Changes in Air Quality during the COVID-19 Lockdown in Singapore and Associations with Human Mobility Trends

Abstract

On the 7 th of April, the Singaporean government enforced strict lockdown measures with the aim of reducing the transmission chain of the coronavirus disease 2019. This had a significant impact on the movement of people within the country. Our study aims to quantify the impact that these measures had on outdoor air pollution levels. We obtained air quality and weather data from April 2016 to May 2020, satellite data for 2019 and 2020 and mobility data for 2020 from Apple, Google, and the Singaporean Housing & Development Board. We determined that outdoor air pollution during the lockdown significantly decreased when compared with the same period in the previous four years even if we included corrections for long time trends in the analysis. The concentrations of the following pollutants PM 10 , PM 2.5 , NO 2 , CO, and SO 2 decreased by 23, 29, 54, 6, and 52%, respectively, whilst that of O 3 increased by 18%. The Pollutant Standard Index decreased by 19%. The trends of PM 2.5 and NO 2 were significantly correlated with mobility data. The NO 2 and SO 2 tropospheric concentrations and the total aerosol optical depth at 550 nm obtained from satellite data during the lockdown in 2020 were also lower than during the same period in 2019. Our results can be used to evaluate possible mitigation strategies for outdoor air quality in a longer term beyond this lockdown.

The concentration of major air pollutants during the movement control order due to the COVID-19 pandemic in the Klang Valley, Malaysia

“…The lower numbers of motor vehicles and a limited number of industrial, construction and combustion activities would be expected to reduce the concentrations of PM 10 and PM 2.5 in ambient air. These results support similar previous studies on the levels of NO 2 , CO, PM 10 and PM 2.5 in ambient air recorded during the lockdown in Malaysia from neighbouring countries including Singapore ( Li & Tartarini, 2020 ) and Thailand ( Stratoulias & Nuthammachot, 2020 ) and other parts of the world as suggested by Mahato et al (2020) , Menut et al (2020) and Tobías et al (2020) .…”

Spatiotemporal Variations and Contributing Factors of Air Pollutant Concentrations in Malaysia during Movement Control Order due to Pandemic COVID-19

“…The Malaysian government implemented comprehensive and strict measures to stop the spread of COVID-19 nationwide (Table S1). These control measures restricted the movement of people hence reduced numbers of vehicles on the roads which in turn may improve air quality across the country (Dutheil et al, 2020;Li and Tartarini, 2020). This is consistent with a report from Google which exhibits that mobility levels in Malaysia decline immediately after the enforcement of MCO except for residential category (Fig.…”

“…Further investigation using pairwise comparison based on student t-test with Bonferroni correction were exhibits the daily average of WS, T, and RH during MCO were not significantly different when compared with daily average recorded before MCO. This suggests that pollution decline during MCO might not contributed by the changes in meteorology alone but can likely be attributed to changes in daily and economic activities due to COVID-19 containment measures (Li and Tartarini, 2020;Navinya et al, 2020). Table 3 shows the ambient air quality standard from the World Health Organization (WHO) and the Department of Environment (DOE) Malaysia.…”

Air Quality, Atmospheric Variables and Spread of COVID-19 in Delhi (India): An Analysis

“…With the upswing of the pandemic, the government imposed several restrictions on vehicle movements in worst effected Chinese cities to control air pollution, and the private vehicle restriction policy could bring down PM2.5 pollution by 32% (Chen et al, 2020). Li and Tartarini (2020) highlighted that NO2 and SO2 had the highest reduction in concentration during the lockdown period in Singapore and linked their associations with restricted mobility trends.…”