Riverside and San Bernardino counties remain among the worst places in the nation for air pollution, according to the American Lung Association’s 2026 “State of the Air” report.
The annual report found both counties — part of the Los Angeles-Long Beach metro area — ranked first and second nationally for smog pollution. San Bernardino County ranked first, followed by Riverside County.
The report marks the 26th consecutive year the region has topped the nation for unhealthy ozone levels, according to the American Lung Association.
Residents in both counties experienced more than 100 days of unhealthy smog last year. San Bernardino County recorded 159.2 weighted average ozone or smog days, while Riverside County saw 126.7.
Dr. Afif Al Hasan, a pediatrician with Kaiser Permanente, said ozone pollution is especially dangerous for children because it damages the lungs over time.
“Ozone is a corrosive chemical that attacks our airways and lungs, often likened to a sunburn in the lung,” Al Hasan said. “Very irritating, very destructive to the tissue that it touches.”
The American Lung Association says nearly half of children in the U.S. are breathing unhealthy levels of air pollution, including 7 million children in California. Statewide, more than 8 in 10 Californians live in counties with unhealthy air.
The report measures pollution using data collected between 2022 and 2024 and grades counties based on ozone pollution and short- and long-term particle pollution, commonly known as soot.
Particle pollution can trigger asthma attacks, heart problems, strokes and even lung cancer. Ozone pollution can permanently reduce lung growth in children and increase the risk of respiratory disease later in life.
While the Inland Empire continues to struggle with smog, the Central Valley also ranked among the nation’s worst areas for soot pollution.
Bakersfield ranked as the most polluted U.S. city for annual particle pollution, while Fresno ranked fourth. Visalia and San Diego tied for fifth.
Despite those challenges, the report also found signs of progress.
Seven California communities, including Los Angeles, Bakersfield and Fresno, posted their lowest annual particle pollution levels ever recorded in the report. Sacramento and Redding also saw their fewest unhealthy ozone days on record.
Several coastal communities ranked among the cleanest cities in the country for air quality, including Salinas, Chico, Santa Maria-Santa Barbara and San Luis Obispo-Paso Robles.
But, Will Barrett with the American Lung Association warned that both state and federal actions could reverse decades of progress.
“There is again a slew of bills this year that would preempt local air district programs, that would erode California’s smog check program for passenger cars and for the heavy-duty truck inspection program,” Barrett said.
He also said that federal attacks on California’s Clean Air Act authority could have major public health consequences.
“The most recent estimates indicate that the federal attacks on California’s Clean Air Act authority will lead to over 14,000 deaths, thousands of ER visits and hospitalizations, and health impacts reaching $145 billion,” Barrett said. “Those staggering numbers stand in stark contrast to the progress Californians have enjoyed.”
This is where the Inland Empire ranks for air quality in 2026
Ozone Pollution (Smog)
1. San Bernardino County — 159.2 unhealthy air days in 2025
2. Riverside County — 126.7 unhealthy air days in 2025
Annual particle pollution (year-round soot levels)
7. San Bernardino County — 12.9 DV
10. Riverside County — 12.4 DV
Both counties rank among the worst in the nation for year-round fine particle pollution.
Bakersfield ranked the most polluted U.S. city for annual particle pollution.
Short-Term Particle Pollution
10. Riverside County — 13 unhealthy days
15. San Bernardino County — 10 unhealthy days
Statewide Impact
- 82% of Californians live in counties with unhealthy air.
- 7 million children in California are breathing unhealthy air.
- 33.5 million children nationwide live in areas with failing air quality grades.
