epa10980295 Indian students and activist wear face masks as they hold placards during the 'Kolkata Clean Air' awareness campaign in Kolkata, eastern India, 17 November 2023. Students of Kolkata participate in a campaign for more trams to be introduced into the transportation system to lower air pollution levels. According to the World Health Organization (WHO), Kolkata has the worst air quality of any major city in the world. EPA/PIYAL ADHIKARY
