. Our results suggest that a more effective emission abatement strategy should be formulated, aiming to control O 3 and PM 2.5 synergistically.

To improve air quality, China formulated the Air Pollution Prevention and Control Action Plan (APPCAP) in 2013. In the present study, the changes in the concentration of air pollutants after the implementation of APPCAP were investigated based on nationwide monitoring data. From the results, it is evident that the annual mean concentrations of PM2.5, PM10, SO2, and CO show a significant downward trend over 2015-2018, with decreasing rates of 3.4, 4.1, 3.8, and 70 μg·m⁻³/year, respectively. However, no significant change was found in NO2 while maximum daily 8h average O3 concentration (MDA8 O3) was increased by 3.4 μg·m⁻³/year during the four years. Spatially, the highest decrease in PM2.5 was found in Beijing-Tianjin-Hebei (BTH), followed by central China and northeast China, while the Pearl River Delta (PRD), Yungui Plateau, and northwest China showed less decreases. MDA8 O3 had a higher increase in BTH, central China, Yangtze River Delta (YRD), and PRD. With the decrease in PM2.5 in recent years, cumulative population exposure to PM2.5 gradually decreased, whereas there was still more than 65% of the population exposing to annual PM2.5 higher than the standard of 35 μg·m⁻³ in 2018. In contrast, the health effects of O3 gradually increased with 13.1%, 14.3%, 20.4%, and 21.7% of the population exposed to unhealthy O3 levels in summer from 2015 to 2018. O3 pollution is causing severe health risks with estimated nationwide mortality of 70,024 (95% CI: 55,510-84,501), 79,159 (95% CI: 62,750-95,525), 105,150 (95% CI: 83,378-126,852), and 104,404 (95% CI: 82,784-125,956) in the four years, respectively. This clearly shows that the target of air pollution control in China shifts and coordinated control of PM2.5 and O3 is urgently needed after the successful implementation of APPCAP.