Indoor and Outdoor Exposure to PM2.5 during COVID-19 Lockdown in Suburban Malaysia

Peter Brimblecombe,Zulfa Hanan Asha’ari,Zamzam Tuah Ahmad Ramly,Amirul Aiman Fazil,Md Firoz Khan,Eliani Ezani,Sharifah Norkhadijah Syed Ismail

doi:10.4209/aaqr.2020.07.0476

Peter Brimblecombe, Zulfa Hanan Asha’ari + Show 5 more

Open Access

https://doi.org/10.4209/aaqr.2020.07.0476

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Abstract

During the COVID-19 pandemic, key policies aimed at reducing exposure to the virus from social distancing, restrictions on travel through to strongly enforced lockdowns. However, COVID-19 restrictions required people to spend more time at home so the exposure to air pollutants shifted to being derived from that of domestic interiors, rather than outdoors or the workplace environment. This study aims to characterise the influence of lockdown intervention on the balance of indoor and outdoor PM2.5 exposure in a Malaysian suburb. We also calculate the potential health risk from exposure to both indoor and outdoor PM2.5 to give context to personal exposure assessment in different microenvironments during the COVID-19 lockdown, known locally as Movement Control Orders (MCO). The implementation of the MCOs slightly reduced daily average of outdoor PM2.5 concentrations (median of 12.63 µg m–3 before and 11.72 µg m–3). In the Malaysian apartment considered here, cooking led to a substantial increase in exposure from increasing concentrations in PM2.5 during a COVID-19 lockdown (maximum average concentration at 52.2 µg m–3). The estimated excess risk to health was about 25% for lung cancer from staying indoor. Thus, there seems a potential for greater exposure to fine particles indoors under lockdown, so it is likely premature to suggest that more lives were saved through a reduction of outdoor pollutants than lost in the pandemic. Unfortunately, little is known about the toxicity of indoor particles and the types of exposures that result where people increase the amount of time they spend working from home or staying indoors, especially during periods of lockdown.

Highlights

During the COVID-19 pandemic lower concentrations of ambient air pollutants were observed at many areas of the world due to widespread restrictions on travel, social activities and work
Our study characterised the influence of Movement Control Orders (MCO) lockdown intervention on the balance of indoor and outdoor PM2.5 exposure and likely potential changes in the risk to health
The reduction in human movement and changed work patterns led to reduced pollutant emissions widely observed as a reduction in air pollutant concentrations

Summary

Introduction

During the COVID-19 pandemic lower concentrations of ambient air pollutants were observed at many areas of the world due to widespread restrictions on travel, social activities and work. Imposed changes to human activity led to a reduction in pollutant emissions, which was unprecedented on such a wide geographic scale This provided a unique opportunity for researchers to assess the effect of the changes on air quality as measured from data monitored from satellite to ground measurements (Abdullah et al, 2020; Chauhan and Singh, 2020; Dantas et al, 2020; Dutheil et al, 2020; Muhammad et al, 2020; Nakada and Urban, 2020; Sharma et al, 2020; Tobías et al, 2020; Wang and Su, 2020; Xu et al, 2020). The reduction of these sources during lockdown frequently improved air quality, with a notable decrease in NO2 concentrations, there have been increases in ozone concentrations e.g., across Northern China surface O3 concentrations rose during the epidemic (Huang et al, 2020b; Shi and Brasseur, 2020), with large increases in urban Beijing and Wuhan and more modest changes in Shanghai and Guangzhou (Zhao et al, 2020)

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