Air pollution continues to present one of the world’s biggest health hazards to people everywhere, contri-buting to about 7 million premature deaths annually. 600,000 of these deaths are children.

       Compounding this staggering health crisis, air pollution is estimated to cost the global economy upwards of $2.9 trillion per year due to fossil fuel emissions alone, while also contrib-uting to a range of severe environmental probl-ems.

       Air quality is determined by the levels of air pollut-ants PM2.5, PM10, ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide. In 2020, India had 46 of the world’s 100 most polluted cities, followed by China (42), Pakistan (6), Bangladesh (4), Indonesia (1), and Thailand (1), according to air quality tracker IQAir.

       All these cities had a PM2.5 air-quality rating of over 50. Nine out of the top 10 most polluted cities are in India. Hotan, in China’s Xinjiang, had the worst average air quality in 2020, with 110.2.