Abstract
Lockdown measures have been adopted in many countries worldwide due to the onset of the COVID-19 pandemic, including in Thailand. Air quality improvements with regard to restrictions of daily movement among Bangkok people have been reported. This study explores the impact of the COVID-19 outbreak and long-range pollution on air quality in Bangkok Metropolitan, Thailand by using ground-based and satellite measurements such as MODIS and TROPOMI data. Moreover, the results project some possible future trends of air quality in Bangkok Metropolitan. The 24-hr average concentrations of PM2.5, O3, NO2, CO and SO2 were compared between the periods of Normal, Lockdown and New Normal. PM2.5 concentrations increased by 20.56% during the Normal period and decreased by –15.79% and –23.34% during the Lockdown and New Normal periods, respectively, compared to the same periods in 2017–2019. There were also significant decreasing trends in O3: –7.13% and 4.72%; and CO: –8.01% and 23.59% during the Lockdown and New Normal periods, respectively, while NO2 and SO2 concentrations showed increasing trends during the three periods. The MODIS and TROPOMI data analyses indicate the COVID-19 outbreak has had significant positive impact on surface pollution, but no impact on upper atmospheric pollution due to added pollution from long-range transport. The results also demonstrate that surface air pollution had a combination effect from biomass burning, traffic, industrial and household sources during the Lockdown period, except for SO2 concentrations, which were attributed to long-range transport pollution loading. In some cases, a negative impact of the COVID-19 lockdown on air pollution can be observed due to certain activities increasing within Bangkok Metropolitan. Additionally, the results also show that changing the lifestyle into a “new normal” for people in Bangkok after the Lockdown period has had a positive effect on air pollution.
Highlights
The world has been struggling with COVID-19 since the first case has been reported on December 31, 2019 in Wuhan, China
This study explores the impact of the COVID-19 outbreak and long-range pollution on air quality in Bangkok Metropolitan, Thailand by using ground-based and satellite measurements such as MODerate Resolution Imaging Spectroradiometer (MODIS) and Tropospheric Monitoring Instrument (TROPOMI) data
Road traffic and industrial sectors are considered to be significant sources of air pollution in Bangkok (Watcharavitoon et al, 2013), and the number of vehicles on the road have been increasing every year, which implies that PM2.5 concentrations are increasing
Summary
The world has been struggling with COVID-19 since the first case has been reported on December 31, 2019 in Wuhan, China. Lockdown measures and social distancing are being used as a pandemic action plan to prevent spreading of COVID-19. Thai government imposed a curfew from March 26, 2020 to May 31, 2020 as the COVID-19 prevention plan for the whole country. These actions immediately affected daily life of human, a switch to remote working systems (including working from home, takeout only restaurants, and online shopping and delivery) and a Aerosol and Air Quality Research | https://aaqr.org transition in schools to online learning. There are decreasing trends of NO2 (27%–30%) as well as PM10 (26%–31%), PM2.5 (23%–32%), NO2 (63%–64%), SO2, (9%–20%) and CO (25%–31%) concentrations in Southeast Asian cities such as Manila, Kuala Lumpur, and Singapore (Kanniah et al, 2020)
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