Three GIIS researchers Dr. Asheshwor Man Shrestha, Dr. Uttam Babu Shrestha and Dr. Suraj Bhattarai along with their collaborators from the RMIT University, Australia (Roshan Sharma), The University of Adelaide (Hanh Ngoc Thi Tran), Australia and Institute for Advanced Sustainability Studies, Germany (Dr. Maheswar Rupakheti) examined the impacts of COVID-19 lockdowns on Air quality of 40 cities worldwide. As a response to prevent coronavirus, government countries worldwide are taking measures like lockdown and there are several media reported that lockdown induced air pollution reduction. However, a global-scale analysis of the change in air pollution level was not yet conducted. GIIS researchers measure the changes in concentrations of six air pollutants: PM2.5, PM10, O3, SO2, CO, and NO2 in 40 cities between February, March 2019, and 2020.