Lahore is the most polluted city in the world, according to Swiss air quality monitoring platform IQAir. In November, the air was so poisonous that authorities issued a citywide lockdown, closing schools, markets, and parks for four days, and advising people to stay indoors.
Other cities in South Asia have similarly alarming levels of air quality: Eight out of the top 10 most polluted cities globally are in the region. Causes include rapid urbanization, construction, vehicular pollution, coal-fueled power plants, crop burning, and the operation of brick kilns. Air quality in the region is at its worst from October to February due to atmospheric conditions which cause pollutants to be trapped closer to the ground.
Source: Gig workers in South Asia are suffering health impacts from pollution – Rest of World