Only Seven Countries Meet WHO Air Quality Guidelines on PM2.5: Report

Most countries around the world have air quality that is worse than the guidelines set by the World Health Organization (WHO), according to the latest World Air Quality Report by IQAir.

The seventh-annual World Air Quality Report collected data from 40,000 air quality monitoring stations across 138 countries, territories and regions. The results revealed that only seven countries meet the annual average guideline for fine particulate matter, or PM2.5, of 5 micrograms per cubic meter (5 µg/m3) as set by WHO. The countries that meet this target include Australia, Bahamas, Barbados, Estonia, Grenada, Iceland and New Zealand.

Further, the report found that just 17% of all cities globally meet WHO’s air pollution guidelines with Mayaguez, Puerto Rico topping the list of cities with the cleanest air. The city had an annual average of 1.1 µg/m3 of PM2.5 levels for 2024. 

In terms of regions, IQAir found that Oceania had the world’s cleanest air, with 57% of cities in this region having 5 µg/m3 or less annual average PM2.5 levels.

The report also detailed countries and cities with the poorest air quality levels. The five countries with the worst air quality included Chad with 91.8 µg/m3, Bangladesh with 78 µg/m3, Pakistan with 73.7 µg/m3, Democratic Republic of the Congo with 58.2 µg/m3 and India with 50.6 µg/m3. 

Further, IQAir noted that of the 138 countries, territories and regions surveyed, 126 (or over 91%) surpassed the WHO guideline for fine particulates.

The city with the most polluted air in 2024 was Byrnihat, India, which reached an annual average PM2.5 concentration of 128.2 µg/m3. In the U.S., Los Angeles was the most-polluted major city, while Ontario, California was the most-polluted city of any size overall in the country.

Based on the findings, IQAir highlighted the importance of expanding air quality monitoring sites to collect more data that can inform policies to curb pollution.

“Air pollution remains a critical threat to both human health and environmental stability, yet vast populations remain unaware of their exposure levels,” Frank Hammes, Global CEO of IQAir, said in a statement. “Air quality data saves lives. It creates much needed awareness, informs policy decisions, guiding public health interventions, and empowers communities to take action to reduce air pollution and protect future generations.”

As The Guardian reported, there is no determined safe level of PM2.5. Fine particulate matter can come from fire smoke, smoke from wood-burning stoves or fireplaces, vehicle exhaust, industry processes and more, according to Environment Protection Authority Victoria. Because of the small size of the particles, PM2.5 can enter the lungs and bloodstream. Over time, exposure to high levels of PM2.5 can lead to negative health impacts — including impaired cognitive functioning and reduced lung functioning in children and increased risk of worsening heart disease, increased risk of lung cancer, and impaired cognitive functioning in adults — and has been linked to premature death, as reported by the American Lung Association.

“Air pollution doesn’t kill us immediately — it takes maybe two to three decades before we see the impacts on health, unless it’s very extreme,” Hammes told The Guardian. “[Avoiding it] is one of those preventative things people don’t think about till too late in their lives.”