Special Issue on COVID-19 Aerosol Drivers, Impacts and Mitigation (VI)

Zulfa Hanan Ash’aari1, Ahmad Zaharin Aris This email address is being protected from spambots. You need JavaScript enabled to view it.1, Eliani Ezani2, Nurfatin Izzati Ahmad Kamal1, Norlin Jaafar3, Jasrul Nizam Jahaya3, Shamsuri Abdul Manan3,  Muhamad Firdaus Umar Saifuddin1

1 Department of Environment, Faculty of Forestry and Environment, Universiti Putra Malaysia, 43400, UPM Serdang, Selangor, Malaysia
2Department of Environmental and Occupational Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
3Department of Environment, Wisma Sumber Asli, Persiaran Perdana, 62574 Federal Territory of Putrajaya, Malaysia


Received: June 21, 2020
Revised: August 8, 2020
Accepted: August 19, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.2020.06.0334  

Cite this article:

Ash’aari, Z.H., Aris, A.Z., Ezani, E., Ahmad Kamal, N.I., Jaafar, N., Jahaya, J.N., Manan, S.A. and Umar Saifuddin, M.F. (2020). Spatiotemporal Variations and Contributing Factors of Air Pollutant Concentrations in Malaysia during Movement Control Order due to Pandemic COVID-19. Aerosol Air Qual. Res. 20: 2047–2061. https://doi.org/10.4209/aaqr.2020.06.0334


  • Urban and sub-urban settings exhibit significant reduction of all major air pollutants during MCO.
  • Rural stations located in other region than central and north peninsular exhibit no change.
  • Background station shows improvement, an evidence of minimum human impact.
  • Local economic activities hence proof the impact of MCO at other settings.


The restriction of daily and economic-related activities due to COVID-19 pandemic via lockdown order has been reported to improve air quality. This study evaluated temporal and spatial variations of four major air pollutant concentrations across Malaysia before (March 4, 2020–March 17, 2020) and during the implementation of different phases of Movement Control Order (MCO) (March 18, 2020–May 12, 2020) from 65 official regulatory air quality stations. Results showed that restriction in daily and economic activities has remarkably reduced the air quality in all sub-urban, urban, and industrial settings with relatively small contributions from meteorological conditions. Overall, compared to before MCO, average concentrations of PM2.5, CO, and NO2 reduced by 23.1%, 21.74%, and 54.0%, respectively, while that of SO2 was constant. The highest reduction of PM2.5, CO, and NO2 were observed in stations located in urban setting, where 63% stations showed significant reduction (p < 0.05) for PM2.5 and CO, while all stations showed significant reduction in NO2 concentrations. It was also revealed that 70.5% stations recorded lower concentrations of PM2.5 during MCO compared to before MCO, despite that high numbers of local hotspots were observed simultaneously from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS). Spatial analysis showed that the northern part of Peninsular had the highest significant reduction of PM2.5, while the highest of NO2 and CO reduction were found in stations located in the central region. All pollutants exhibit similar diurnal trends when compared between pre- and during MCO although significant lower readings were observed during MCO. This study gives confidence to regulatory body; the enforcement of strict air pollution prevention and control policies could help in reducing pollution.

Keywords: Aerosols; Anthropogenic emissions; Area sources; Mobile sources; Stationary sources.


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Aerosol Air Qual. Res. 20 :2047 -2061 . https://doi.org/10.4209/aaqr.2020.06.0334  

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