Bangladesh measured to be the country with the worst air quality in the world in 2021, while India is home to 63 of the 100 most polluted cities in new World Air Quality Report. 

Hundreds of millions of people around the world are breathing in polluted air that far exceeds World Health Organization (WHO) guidelines, with the Indian city of New Delhi topping the list as the most polluted capital in the world for the fourth consecutive year.

According to a new World Air Quality Report put together by Swiss organisation IQAir that analysed real-time air quality data from tens of thousands of monitoring stations across the globe, it ranked Bangladesh as the world’s most polluted country, with PM2.5 concentrations  –  particulate matter that are 2.5 micrometres and smaller in length – reaching up to 76.9 micrograms per cubic metre. Scientists have linked persistent exposure to PM2.5 to many long term health issues including heart and lung disease, as well as 7 million premature deaths each year. 

Chad, Pakistan, Tajikistan, and India, respectively take the other top four countries with the worst air quality in the world. Overall, Central and South Asia had some of the worst air quality and was home to 46 of the world’s 50 most polluted cities. 

Aside from its capital New Delhi, India is also home to another 62 of the 100 most polluted places listed in the report, where more than half are situated in the north of the country, including Haryana and Uttar Pradesh. The annual average PM2.5 levels in India was about 58.1 µg/m³ in 2021, “ending a three-year trend of improving air quality” and a clear sign that the country has returned to pre-pandemic levels. 

The report says that major sources of air pollution in India derived from vehicular emissions, power generation, industrial waste, smoke from cooking, the construction sector, and crop burning. In November 2021, air pollution reached to such severe levels, that they were forced to shut down several large power plants around Delhi.

Elsewhere, air quality in China has been found to be improving where more than half its cities saw lower levels of air pollution in 2021 compared to the previous year. The positive trend could be attributed to strict emission control and reduction of coal power plant activity near populated cities. 

The South Pacific island nation of New Caledonia carries the mantle for the cleanest air quality, while Finland boasts the lowest PM2.5 concentrations among developed countries. 

However, the report made a grim note that out of the 6,475 cities in 117 countries, regions and territories that they measured, only 3% of cities and no country met the latest and stricter WHO PM2.5 annual air quality guidelines that were updated in September 2021. Under the new rules, acceptable annual exposure to PM2.5 has been halved to 5 µg/m³ following research showing fine particulate matter to be more harmful to humans than previously thought.

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Featured image by: Mark Danielson (CC BY-NC 2.0)