IQAir, a Swiss-based technology company that specializes in air quality monitoring and purification, released its 8th annual World Air Quality Report on March 24. The report found that San Antonio recorded an average annual PM2.5 concentration of 8.2 micrograms per cubic meter in 2025, a level that remains nearly twice the World Health Organization’s guideline.

PM2.5 refers to fine particulate pollution that is small enough to enter the lungs and bloodstream, and long-term exposure has been linked to respiratory and cardiovascular health issues, according to the United States Environmental Protection Agency.

Despite its high ranking, San Antonio’s air quality is gradually improving, according to the report. The 2025 measurement marks the third consecutive year the city has recorded a decrease in particle pollution concentrations, a spokesperson for IQAir told MySA.

And, San Antonio isn’t alone in this. Fort Worth was the ninth-most-polluted city in the country, though pollution levels there declined slightly. Austin and Houston also experienced decreases in PM2.5 concentrations compared with previous years.

Meanwhile, dust storms dramatically worsened air quality in West Texas. Historic dust storms in El Paso triggered a 46% increase in PM2.5 levels, making it the most polluted major city in the United States, according to IQAir. Southeast Los Angeles, California, was the most polluted region in the United States. Seattle, Washington, was the cleanest major U.S. city. 

For this year’s report, IQAir analyzed data from monitoring stations across 9,446 cities in 143 countries, regions and territories. The report defines “major cities” as the 25 most populous cities in the country.

“The World Air Quality Report reveals two competing realities: an air pollution crisis and the rise of communities, scientists and data working to meet the challenge,” Dr. Aidan Farrow, senior scientist for Greenpeace International, stated in the report. “In 2025, familiar culprits like industrial agriculture, wildfires and fossil fuels left their mark in the data collated by IQAir worldwide. This open, transparent data is an essential tool for holding polluters accountable and securing a healthy environment for everyone.”