These were the best and worst places for air quality in 2021, new report shows

The report by IQAir, a Swiss air quality technology company, analyzed air quality data from 6,475 cities in 117 countries. It found that the cities with the worst air quality were largely located in Asia, with India, Pakistan, and Bangladesh accounting for 49 of the 50 most polluted cities globally. The report highlighted that Delhi, the capital of India, was the world's most polluted capital city, with an average annual PM2.5 concentration of 85.1 μg/m³, which is nearly 17 times the World Health Organization's (WHO) recommended limit. On the other hand, the cities with the cleanest air were predominantly in Europe, with Zürich, Switzerland, being the city with the best air quality globally. The report also noted that the COVID-19 pandemic had a temporary positive impact on air quality in some regions due to reduced economic and transportation activities. The findings emphasize the ongoing challenge of addressing air pollution, which remains a significant threat to public health worldwide.