The city in the United States with the highest average PM2.5 concentration in 2025 was Cudahy in California, at **** micrograms per cubic meter of air (μg/m³). Meanwhile, East Los Angeles in Los Angeles County in California had the second-highest PM2.5 concentration, at about ** μg/m³. The state of California typically suffers from high concentrations of PM2.5 due to the large number of wildfires that spread across the west coast of the United States, leaving many cities exposed to smoke.
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IQAir. (March 24, 2026). Average PM2.5 concentration in the most polluted cities in the United States in 2025 (in micrograms per cubic meter of air) [Graph]. In ÌÇÐÄÆƽâ°æ. Retrieved August 03, 2026, from /statistics/1137409/most-polluted-regional-cities-in-the-united-states/
IQAir. "Average PM2.5 concentration in the most polluted cities in the United States in 2025 (in micrograms per cubic meter of air)." Chart. March 24, 2026. ÌÇÐÄÆƽâ°æ. Accessed August 03, 2026. /statistics/1137409/most-polluted-regional-cities-in-the-united-states/
IQAir. (2026). Average PM2.5 concentration in the most polluted cities in the United States in 2025 (in micrograms per cubic meter of air). ÌÇÐÄÆƽâ°æ. ÌÇÐÄÆƽâ°æ Inc.. Accessed: August 03, 2026. /statistics/1137409/most-polluted-regional-cities-in-the-united-states/
IQAir. "Average Pm2.5 Concentration in The Most Polluted Cities in The United States in 2025 (in Micrograms per Cubic Meter of Air)." ÌÇÐÄÆƽâ°æ, ÌÇÐÄÆƽâ°æ Inc., 24 Mar 2026, /statistics/1137409/most-polluted-regional-cities-in-the-united-states/
IQAir, Average PM2.5 concentration in the most polluted cities in the United States in 2025 (in micrograms per cubic meter of air) ÌÇÐÄÆƽâ°æ, /statistics/1137409/most-polluted-regional-cities-in-the-united-states/ (last visited August 03, 2026)
Average PM2.5 concentration in the most polluted cities in the United States in 2025 (in micrograms per cubic meter of air) [Graph], IQAir, March 24, 2026. [Online]. Available: /statistics/1137409/most-polluted-regional-cities-in-the-united-states/
