Abstract
COVID-19 has a tremendous impact on both human life and the environment due to the unprecedented large-scale shutdown of economic activities at the beginning of 2020. While it was widely expected to see a dramatic reduction in air pollution, reality appears to be much more complex due to the joint influences of emissions and meteorology in dictating air pollution. By analyzing ample meteorological and environmental observational data, this study attempts to evaluate the contribution of an economic lockdown or at a well-below normal level across China to air pollution during the COVID-19 pandemic in the Beijing-Tianjin-Hebei region. Besides the unprecedented emission reductions that helped to improve air quality, multiple other factors came into play, such as high humidity and low wind speed that are favorable for haze formation. After separating long-term trends, seasonal signals, holiday effects, and meteorological contributions concerning climatology, we estimated that the relative contributions of human activities to changes in particulate matter with a diameter of less than 2.5 μm and nitrogen dioxide during the epidemic were −17.13 μg/m3 and −0.03 μg/m3, respectively, with negative quantities denoting reductions to air pollution. Furthermore, comparing the changes in PM2.5 and NO2 concentrations after lockdown revealed that for short-term control measures, meteorological factors mainly affected pollutant particles.
Highlights
COVID-19 has been the most detrimental public crisis affecting mankind far in the twenty-first century
PBL height (PBLH) and sea-level pressure (SLP) were both measured at 1,400 h, Beijing time (BJT UTC +8 h) because the strong turbulent mixing, which occurs at noontime, best represents daily atmospheric mixing patterns (Su et al, 2020a; Shi and Brasseur, 2020)
Is this change solely related to the economic slowdown? Here, we mainly focus on the BTH region, which experiences high aerosol loading
Summary
COVID-19 has been the most detrimental public crisis affecting mankind far in the twenty-first century. There have been several studies on the impact of some major social events in China during which strict emission control measures were enforced, such as during the Beijing Summer Olympics, the Asia-Pacific Economic Cooperation, and the China Victory Day Parade (Witte et al, 2009; Wang et al, 2010; Huang et al, 2015) As natural experiments, these studies reinforced the impact of meteorology on air quality (Wang et al, 2009; Zhang et al, 2012; Liang et al, 2017). Sun et al (2020) further found that the reduction in primary aerosols was higher than that of secondary aerosols at the same relative humidity (RH) level during the Lunar New Year (LNY) In these studies, the threshold of meteorological conditions was determined subjectively, and meteorological factors were analyzed individually. In Data and Methods Section, various datasets and the methods used in this study are briefly introduced
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
