With the outbreak of the COVID-19 pandemic around the world, many countries announced lockdown measures, including Thailand. Several scientific studies have reported on improvements in air quality due to the impact of these COVID-19 lockdowns. This study aims to investigate the effects of the COVID-19 lockdown and its driving influencing factors on air pollution in Greater Bangkok, Thailand, using in situ measurements. Overall, PM2.5, PM10, O₃, and CO concentrations presented a significant decreasing trend during the COVID-19 outbreak year based on three periods: the Before Lockdown, Lockdown, and After Lockdown periods, for PM2.5: −0.7%, −15.8%, and −20.7%; PM10: −4.1%, −31.7%, and −6.1%; and O₃: −0.3%, −7.1%, and −4.7%, respectively, compared to the same periods in 2019. CO concentrations, especially which had increased by 14.7% Before Lockdown, decreased by −8.0% and −23.6% during the Lockdown and After Lockdown periods, respectively. Meanwhile, SO₂ increased by 54.0%, 41.5%, and 84.6%, and NO₂ increased by 20.1%, 3.2%, and 26.6%, respectively, for the Before Lockdown, Lockdown, and After Lockdown periods. PCA indicated a significant combination effect of atmospheric mechanisms that were strongly linked to emission sources such as traffic and biomass burning. It has been demonstrated that the COVID-19 lockdown did pause some of these anthropogenic emissions, i.e., traffic and commercial and industrial activities, but not all of them. Even low traffic emissions, on their own, did not cause an absolute reduction in air pollution since there are several primary emission sources that dominate the air quality over Greater Bangkok. Finally, these findings highlight the impact of COVID-19 lockdown measures not only on air pollution levels but on their effects on air pollution characteristics, as well.

中文翻译：

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泰国大曼谷COVID-19锁定的影响及其影响因素的调查

随着全球COVID-19大流行的爆发，包括泰国在内的许多国家宣布了封锁措施。由于这些COVID-19锁定的影响，一些科学研究报告了空气质量的改善。这项研究旨在通过现场测量来调查COVID-19锁定及其对泰国大曼谷地区空气污染的驱动影响因素。总体而言，在COVID-19爆发年中，PM2.5，PM10，O ₃和CO浓度呈显着下降趋势，这基于以下三个时期：PM2.5的锁定前，锁定和锁定后三个时期：-0.7％ ，-15.8％和-20.7％；PM10：−4.1％，− 31.7％和−6.1％；和O ₃：与2019年同期相比，分别为−0.3％，− 7.1％和−4.7％。CO浓度，特别是在锁定前增加了14.7％的CO浓度，在锁定和停产期间降低了-8.0％和-23.6％。在锁定期之后。同时，SO ₂增长了54.0％，41.5％和84.6％，而NO ₂在“锁定前”，“锁定”和“锁定后”期间分别增长了20.1％，3.2％和26.6％。PCA表明，大气机制与排放源（如交通和生物质燃烧）密切相关，具有显着的组合效应。事实证明，COVID-19锁定确实使其中一些人为排放暂停了，例如交通，商业和工业活动，但不是全部。即使只有很少的交通排放，也不能完全减少空气污染，因为大曼谷地区的空气质量主要由几种主要排放源决定。最后，这些发现凸显了COVID-19封锁措施不仅对空气污染水平的影响，而且还对空气污染特征的影响。