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. 2021;37(1):79-103.
doi: 10.1007/s10453-020-09673-5. Epub 2020 Nov 17.

COVID-19 lockdown: a boon in boosting the air quality of major Indian Metropolitan Cities

Devendra Singh Rathore  1 , Chirmaie Nagda  2 , Bhavya Singh Shaktawat  1 , Tanushree Kain  1 , Chandrapal Singh Chouhan  3 , Rakeshwar Purohit  4 , Harish  5 , Rama Kanwar Khangarot  6 , Girima Nagda  2 , Lalit Singh Jhala  7
Affiliations

COVID-19 lockdown: a boon in boosting the air quality of major Indian Metropolitan Cities

Devendra Singh Rathore et al. Aerobiologia (Bologna). 2021.

Abstract

Abstract: The COVID-19 lockdown has not only helped in combating the community transmission of SARS-CoV-2 but also improved air quality in a very emphatic manner in most of the countries. In India, the first phase of COVID-19 lockdown came into force on March 25, 2020, which was later continued in the next phases. The purpose of this study was to investigate the result of lockdown on air quality of major metropolitan cities-Delhi, Mumbai, Kolkata, Chennai, Bengaluru, Hyderabad, Jaipur, and Lucknow-from March 25 to May 3, 2020. For this study, the concentration of six criteria air pollutants (PM2.5, PM10, CO, NO2, SO2, and O3) and air quality index during the COVID-19 lockdown period was compared with the same period of the previous year 2019. The results indicate a substantial improvement in air quality with a drastic decrease in the concentration of PM2.5, PM10, CO, and NO2, while there is a moderate reduction in SO2 and O3 concentration. During the lockdown period, the maximum reduction in the concentration of PM2.5, PM10, CO, NO2, SO2, and O3 was observed to be - 49% (Lucknow), - 57% (Delhi), - 75% (Mumbai), - 68% (Kolkata), - 48% (Mumbai), and - 29% (Hyderabad), respectively. The value of the air quality index (AQI) also dwindled significantly during the COVID-19 lockdown period. The maximum decline in AQI was observed - 52% in Bengaluru and Lucknow. The order of AQI was satisfactory > moderate > good > poor and the frequency order of prominent pollutants was O3 > PM10 > PM2.5 > CO > NO2 > SO2 during the lockdown period in all the aforementioned metropolitan cities.

Keywords: Air quality index; COVID-19; Criteria pollutants; Lockdown; Metropolitan cities; Prominent pollutant.

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Conflict of interest statement

Conflict of interestThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Locations map of eight metropolitan cities of India. Source: https://www.google.com/maps/@24.1580341,82.7349726,5z
Fig. 2
Fig. 2
Daily variation and average difference in mean PM2.5, PM10 and CO concentrations during March 25 to May 3, 2020 (COVID-19 lockdown period), and March 25 to May 3, 2019
Fig. 3
Fig. 3
Daily variation and average difference in mean NO2, SO2, and O3 concentrations during March 25 to May 3, 2020 (COVID-19 lockdown period), and March 25 to May 3, 2019
Fig. 4
Fig. 4
Daily variation and average difference in mean temperature and relative humidity during March 25 to May 3, 2020 (COVID-19 lockdown period), and March 25 to May 3, 2019
Fig. 5
Fig. 5
Daily variation in percentage and average difference in air quality index during March 25 to May 3, 2020 (COVID-19 lockdown period) and March 25 to May 3, 2019
Fig. 6
Fig. 6
Categorywise variation in air quality index during March 25 to May 3, 2020 (COVID-19 lockdown period), and March 25 to May 3, 2019
Fig. 7
Fig. 7
Frequency of prominent pollutant during March 25 to May 3, 2020 (COVID-19 lockdown period) and March 25 to May 3, 2019
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