Abstract
Particulate polycyclic aromatic hydrocarbons (PAHs) were continuously observed at Kanazawa University Wajima Air Monitoring Station (KUWAMS), a background site located in western Japan and downwind of mainland China that is constantly under the influence of polluted air masses originating from China. The observations showed that the concentration of particulate PAHs at KUWAMS sharply dropped to the lowest level (62 pg m–3) of the cold season in the last 5 years after the implementation of COVID-19 control measures in China. Despite the occasional dilution with clean air, the decrease in PAHs at KUWAMS reflected the reduction in emission intensity in China. Moreover, the PAH concentrations at KUWAMS in February, March, and April of 2020 compared with the same period in the previous year decreased by 52.6%, 36.6%, and 36.7%, respectively. These changes were consistent with the decline in SO2 and NO2 in northern China, which intensified during the control of COVID-19 and was slightly moderated after the resumption of work. In addition, there was little change in the composition of PAHs at KUWAMS before and during the COVID-19 outbreak and compared with previous years, which suggests a stable source composition. These findings emphasize the importance of decreased emission intensity in China for reducing long-range transport of PAHs and pollution levels in downwind areas.
Highlights
Polycyclic aromatic hydrocarbons (PAHs) are an important component of atmospheric particulates that influence the hormonal impact of particulates and their carcinogenic and mutagenic potential (Durant et al, 1996; Zhang et al, 2016)
Based on the concentration profile, the decrease in TSP and polycyclic aromatic hydrocarbons (PAHs) at Kanazawa University Wajima Air Monitoring Station (KUWAMS) before the COVID-19 outbreak was related to the implementation of stringent air pollution control measures in China
In the week overlapping with the Chinese Spring Festival, the PAH concentration at KUWAMS dropped to the lowest level of the cold seasons between 2015 and 2020
Summary
Polycyclic aromatic hydrocarbons (PAHs) are an important component of atmospheric particulates that influence the hormonal impact of particulates and their carcinogenic and mutagenic potential (Durant et al, 1996; Zhang et al, 2016). PAHs undergo gas-particle partitioning, transportation, conversion, and dry and wet deposition into the local environment of the receptor domain (Cheruiyot et al, 2015). Compared with low-molecular-weight PAHs, high-molecular-weight PAHs that with higher toxic potential tend to bind particles, especially those with fine size (Sheu et al, 1996; Lee et al, 2002; Lin et al, 2008). The physical and chemical behavior of PAHs during transport may lead to the loss of PAHs in particles, the enhanced health risks caused by PAHs transported to the recipient site cannot be ignored (Lee et al, 1995; Sheu et al, 1997; Zhang et al, 2020e)
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