Bangladesh, Pakistan and India had the worst air quality in the world in 2023, according to a list published Tuesday by the Swiss company IQAir.

High levels of air pollution are known to cause hundreds of thousands of premature deaths in South Asia and millions worldwide.

The annual average concentration of PM2.5 – particulate matter with a diameter of less than 2.5 micrometers and extremely harmful to health – in Bangladesh was 15 times over the levels considered safe by the World Health Organization, according to the report by IQAir.

An average of 79.9 micrograms per cubic meter (μg/m3) was recorded in Bangladesh last year, whereas the WHO recommends a maximum five μg/m3.

Pakistan, with 73.7 µg/m3 per year, and India, with 54.4 µg/m3 per year, came in at second and third, respectively, in the list.

All three countries are from South Asia, where emissions from brick factories, burning stubble or using solid fuels to cook and keep warm in winter contribute significantly towards pollution.

IQAir underlined that brick factories and vehicle emissions contribute the most towards air pollution in Bangladesh.

Around 95 percent of the population of the country lives within a kilometer of a brick factory, most of them illegal, the company said.

According to data from the Swiss organization, air quality in the most polluted cities in these countries has been declining in recent years despite the adoption of various measures by the local authorities.

Delhi in India was the most polluted capital city, followed by Dhaka in Bangladesh and Ouagadougou in Burkina Faso.

“In 2023 air pollution remained a global health catastrophe, IQAir’s global data set provides an important reminder of the resulting injustices and the need to implement the many solutions that exist to this problem,” said Greenpeace International’s Senior Air Quality Scientist Aidan Farrow, according to the statement.

High levels of air pollution can shorten the lifespan of people living in large cities in the most polluted regions by up to five years on average, according to several studies. WHO estimates that about two million people die prematurely in South Asia due to air pollution.