The concentration of BTEX in selected urban areas of Malaysia during the COVID-19 pandemic lockdown

Nor Syamimi Sufiera Limi Hawari; Mohd Talib Latif; Haris Hafizal Abd Hamid; Teoh Hwai Leng; Murnira Othman; Anis Asma Ahmad Mohtar; Azliyana Azhari; Doreena Dominick

doi:10.1016/j.uclim.2022.101238

The concentration of BTEX in selected urban areas of Malaysia during the COVID-19 pandemic lockdown

Urban Clim. 2022 Sep:45:101238. doi: 10.1016/j.uclim.2022.101238. Epub 2022 Jul 13.

Authors

Nor Syamimi Sufiera Limi Hawari¹, Mohd Talib Latif^{1

2}, Haris Hafizal Abd Hamid¹, Teoh Hwai Leng¹, Murnira Othman³, Anis Asma Ahmad Mohtar¹, Azliyana Azhari^{4

5}, Doreena Dominick^{6

7}

Affiliations

¹ Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia.
² Department of Environmental Health, Faculty of Public Health, Universitas Airlangga, 60115 Surabaya, Indonesia.
³ Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia.
⁴ Monash Climate Change Communication Research Node, School of Arts and Social Sciences, Monash University Malaysia, 47500 Bandar Sunway, Selangor Darul Ehsan, Malaysia.
⁵ Center for Research in Development, Social and Environment, Faculty of Social Science and Humanities, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia.
⁶ Centre for Atmospheric Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
⁷ School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.

Abstract

Volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene and xylene (BTEX) are air pollutants that harm human health. This study aims to identify BTEX concentrations before the lockdown known as the Movement Control Order was imposed (BMCO), during the implementation of the Movement Control Order (MCO), and then during the Conditional Movement Control Order (CMCO). These orders were introduced during the COVID-19 pandemic in Malaysia. The study utilised data measured by the continuous monitoring of BTEX using online gas chromatography instruments located at three urban area stations. The results showed that the BTEX concentrations reduced by between -38% and -46% during the MCO compared to the BMCO period. The reduction of human mobility during the MCO and CMCO influenced the lower BTEX concentrations recorded at a station within the Kuala Lumpur area. The results of the BTEX diagnostic ratios and principal component analysis showed that the major source of BTEX, especially during the BMCO and CMCO periods, was motor vehicle emissions. Further investigation, using correlation analysis and polar plots, showed that the BTEX concentrations were also influenced by meteorological variables such as wind speed, air temperature and relative humidity.

Keywords: BTEX; COVID-19; Motor vehicle; Movement control order.