Assessing the immediate effect of COVID-19 lockdown on air quality: A case study of Delhi, India

Abstract

In India, the nationwide lockdown due to COVID-19 has been implemented on 25 March 2020. The lockdown restrictions on more than 1.3 billion people have brought exceptional changes in the air quality all over the country. This study aims to analyze the levels of three major pollutants (PM2.5, PM10, and NO2) before and during the lockdown in Delhi, one of the world’s most polluted cities. The data for PM2.5, PM10, and NO2 concentrations are derived from 38 ground stations dispersed within the city. The spatial interpolation maps of pollutants for two times are generated using Inverse Distance Weighting (IDW) model. The results indicate the lowering of PM2.5, PM10, and NO2 concentrations in the city by 93%, 83%, and 70% from 25 February 2020 to 21 April 2020 respectively. It is found that before one month of the lockdown the levels of air pollution in Delhi were critically high and far beyond the guideline values set by the World Health Organization. The levels of air pollution are historically low after the lockdown. Considering the critically degraded air quality for decades and higher morbidity and mortality rate due to unhealthy air in Delhi, the improvement in air quality due to lockdown may result as a boon for the better health of the city’s population.

A picture of Delhi’s regional air quality during diminished anthropogenic activities in the COVID-19 era

“…Many countries face globally tremendous issues to mitigate the global pandemic COVID-19, and still, many countries are facing the same (Sikarwar and Rani 2020;Li et al 2020). The new infectious (COVID-19) disease was first identified in Wuhan City of China in December 2019 (Gautam et al 2021b;He et al 2020;Srivastava et al 2020).…”

“…Despite several issues reported due to pandemic such as economy and human health, it was vice versa for pollution related issues. In 2020 several research studies showed a reduction in pollution levels in Delhi, which reflected improved air quality (Karuppasamy et al 2020;Agarwal et al 2020;Sikarwar and Rani 2020;Mahato et al 2020;Hamaa et al 2020;Srivastava et al 2020;Kumar et al 2020). All types of transportation services, including rail, road, air, and all industrial units except essential services, were suspended in 2020, leading to a dramatic reduction in air pollution (Kumari and Tosniwal 2020), but in 2021 there were exceptions given for movement.…”

“…As per the World Air Quality (IQAir) (WORLD AIR QUALITY REPORT 2019) report, six major Indian cities with poor air quality were recorded globally. Delhi has consistently been ranked as one of the most polluted cities in developing countries (Sikarwar and Rani 2020). The sources of air pollution in Delhi include power generation, industry, traffic, household activities, pavement dust, and biomass burning (Bherwani et al 2020;Venter et al 2020).…”

“…The sources of air pollution in Delhi include power generation, industry, traffic, household activities, pavement dust, and biomass burning (Bherwani et al 2020;Venter et al 2020). Due to poor air quality, a community health emergency was declared in 2017 for Delhi by the Indian Council of Medical Research (ICMR) (Sikarwar and Rani 2020). To tackle this situation, several short-term and long-term measures were taken to improve the air quality.…”

Assessing the Immediate Impact of COVID-19 Lockdown on the Air Quality of Kolkata and Howrah, West Bengal, India

“…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), U.S. (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; Q. 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) In India, air pollution has become a topic of intense debate at all levels mainly because of the enhanced anthropogenic activities e.g. rapid urbanization, higher population growth, increased energy consumption, and vehicular emission and industrial emission (Dadhich et al 2018;Ghose et al 2005;Gupta et al 2008).…”