About 90% of the world’s population will live with unhealthy air quality by 2022, and only six countries met the World Health Organization’s recommendations for safe levels of air pollution, according to a new report from Swiss technology company IQAir.

IQAir measured air quality based on the concentration of lung-damaging airborne particles known as PM2.5. Research shows that exposure to such particulate matter can lead to heart attacks, asthma attacks and premature death. Studies have also linked long-term exposure to PM2.5 to higher mortality rates from Covid-19.

When the WHO first published air quality guidelines in 2005, it said acceptable levels of air pollution were less than 10 micrograms per cubic meter. In 2021, WHO changed its benchmark guidelines to less than 5 micrograms per cubic meter.

The report found that the top five most polluted countries in 2022 were Chad, Iraq, Pakistan, Bahrain and Bangladesh. The most polluted cities in the world were Lahore, Pakistan; Hotan, China; Bhiwadi, India; Delhi, India; and Peshawar, Pakistan.

Lahore’s air quality deteriorated to 97.4 micrograms of PM 2.5 particles per cubic meter in 2022 from 86.5 in the previous year, making it the most polluted city in the world.

The report also said that India and Pakistan have the worst air quality in the Central and South Asian region, where more than half of the population lives in areas where the concentration of PM 2.5 particles is about seven times higher than the levels proposed by WHO.

In the US, the most polluted major cities were Columbus, Ohio, followed by Atlanta, Chicago, Indianapolis and Dallas. Air quality in Columbus reached 13.1 micrograms of PM 2.5 particles per cubic meter in 2020, making it the most polluted major city in the US

The Biden administration this year proposed limiting industrial particulate pollution from the current annual level of 12 micrograms per cubic meter to a level between 9 and 10 micrograms per cubic meter. Some public health advocates criticized that proposal for not going far enough.

Only six countries met WHO’s updated health limits: Australia, Estonia, Finland, Grenada, Iceland and New Zealand, the report said. The 2022 report used air quality data from more than 30,000 air quality regulatory monitoring stations and air quality sensors from 7,323 cities in 131 countries, regions and territories.

According to the Energy Policy Institute at the University of Chicago, air pollution reduces average life expectancy worldwide by more than two years. Sixty percent of air pollution by particulate matter comes from the combustion of fossil fuels.

“Too many people around the world don’t know they breathe polluted air,” Aidan Farrow, senior air quality scientist at Greenpeace International, said in a statement.

“Air pollution monitors provide hard data that can inspire communities to demand change and hold polluters accountable, but when monitoring is patchy or uneven, vulnerable communities can run out of data,” Farrow said.