Air quality during 2010-2020 over two mega cities in the west zone of India- with special reference to COVID-19 lockdown.

Abstract

Abstract With the advent of industrialization in the world's major metropolitan areas, air pollution has steadily increased. Several strict laws are imposed by the authorities to minimize the impact of pollution in urban dwellings. The lockdown restrictions during COVID-19 pandemic resulted in major air quality improvements worldwide. However, episodic improvements in air quality understates explicit picture of air quality. This merits the cause for spatio-temporal analysis of air quality over two most affected metropolitan regions in west India: Pune and Mumbai, in the past decade. We investigated the air quality by collecting hourly primary data of PM10, SPM, SO2, and NOx at three locations in Pune while daily data of PM10, SO2, and NOx was obtained at eleven locations in Mumbai. As the data were copiously available (2010–2020), decadal, inter-intra seasonal analysis was carried out at multi-timescales. This contributed in intensively exploring the variations in 2020 resulting in critical evaluation during the pandemic year. Against the overall deterioration in air quality in the past decade, finer refinement in air quality was witnessed over Pune during the lockdown. At Mumbai, an overall reduction of 59% was observed at all the locations. In both the cities, the pollution behaviour varied on a spatio-temporal scale within the cities. The study, therefore, infers the distinctiveness of pollutant behaviour on a spatial scale within the city rather than overall average for the city. It also recommends strengthening the air monitoring network in urban dwellings to track varied sources and formulate precise urban planning.