Impact of National Movement Control Orders toward Ground Level Ozone Concentrations in Shah Alam

Abstract

Malaysia is currently facing the COVID-19 pandemic which has claimed hundreds of innocent lives. Because of the health problems impose by the pandemic, the government has ordered to implement the movement control order (MCO) starting March 18, 2020. With this movement control order in place, people are not allowed to leave the house. Therefore, movement on the road can also be reduced. This study was conducted to investigate the emission concentrations of ground-level ozone into the air during MCOs in an urbanized area of Shah Alam. This secondary data of ground-level ozone (O3) was acquired from the Department of Environment in 2020 and interpreted using the methods of box and whisker plot, time series analysis, and diurnal variation plot. The results found that the concentrations of air pollutants in each type of MCOs implemented were different in terms of trends. During the early implementations of MCOs, results showed that there was a slight decrement in O3 concentrations and as MCOs periods continued, there higher decrements in O3 concentrations were observed. During the MCOs period, non-exceedance episodes were recorded which show the level of ground-level ozone was significantly improved result of the implementation of MCOs. Results also suggested there is a shift in the peak concentration time as the plot showed peak concentrations were reached between 4 to 6 p.m. which is quite later as normally peaks O3 concentrations were reported normally reached from 12 noon to 2 p.m. [13]

Diurnal variation of secondary air pollutant concentrations during movement restriction orders in Johor

“…Meanwhile, in Malaysia, particulate matter (PM) reductions of 58.4% were first observed over the Peninsular Malaysia region during the MCO period [3]. As been reported by Awang et al [4] there are a slight decrease in O3 concentration has been recorded in Shah Alam upon implementation of MCOs. Encouraged by the finding of researchers on air pollutants, this study would like to determine the impact of the MCO on the ground level.…”

Drivers of nocturnal interactions between ground-level ozone and nitrogen dioxide

“…Conversely, NO2 displayed late afternoon peaks at 10 p.m. for both urban and suburban sites, with concentrations of 20 ppb and 12 ppb, respectively. This peak coincided with rush-hour traffic (Latif et al, 2021;Awang et al, 2022). Even though the effect of light pollution is small, still, this phenomenon has different consequences for O3 formation (AGU, 2012), where the lighting in urban sites influences NO3 photolysis as a sink for NO3 and N2O5 at night (Brown et al, 2007;Stark et al, 2010).…”

“…This is due to various anthropogenic activities which became a significant source of O3 precursors in urban areas (Ghazali et al, 2010;Latif et al, 2012;Awang et al, 2015;Shith et al, 2021;Shith et al, 2022). After the MCO, the O3 concentrations reduced significantly, indicating the reduction in motor vehicles on the road as the effect of the temporary closure of industries during the MCO 1 (Othman & Latif, 2020;Mohd Nadzir et al, 2021;Awang et al, 2022).…”