A  ‘World Air Quality’ report published by Swiss firm IQAir on Tuesday says that India is the world’s eighth most polluted country in 2022, dropping from its fifth spot from the previous year.

IQAir measures air quality levels based on the concentration of lung-damaging airborne particles known as PM2.5. Its annual survey is widely cited by researchers and government organisations worldwide.

The current index was prepared using data from more than 30,000 air quality monitors in more than 7,300 locations in 131 countries, territories and regions.

What does the study say?

Indian cities on the list with worst air quality included Darbhanga, Asopur, Patna, Ghaziabad, Dharuhera, Chapra, Muzaffarnagar, Greater Noida, Bahadurgarh and Faridabad.

Seven cities in India, Tarakeswar, Digboi, Aladu, Kattupalli, Polampalli, Kharsawan and Muthaiyapuram, were also among the 15 least polluted regional cities in South Asia.

The report said India and Pakistan experienced the worst air quality in the Central and South Asian region, where nearly 60 per cent of the population lives in areas where the concentration of PM2.5 particles is at least seven times higher than WHO’s recommended levels.

The report also stated that Chad in central Africa had replaced Bangladesh as the country with the most polluted air last year. While Chad had an average level of 89.7. Iraq, which had the second most polluted air for a country, averaged 80.1.

Hotan, the only Chinese city in the top 20, followed Lahore with PM2.5 levels of 94.3, an improvement from 101.5 in 2021.

Bangladesh’s air quality improved from 2021, when it was tagged as the country with the worst air. It is ranked fifth in the latest report, with PM2.5 levels coming down to 65.8 from 76.9, Reuters reported.

The US Pacific territory Guam had cleaner air than any country, with a PM2.5 concentration of 1.3, while Canberra had the cleanest air for a capital city, with 2.8.

The report also said that one in 10 people globally were living in an area where air pollution poses a threat to health.

What causes this problem?

Over 50 percent of pollution in India comes from industry, followed by 27 per cent from vehicles, 17 per cent from crop burning and 7 per cent by domestic cooking. Over 2 million Indians lose their lives to causes attributed to air pollution.

In the urban areas, most of this pollution comes from industry and vehicles, whereas in the rural areas, most comes from the burning of organic material.

The main cause here is the material that is used as a fuel for the domestic stoves, and also in the heaters needed to keep the houses warm in the colder months.

Usually made from a wet mixture of pieces of wood, dried leaves, hay and dried animal dung, this is then fashioned into discs and dried in the sunshine. When burned, it produces smoke and other pollutants five times higher than if coal were burnt.

It is thought that in excess of 100 million households use these stoves up to 3 times a day, 7 days a week, a major reason for air pollution, especially small particles that stay in the air for a long period of time.

During autumn and winter, huge amounts of stubble are burnt in the fields as a way of preparing the ground for the next crop. This method is much cheaper than the alternative option of ploughing the residue back into the land.

The air quality in the capital of Delhi always drops to the “severe” category during these winter months. It is reported that this alone is responsible for 32 per cent of Delhi’s PM2.5 particulate matter. At 292 micrograms per cubic metre, the figure is 5 times higher than the World Health Organisation’s recommended safe limit.

A variety of other factors too play a role in worsening the air quality in India, from automobiles in India running on adulterated fuel, a common practice in South Asia, to humongous amounts of dust produced from the demolitions and subsequent building of new properties. All these varied factors combine to steadily worsen the air quality in Indian cities, a phenomenon now pushing its way into rural areas as well.

What are associated health risks?

The levels of the pollutant PM 2.5 in India are usually well above the World Health Organisation’s recommended level of exposure, often over 5 times higher, and this leads to serious respiratory problems for those exposed to it.

Records show that in 2019 over 1.6 million deaths were attributed to poor air quality. The cause of death ranged from strokes, diabetes, lung cancer and myocardial infarctions, all directly or indirectly related to complications resulting from exposure to air pollution.