Spatiotemporal Analysis of Nitrogen Dioxide (NO2) Dynamics in Lucknow, India: A Comparative Study of Pre-Lockdown and COVID-19 Lockdown Periods using Google Earth Engine

This research leverages the cloud-computing capabilities of Google Earth Engine (GEE) to perform a high-resolution spatiotemporal analysis of nitrogen dioxide (NO2) dynamics in Lucknow, Uttar Pradesh. Using the Sentinel-5P TROPOMI sensor, the study quantifies the shift in tropospheric NO2 concentrations by comparing the COVID-19 lockdown period of April 2020 against an April 2019 baseline. To go beyond raw atmospheric data and assess human health implications, we implemented a population-weighted exposure model utilizing the Gridded Population of the World (GPWv4) dataset.The findings indicate a substantial reduction in NO2 concentrations during the lockdown, primarily driven by the cessation of anthropogenic activities in the transport and industrial sectors. By prioritizing air quality data in high-density urban zones, the results reveal a significant localized clearing of the atmosphere that maximized the "avoided health burden" for the city's residents. This study demonstrates that cloud-based remote sensing is an indispensable tool for urban environmental management, providing a definitive scientific baseline for future sustainable air quality policy in the Indo-Gangetic Plain..