Abstract
The worldwide spread of COVID-19 caused a nationwide lockdown in India from 24 March 2020 and was further extended up to 3 May 2020 to break off the transmission of novel Coronavirus. The study is designed to assess the changes in air quality from the pre-lockdown period to the during lockdown period in Kolkata and Howrah municipal corporation, West Bengal, India. GIS-based techniques include the spatial and temporal distribution of pollutants using interpolation method, and on the other hand, statistical methods like analysis of variance (ANOVA) was applied to determine the mean differences two phases and correlation matrix helps to understand the changing association of the pollutants in pre- and during lockdown phases. Significant correlations have been found among the pollutants, ANOVA (Two-Way) has shown the significant mean difference of NAQI between the two phases, F(1,611) = 465.723, p < 0.0001; pairwise comparison for Ballygunge has shown the highest mean difference 108.194 at p < 0.0001 significant level between lockdown and pre-lockdown phase. Significant positive correlation has been found between PM2.5, PM10 (0.99*); PM2.5, NO2 (0.81*); PM10, NO2 (0.81*); CO, NO2 (0.77*) and some negative correlations have also been found between O3, NO (− 0.15); O3 and NH3 (− 0.36) in the pre-lockdown phase. The reduction amount of mean concentration from the pre-lockdown phase to during lockdown of the main pollutants like PM2.5, PM10 and NO2 are ~ 58.71%, ~ 57.92% and ~ 55.23%. Near Rabindra Bharati University constant emission of PM2.5, 10 and NO2 have been recorded due to the nearby Cossipore thermal power station.
Highlights
In December 2019, a disease, later named COVID-19, was identified in Wuhan of China and within 3 months more than 100 countries have been affected by devastating consequences (Wang and Su 2020)
The first confirmed case of COVID-19 in India was identified on 30 January 2020 in Kerala and hiked to three by 3 February when three students returned from Wuhan, China, and the first death was recorded on 12 March
This study aims to evaluate the changes in air quality in terms of pollutant concentration during the implementation of the lockdown measures considering the COVID-19 pandemic in Kolkata and Howrah, the ‘twin cities’ of West Bengal
Summary
In December 2019, a disease, later named COVID-19, was identified in Wuhan of China and within 3 months more than 100 countries have been affected by devastating consequences (Wang and Su 2020). The first confirmed case of COVID-19 in India was identified on 30 January 2020 in Kerala and hiked to three by 3 February when three students returned from Wuhan, China, and the first death was recorded on 12 March. Till 3 May 2020, the cumulative number of total infection by COVID-19 was more than forty thousand across India (GOI 2020). West Bengal the fourth-most densely inhabited state in the country recorded the first positive case of COVID-19 on 17 March 2020 after a UK-returned student was tested positive. Countries have strictly restricted the movement of people and transportation, reducing human interactions, enforcing strict quarantine, prohibiting large-scale private and public gatherings, encouraging social-distancing, and restricting private and public transportations and economic behaviour (Fernandes 2020; He et al 2020; Wang and Su 2020)
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