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Relative changes (%) of PM2.5 concentrations before, during, and post lockdown periods (depending on each city lockdown date). Reduction and increase in PM2.5 (μg/m3) levels in 2020 as compared to 2-years average values. Maximum decline in PM2.5 concentrations was showed in Islamabad, Abu-Dhabi, Kathmandu, and Lima, while the lower decrease was obtained for Dhaka, Manama, Kampala, Bogota, and Algiers. White space stands for lack of dataset for the city.
