As per the Central Pollution Control Board, Mizoram's Aizawl with an air quality index (AQI) of 29 had the cleanest air on Thursday. This is followed by Gangtok (30), Tirunelveli (31), Ariyalur (34) and Thanjavur (34). Meanwhile, Delhi was the most polluted city with an AQI of 377, followed by Mandideep (329), Hapur (320), Ghaziabad (316) and Gurugram (302).