According to Central Pollution Control Board, Bihar's Siwan has the worst level of air pollution on Saturday with an air quality index of 435. This is followed by Bihar's Katihar (422), Haryana's Faridabad (416) and Delhi (402). Other cities include Haryana's Charkhi Dadri (392), Rajasthan's Bhiwadi (386), Bihar's Motihari (383), UP's Noida (381), Haryana's Hisar (381) and UP's Meerut (380).