GENEVA, Switzerland: An annual global survey by Swiss air purifier maker IQAir reported that Lahore, Pakistan, was the city with the worst air in the world in 2022, rising more than 10 places.

Also, Chad in central Africa overtook Bangladesh as the country with the most polluted air in 2022, according to the report.

IQAir, whose annual survey is widely cited by researchers and government organizations, measures air quality levels based on the concentration of PM2.5., which are lung-damaging airborne particles.

In 2021, Lahore's air quality worsened to 97.4 micrograms of PM2.5 particles per cubic meter from 86.5, making it the most polluted city in the world, followed by Hotan, the only Chinese city in the top 20, with PM2.5 levels of 94.3, which was an improvement from 101.5 in 2021.

The World Health Organization recommends a maximum PM2.5 concentration of 5 micrograms per cubic meter.

Chad led the list of countries, with an average level of 89.7, followed by Iraq with 80.1.

Pakistan, which had two of the five cities with the worst air in 2022, stood third in the country-wide ranking at 70.9, followed by Bahrain at 66.6.

The report further said that one in 10 people in the world were living in an area where air pollution was a threat to health.

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

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