The Impact of the Control Measures during the COVID-19 Outbreak on Air Pollution in China

Abstract

The outbreak of the COVID-19 virus in Wuhan, China, in January 2020 just before the Spring Festival and subsequent country-wide measures to contain the virus, effectively resulted in the lock-down of the country. Most industries and businesses were closed, traffic was largely reduced, and people were restrained to their homes. This resulted in the reduction of emissions of trace gases and aerosols, the concentrations of which were strongly reduced in many cities around the country. Satellite imagery from the TROPOspheric Monitoring Instrument (TROPOMI) showed an enormous reduction of tropospheric NO2 concentrations, but aerosol optical depth (AOD), as a measure of the amount of aerosols, was less affected, likely due to the different formation mechanisms and the influence of meteorological factors. In this study, satellite data and ground-based observations were used together to estimate the separate effects of the Spring Festival and the COVID-19 containment measures on atmospheric composition in the winter of 2020. To achieve this, data were analyzed for a period from 30 days before to 60 days after the Spring Festivals in 2017–2020. This extended period of time, including similar periods in previous years, were selected to account for both the decreasing concentrations in response to air pollution control measures, and meteorological effects on concentrations of trace gases and aerosols. Satellite data from TROPOMI provided the spatial distributions over mainland China of the tropospheric vertical column density (VCD) of NO2, and VCD of SO2 and CO. The MODerate resolution Imaging Spectroradiometer (MODIS) provided the aerosol optical depth (AOD). The comparison of the satellite data for different periods showed a large reduction of, e.g., NO2 tropospheric VCDs due to the Spring Festival of up to 80% in some regions, and an additional reduction due to the COVID-19 containment measures of up to 70% in highly populated areas with intensive anthropogenic activities. In other areas, both effects are very small. Ground-based in situ observations from 26 provincial capitals provided concentrations of NO2, SO2, CO, O3, PM2.5, and PM10. The analysis of these data was focused on the situation in Wuhan, based on daily averaged concentrations. The NO2 concentrations started to decrease a few days before the Spring Festival and increased after about two weeks, except in 2020 when they continued to be low. SO2 concentrations behaved in a similar way, whereas CO, PM2.5, and PM10 also decreased during the Spring Festival but did not trace NO2 concentrations as SO2 did. As could be expected from atmospheric chemistry considerations, O3 concentrations increased. The analysis of the effects of the Spring Festival and the COVID-19 containment measures was complicated due to meteorological influences. Uncertainties contributing to the estimates of the different effects on the trace gas concentrations are discussed. The situation in Wuhan is compared with that in 26 provincial capitals based on 30-day averages for four years, showing different effects across China.

Assessing the immediate impact of COVID-19 lockdown on the air quality of Kolkata and Howrah, West Bengal, India

“…Lockdown of the production sectors, restriction on human mobility, and controlled public transportation system have resulted in the lowering of emission of pollutants. Studies by various scholars have shown how the lockdown has improved the ambient air quality, like in India (Gautam 2020 ; Mahato et al 2020 ; Sikarwar and Rani 2020 ; Srivastava et al 2020 ), the USA (Berman and Ebisu 2020 ), Mexico (Méndez-Arriaga 2020 ), Kazakhstan (Kerimray et al 2020 ), Iran (Abdul Halim et al 2018 ), China (Fan et al 2020 ; Zambrano-monserrate et al 2020 ) especially in Wuhan (Cole et al 2020 ; Lu et al 2020 ; Sicard et al 2020 ; Song et al 2016 ; Wang and Su 2020 ), Barcelona in Spain (Tobías et al 2020 ), Sao-Paulo in Brazil (Nakada and Urban 2020 ), Milan in Italy (Collivignarelli et al 2020 ), and Salé City in Morocco (Otmani et al 2020 ).…”

Impacts of COVID-19 on a Transitioning Energy System, Society, and International Cooperation

“…While COVID-19 restrictions have reduced carbon emissions, alongside other GHGs, pollutants, and aerosols, the easing of these restrictions is likely to see an uptick in emission levels. This has already been noted in parts of China, the earliest affected region of the pandemic [11,12]. One suggested approach emerging from the pandemic is the concept of 'glocalization'.…”

“…This analysis also showed that concentrations of NO 2 , SO 2 , and PM remained low, while CO levels increased soon after the initial decline due to COVID-19. As a result, air quality was improved overall, but, likely due to a reduction in NO 2 in the air; O 3 levels were increased for all 26 provincial capitals [11]. Focusing on nitrogen oxides (NO x ), it was confirmed that levels decreased considerably (~50%) for most provinces compared to pre-COVID-19 lockdowns, and only moderately rebounded (~26%) after back-to-work orders were issued for most eastern Chinese provinces.…”

The Impact of Ambient Air Pollution Toward Coronavirus Disease 2019 (Covid19): A Literature Review

“…However, the concentration of CO in the air is less affected and tends to increase as in previous years (64). The decrease in air pollution occurred during the Covid19 pandemic, but besides that it can increase the build-up of waste in the form of medical waste (masks, gloves, and hand sanitizers) in the environment (65).…”