The cities with the world’s cleanest and filthiest air, ranked

Escape route.
Escape route.
Image: REUTERS/Danish Siddiqui
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The day after Diwali brings with it a lull after weeks-long festive rush. And it brings bad air.

Indians, already reeling under bad air days, watch the air quality index with the anticipation of a nail-biting thriller. Will it teeter between “very poor” and “severe,” or will it cross over to the dark red “hazardous” zone? Will the room air purifier ever stop wheezing? Will the breeze finally take away all the smoke from crop burning, and vehicular and industrial pollution?

While the colours of the air quality index take over the lives of residents of Delhi and much of north India, there’s another thought that reemerges every year. Are there other cities with air as toxic as Indian cities, which, according to reports, causes millions of deaths every year?

According to IQAir, a Swiss air technology company that pulls together air quality indices from across the world, Delhi currently (Nov. 15) has the most polluted air in the world. And, there are three Indian cities in the list of the 20 most polluted cities in the world.

This ranking is based on real-time data, which means that Delhi would have been at the top of that list on Nov. 10, when the AQI was at a record high.

Based on a 2019 average, 14 of the 20 cities with the world’s worst air were in India. The World Health Organization considers fine particulate matter pollution—known as PM2.5 pollution—to be safe at a level below 25 μg/m3 per day. In most parts of Delhi, the PM2.5 level has been roughly 10 times this threshold.

In view of these emergency conditions, Indian courts have also banned the use of firecrackers till Nov. 30, during which time the Hindu festival of Diwali also falls. Hindus consider lighting firecrackers as part of traditional Diwali celebrations.

Despite the ban, some Indians burnt firecrackers yesterday (Nov. 14), adding to the AQI woes. Keeping in mind this annual event—meteorological conditions that lead to an “air lock” in India’s north, and leads to PM2.5 and PM10 being trapped—Indians have often expressed the desire to migrate to other parts of India, or even the world.

For air-quality aspirants, these are currently the top 10 cities in the world with the best air.