Chinese people have enjoyed blue-sky days more often than before in recent years, thanks to the Action Plan for the Prevention and Control of Air Pollution ("Action Plan") was initiated by the State Council in 2013. The “Action Plan” aims to achieve effective control of air pollutants headed by fine particles (PM2.5) in the key areas through the source emission reduction.

"Air quality in China has improved in recent years, but what are the effects of improvement? And what are our challenges in the future? My group worked with a number of research institutes home and abroad to assess and analyze the changes in the mass concentration of atmospheric particulate matter, especially its chemical compositions under the implementation of the ‘Action Plan’”, said Prof. WANG Yuesi, from State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC) at the Institute of Atmospheric Physics with Chinese Academy of Sciences.

The group studied the effects of improvement in the air quality in typical regions of China based on the data from the "CARE-China", the national scale observation network established by LAPC, and the "National air quality monitoring network" of the China National Environmental Monitoring Centre, Ministry of Ecology and Environment.

The group found that the annual PM2.5 concentration in major cities of China showed a significant decreasing trend, and the "Action Plan" target was fulfilled earlier than expected. In particular, the concentrations of sulfate and organic matter (OM) in PM2.5 decreased more than 30%, during heavy pollution in autumn and winter, in Beijing-Tianjin-Hebei, Chengdu-Chongqing, and Fenwei Plain.

"still," said Wang, "PM2.5 concentration in 64% of 74 cities did not attain the national standard in 2017. And we have a new challenge: photochemical pollution."

According to the article, photochemical pollution, represented by ozone, showed a rapid upward trend.

"It is good that the blue sky is coming back. However, surface ozone is also increasing, which is a new challenge for future air pollution control. From a scientist’s perspective, I think it is a unique opportunity to advance our current atmospheric chemistry and physics knowledge about influence of anthropogenic activity on our atmosphere." Said Wang.

For the policy makers, Wang suggested that high-strength nitrogen oxides control, all-round volatile organic compounds control, and new-addition ammonia (including ammonia and ammonium salts) as China's major pollutant monitoring list should be the further control direction of the overall long-term standard of air quality in China.

On the basis of this research, a series of papers on the effectiveness and new challenges of air pollution control in China were published in National Science Review & Chinese Science: Earth Science by Prof. Wang's Group.

These researches were supported by the strategic pilot project of the Chinese Academy of Sciences, the national key R & D program of the Ministry of Science and Technology, the major projects on the causes and treatment of atmospheric heavy pollution (" Prime Minister's Project "), the National Natural Science Foundation of China and the Beijing Municipal Science and Technology Commission.

(1) Wang Yuesi, Li Wenjie, Gao Wenkang, Liu Zirui, Tian Shili, Shen Rongrong, Ji Dongsheng, Wang Shuai, Wang Llili, Tang Guiqian, Song Tao, Cheng Mengtian, Wang Gehui, Gong Zhengyu, Hao Jiming, Zhang Yuanhang. 2019. Trends in particulate matter and its chemical compositions in China from 2013–2017. Science China Earth Sciences, 62(12): 1857–1871.
(2) Yonghong Wang, Wenkang Gao, Shuai Wang, Tao Song,Zhengyu Gong, Dongsheng Ji,Lili Wang, Zirui Liu, Guiqian Tang,Yanfeng Huo, Shili Tian, Jiayun Li, Mingge Li,Yuan Yang, Biwu Chu, Tuukka Petaja,Veli-Matti Kerminen,Hong He,Jiming Hao,Markku Kulmala, Yuesi Wang*, Yuanhang Zhang*. 2020. Contrasting trends of PM2.5 and surface-ozone concentrations in China from 2013 to 2017. National Science Review, NSR, https://doi.org/10.1093/nsr/nwaa032