Comparative study on air quality status in Golden Quadrilateral cities before and during the COVID-19 lock down period.

The COVID-19 pandemics have affected every aspect of the human race and the world economy. The disease has been contaminated in almost every part of India. A threat for poor standards induced premature mortality from cardiovascular disease and respiratory diseases. Amongst the huge-reaching implications of the continuing COVID-19 outbreak, a significant enhancement in air quality was detected all around the globe after lockdowns enforced in several cities in India. The lockdown influenced the environment’s pollution level and improved air quality quickly due to very few human activities. The present work scientifically analyses the air pollutants (PM2.5, PM10, NO2, and SO2) with meteorological parameters in the golden quadrilateral cities. The purpose of this paper is to review the analysis of air quality of golden quadrilateral cities (Delhi, Kolkata, Chennai, and Mumbai). Data of air quality parameters are collectively taken from different locations from different regions of Delhi, Kolkata, Chennai, and Mumbai before lockdown and during the lockdown and compared the data of both periods. Comparison pre-lockdown and 2019 with respect to lockdown and 2020 respectively show a huge reduction in amounts of pollutants. Our objective is to find the implication of different lockdown measures on air quality levels in Delhi, Kolkata, Chennai, and Mumbai particularly this investigation is focused on PM2.5, PM10, NO2, SO2 which is directly transmitted by human action and formed through a chemical reaction in the atmosphere as well as quantify the short-range and long-range health impact.