The Central Pollution Control Board released the city-wise air quality index (AQI) on Friday, with Bihar's Motihari and Siwan having the highest AQI at 413 and 406, respectively. This is followed by Bettiah (395), Darbhanga (388), Begusarai (381), Buxar (377), Jind (371), Purnia (358), Saharsa (358), Gurugram (353) and Delhi (346).