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Overall percentage change of Sentinel 5P satellite observed NO2 concentration associated with different CRP categories compared to the pre-CRP from January 1st, 2019, to July 31st, 2020. Across all studied cities, NO2 significantly increased by 2.3% across 1699 world cities when mild policies were implemented, had no significant changes under moderate policies, and significantly decreased by about 5% when stringent CRPs were implemented across 1768 world cities.
