Los Angeles had the lowest air quality in the United States in 2024, according to the annual World Air Quality Report from IQAir.
The annual report looks at data from more than more than 40,000 air quality monitoring stations across 8,954 locations in 138 countries, territories and regions, according to IQAir, an air technology company based in Switzerland.
The rankings are based on the annual average of concentrated micrograms of an air pollutant per cubic meter of air. The World Health Organization recommends 5 micrograms of pollutant per cubic meter.
Which countries have the lowest air quality?
Worldwide, the countries with the worst air quality were Chad, Bangladesh, Pakistan, the Democratic Republic of Congo and India. Chad had 91.5 micrograms of pollutant per cubic meter, IQAir said — more than 18 times more than what the WHO recommends. Bangladesh had 78, Pakistan had 73.7, the Democratic Republic of the Congo had 58.2, and India had 50.6 micrograms per cubic meter.
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But Byrnihat, India was the most polluted metropolitan area in 2024, the IQAir report said. The city had an annual average concentration of 128.2 micrograms per cubic meter of air. India was home to six of the nine most polluted global cities, IQAir said.
One hundred and twenty-six countries, or 91.3% of the world, exceeded the WHO guideline, according to the report.
Conditions on the ground in various countries can affect the amount of pollutants per cubic meter, IQAir said. Wildfires in the Amazon caused levels in parts of Brazil to nearly quadruple in the fall. The entire continent of Africa only has one moniotring station for every 3.7 million people, IQAir said, which may lead to inaccurate data for the region.
What parts of the U.S. have the best and worst air quality?
Most cities in the United States had between 5.1 and 15 micrograms of pollution per cubic meter of air, according to IQAir. A number of cities, especially along the West Coast, New England and in the Southwest, had between 0 and 5 micrograms of pollution per cubic meter, meeting WHO guidelines.
The major city with the worst air pollution was Los Angeles, California. The smaller municipality of Ontario, California, had the most pollution of any city, the report said.
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Seattle, Washington was the cleanest major city in the U.S., according to IQAir.
What parts of the world have the best air quality?
Australia, the Bahamas, Barbados, Estonia, Grenada, Iceland and New Zealand met the WHO guideline for air quality. The cleanest metropolitan area in the world was Mayaguez, Puerto Rico, with an annual average concentration of 1.1 micrograms per cubic meter of air.
The cleanest region is Oceania, which includes Australia, New Zealand, Papua New Guinea and hundreds of smaller islands. Fifty-seven percent of cities in the region met the WHO guideline, the IQAir report found.
Seventeen percent of cities included in the report met the annual WHO guideline, IQAir said. That’s an increase from 2023, when just 9% of cities met the guideline.
“While this marks some progress, much more work has yet to be done to protect human health, especially that of children,” IQAir said in the report.
Why is air quality so important?
Air pollution is a “critical threat to both human health and environmental stability, IQAir CEO Frank Hammes said in a news release announcing the findings of the report.
Ninety-nine percent of the world’s population lives in areas that do not meet recommended air quality guideline levels, according to WHO. Air pollution is the second leading global risk factor for death. In 2021, 8.1 million deaths worldwide could be attributed to air pollution, IQAir said.
Exposure to concentrated micrograms of an air pollutant caused about 58% of those deaths, IQAir said. Exposure to micrograms of pollutants can contribute to and exacerbate health conditions including asthma, cancer, stroke and lung diseases. Children may face issues with respiratory and developmental health.
