Spatio-temporal variation in fine particulate matter and effect on air quality during the COVID-19 in New Delhi, India.

Abstract Novel Coronavirus disease has affected almost all the countries; which leads to the pandemic, impacting adversely on environment. The impact on environment during pre-and during lockdowns needs an attention to correlate the pollutants from industrial emissions and other factors. Therefore, the current study demonstrates the changes in fine particulate matter PM2.5, PM10 and effect on air quality during lockdown. The highest reduction was observed in lockdown I (25 March - 14 April) as compared to others lockdowns (between 15 April and 31st May 2020) due to the complete shutdown of industrial, transport, and construction activities. A significant reduction in PM2.5 and PM10 from 114.27 μg/m3 and 194.48 μg/m3 for pre-lockdown period to 41.41 μg/m3 and 86.81 μg/m3 for lockdown I was observed. The levels of air quality index fall under satisfactory category for lockdown I whereas satisfactory to moderate category for other lockdowns. The present study revealed a strong correlation between PM2.5 and PM10 levels during the pre-lockdown period (0.71) and through lockdown IV (0.76), which indicate that change in the PM10 level influences the PM2.5 level greatly. The findings of the present study could be scaled up nationwide and might be useful in formulating air pollution reduction policies in the future.