Demystifying a Possible Relationship between COVID-19, Air Quality and Meteorological Factors: Evidence from Kuala Lumpur, Malaysia

In the present study, pollutants levels from 24 th March-31 st May in 2020 were compared with the same time period in 2019 to estimate the impact of lockdown on air pollutants levels in 39 different cities of India (including 10 Indian cities considered among the world's 20 most polluted cities). Data for air pollutants was obtained from the Central Pollution Control Board (CPCB) which was statistically analyzed. Tropospheric NO2 column retrieved from Ozone Monitoring Instrument (OMI) were compared between 2019 and 2020 to compare the NO2 levels. Impact of lockdown measures on Ghaziabad which is the world's most polluted city and Patiala which showed maximum reduction during the lockdown period in the present study was studied in detail. After the implementation of lockdown measures, air pollution decreased but with substantial variation among pollutants. The most significant reduction was observed for nitrogen dioxide (NO2) (3-79%) and carbon monoxide (CO) (2-61%), pollutants which are mainly related to traffic emissions. Ozone (O3) showed a mixed trend with increasing levels at some cities which may be attributed to lower titration of O3 by NO. Maximum reduction observed in PM10 and PM2.5 was 58 and 57%, respectively during the lockdown period in 2020 as compared to the previous year. Air quality of the cities also improved in 2020. During the lockdown period in 2020, AQI of only 15% of cities was in the 'Unhealthy' category (151-200) while in 2019, 56% of cities were in the 'Unhealthy' category. In Ghaziabad and Patiala all the pollutants showed significant reduction after lockdown implementation except O3. Diurnal patterns of PM10, PM2.5, CO and NO2 showed lower values during lockdown period in 2020 with less distinct bimodal patterns as compared to 2019. The present study provides evidence that widespread implementation of air pollution measures can result in immediate air quality benefits.

Section: Accepted Manuscriptsupporting

confidence: 90%

Section: Accepted Manuscriptmentioning

confidence: 93%

COVID-19 and Air Pollution in Indian Cities: World’s Most Polluted Cities

Kumari¹,

Lakhani²,

Kumari³

2020

“…The neighboring nation of Malaysia reported a national-wide drop of PM 2.5 between 11.3 and 23.7% during 18 March to 14 April 2020 compared to 14 to 17 March 2020 (Abdullah et al, 2020). Suhaimi et al (2020) showed a reduction of PM 2.5 , NO 2 , CO, and SO 2 by 3 to 36%, 43 to 68%, 1 to 48%, and 2 to 48% according to different regions between 18 March and 21 April 2020 in Malaysia (Suhaimi et al, 2020). Nadzir et al (2020) reported that CO concentrations decreases ranging from 40.5 to 47.5%, but PM 2.5 levels showed a both increase and decrease according to different regions in Malaysia during the period from 18 March to 08 April 2020 (Nadzir et al, 2020).…”

Section: Changes In Air Quality In Southeast Asiamentioning

confidence: 99%

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

Tartarini

2020

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.

“…High concentrations of NO 2 , CO, and SO 2 were also observed in the late evening is generally due to meteorological influence and atmospheric stability (Awang et al, 2000). Nonetheless, highest concentrations of PM 2.5 , NO 2 , and CO were found in urban stations which it is highly possible that these concentrations are from vehicular emissions (Mohd Nadzir et al, 2020;Suhaimi et al, 2020). Although there was change in daily activities during MCO, similar diurnal patterns were observed; however, significant lower readings were observed in all settings.…”

Section: Temporal and Spatial Variations Of Air Pollutantsmentioning

confidence: 97%

“…However, the study also reported an increase in PM 10 and PM 2.5 concentrations in one of their monitoring stations due to the transport emissions from other regions, local burning activities, and the highway construction nearby. A study by Suhaimi et al (2020) showed that PM 10 , SO 2 , NO 2 , and CO concentrations were reduced between 5 and 50% on the first week of MCO in urban setting. Also, a study by Kanniah et al (2020) revealed that the highest reductions were observed in NO 2 concentrations in Malaysian urban region.…”

Section: Introductionmentioning

confidence: 99%

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

Ash’aari

Aris

Ezani

et al. 2020

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 suburban , urban, and industrial settings with relatively small contributions from meteorological conditions. Overall, compared to before MCO, average concentrations of PM 2.5 , CO, and NO 2 reduced by 23.1%, 21.74%, and 54.0%, respectively, while that of SO 2 was constant. The highest reduction of PM 2.5 , CO, and NO 2 were observed in stations located in urban setting, where 63% stations showed significant reduction (p < 0.05) for PM 2.5 and CO, while all stations showed significant reduction in NO 2 concentrations. It was also revealed that 70.5% stations recorded lower concentrations of PM 2.5 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 PM 2.5 , while the highest of NO 2 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.