Conclusion
The present study demonstrates the impact of COVID-19 pandemic confinement on air quality among the populous site of four major metropolitan cities in India i.e., site 1—ITO, Delhi, site 2—Worli, Mumbai, site 3—Jadavpur, Kolkata, and site 4—Manali Village, Chennai. A data set was constructed for AQI, PM2.5, PM10, NO2, NH3, SO2, CO, and ozone from January 1, 2020 to May 31, 2020 from the Central Pollution Control Board (CPCB). Pearson’s correlation analysis and Welch’s t test were performed for the determination of statistically significant improvement in the air quality during the confinement period. A remarkable drop falls of 44%, 59%, 59%, and 6% in AQI which was observed during COVID-19 pandemic confinement in sites 1, 2, 3, and 4 respectively. It can be concluded that remarkable improvement in the air quality during confinement period was observed as the p values of the test for all of the four sites were very less than the significance level (α = 0.05). Besides, the Welch’s t test was supported by findings of Pearson’s correlation analysis in which the prominent pollutants (PM2.5 and PM10) were also found to be highly correlated with AQI. Although a significant impact on planetary health can be noticed during COVID-19 pandemic confinement, the circumstance is momentary and limits for a short duration i.e., only up to confinement period.