EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Drivers of Increasing Ozone during the Two Phases of Clean Air Actions in China

Yuxi Liu1, Guannan Geng2, Jing Cheng1, Yang Liu1, Qingyang Xiao2, Liangke Liu1, Qinren Shi2, and Qiang Zhang1
Yuxi Liu et al.
  • 1Tsinghua University, Department of Earth System Science, Beijing, China (
  • 2Tsinghua University, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Beijing, China

In response to the severe air pollution issue, the Chinese government implemented two phases (Phase I: 2013-2017, Phase II: 2018-2020) of clean air actions since 2013, resulting in a significant decline in fine particles (PM2.5) during 2013-2020, while the maximum daily 8 h average ozone (MDA8 O3) increased by 2.6 μg m-3 yr-1 during the same period. Here, we derived the drivers behind the rising O3 concentrations during the two phases of clean air actions by using a bottom-up emission inventory, a regional chemical transport model, and a multiple linear regression model. We found that both meteorological variations (3.6 μg m-3) and anthropogenic emissions (6.7 μg m-3) contributed to the growth of MDA8 O3 from 2013 to 2020, with the changes in anthropogenic emissions playing a more important role. The anthropogenic contributions to the O3 rise during 2017-2020 (1.2 μg m-3) were much lower than that in 2013-2017 (5.2 μg m-3). The lack of volatile organic compound (VOC) control and the decline in nitrogen oxides (NOX) emissions were responsible for the O3 increase in 2013-2017 due to VOC-limited regimes in most urban areas, while the synergistic control of VOC and NOX in Phase II initially worked to mitigate O3 pollution during 2018-2020, although its effectiveness was offset by the penalty of PM2.5 decline. Future mitigation efforts should pay more attention to the simultaneous control of VOC and NOX to improve O3 air quality.

How to cite: Liu, Y., Geng, G., Cheng, J., Liu, Y., Xiao, Q., Liu, L., Shi, Q., and Zhang, Q.: Drivers of Increasing Ozone during the Two Phases of Clean Air Actions in China, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5103,, 2023.