Shen Fuzhen, Hegglin Michaela I, Luo Yuanfei, Yuan Yue, Wang Bing, Flemming Johannes, Wang Junfeng, Zhang Yunjiang, Chen Mindong, Yang Qiang, Ge Xinlei
Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, 210044 Nanjing, China.
Department of Meteorology, University of Reading, Reading, RG6 6BX UK.
NPJ Clim Atmos Sci. 2022;5(1):54. doi: 10.1038/s41612-022-00276-0. Epub 2022 Jun 30.
The COVID-19 restrictions in 2020 have led to distinct variations in NO and O concentrations in China. Here, the different drivers of anthropogenic emission changes, including the effects of the Chinese New Year (CNY), China's 2018-2020 Clean Air Plan (CAP), and the COVID-19 lockdown and their impact on NO and O are isolated by using a combined model-measurement approach. In addition, the contribution of prevailing meteorological conditions to the concentration changes was evaluated by applying a machine-learning method. The resulting impact on the multi-pollutant Health-based Air Quality Index (HAQI) is quantified. The results show that the CNY reduces NO concentrations on average by 26.7% each year, while the COVID-lockdown measures have led to an additional 11.6% reduction in 2020, and the CAP over 2018-2020 to a reduction in NO by 15.7%. On the other hand, meteorological conditions from 23 January to March 7, 2020 led to increase in NO of 7.8%. Neglecting the CAP and meteorological drivers thus leads to an overestimate and underestimate of the effect of the COVID-lockdown on NO reductions, respectively. For O the opposite behavior is found, with changes of +23.3%, +21.0%, +4.9%, and -0.9% for CNY, COVID-lockdown, CAP, and meteorology effects, respectively. The total effects of these drivers show a drastic reduction in multi-air pollutant-related health risk across China, with meteorology affecting particularly the Northeast of China adversely. Importantly, the CAP's contribution highlights the effectiveness of the Chinese government's air-quality regulations on NO reduction.
2020年的新冠疫情防控措施导致中国的氮氧化物（NO）和臭氧（O）浓度出现显著变化。在此，通过综合模型测量方法，分离出人为排放变化的不同驱动因素，包括中国春节（CNY）、中国2018 - 2020年清洁空气计划（CAP）以及新冠疫情封锁措施及其对NO和O的影响。此外，应用机器学习方法评估了主要气象条件对浓度变化的贡献。对基于健康的多污染物空气质量指数（HAQI）的影响进行了量化。结果表明，春节平均每年使NO浓度降低26.7%，而2020年的新冠疫情封锁措施使NO浓度额外降低了11.6%，2018 - 2020年的清洁空气计划使NO浓度降低了15.7%。另一方面，2020年1月23日至3月7日的气象条件使NO浓度增加了7.8%。因此，忽略清洁空气计划和气象驱动因素分别导致对新冠疫情封锁措施对NO减排效果的高估和低估。对于O，发现情况相反，春节、新冠疫情封锁、清洁空气计划和气象影响分别导致O浓度变化为+23.3%、+21.0%、+4.9%和 -0.9%。这些驱动因素的总体影响表明中国与多种空气污染物相关的健康风险大幅降低，其中气象条件对中国东北地区产生了特别不利的影响。重要的是，清洁空气计划的贡献凸显了中国政府空气质量法规在减少NO方面的有效性。
