Every spring, the American Lung Association publishes its State of the Air report — a county-by-county ranking of air quality across the United States. This year's edition delivered a number that should alarm every resident of this region: San Diego County ranked 5th worst in the nation for short-term particle pollution, and 7th worst for ozone.
One year prior, the county ranked 59th for particle pollution. That's not a gradual decline. That is a collapse.
Particle pollution — fine particulate matter small enough to penetrate deep into the lungs — is linked to respiratory disease, cardiovascular problems, and premature death. It is not an abstract environmental metric. It is the stuff in the air your children breathe walking to school. It is what lands in your lungs when you open your back door on a bad morning.
Ozone at ground level, formed when vehicle emissions and industrial pollutants react in sunlight, triggers asthma attacks, inflames airways, and causes long-term lung damage. San Diego ranking 7th worst in the country for ozone means this is not a marginal, edge-of-the-threshold problem. It is a serious, documented public health failure.
Where Does the Sewage Fit In
Wildfires are the dominant driver of particle pollution spikes across Southern California, and the State of the Air report reflects that reality. The 2025 Los Angeles fires contributed significantly to the regional numbers. San Diego County has its own wildfire exposure. These are real contributors and the report doesn't shy away from them.
But the Tijuana River sewage crisis is also part of this picture — and it is the part that most news coverage underweights.
Untreated and partially treated sewage flowing north from Tijuana across the international border doesn't just contaminate water. It produces hydrogen sulfide, ammonia, and volatile organic compounds that degrade air quality in the immediate area. It generates aerosols containing pathogens and fine particulate matter. It creates the conditions for ongoing, chronic low-level air pollution in Imperial Beach, San Ysidro, and adjacent communities — on top of the broader regional particle pollution problem the new report documents.
"Residents in the most affected neighborhoods are being exposed to sewage-derived pollutants on top of an already worsening regional air quality baseline. The cumulative exposure is the issue."
The communities living closest to the Tijuana River — the ones already breathing the highest concentrations of sewage-derived compounds — are now also living in a county that ranks among the most particle-polluted in the United States. These are not separate problems that happen to coexist. They compound each other. Residents in the most affected neighborhoods are absorbing cumulative exposures that the county-level air quality ranking, by itself, does not capture.
What the Rankings Actually Mean
The State of the Air report measures unhealthy air days — days when pollution levels exceed federal health standards. A county ranked 5th worst nationally means residents in that county experienced among the highest number of days per year with air quality that the EPA's own standards classify as unsafe.
These are not standards set by environmental advocacy groups. They are federal thresholds established by the EPA under the Clean Air Act. Exceeding them is a legal and regulatory matter, not just a health concern. And San Diego is now, by that measure, one of the most dangerous counties in the country for air quality.
For context: the counties that typically cluster at the top of the worst-air lists are in California's Central Valley — Kern, Fresno, Kings. These are agricultural and industrial counties with decades of documented air quality failures. San Diego's appearance near the top of that list in 2026 is not business as usual. It is a significant deterioration that demands a response.
San Diego County's particle pollution ranking jumped 54 places in a single year — from 59th to 5th worst in the nation. Communities along the Tijuana River corridor face the highest cumulative exposure in the county.
The Infrastructure Failure That Isn't Being Fixed
The Tijuana River sewage crisis has a known, specific set of causes. The South Bay International Wastewater Treatment Plant — built to process cross-border sewage flows — has been chronically underfunded and has operated over capacity for years. The Saturn Boulevard Pipe Extension, a key piece of infrastructure designed to collect and redirect flows that would otherwise reach the river, has been in a state of disrepair. Upstream infrastructure failures on the Mexican side of the border continue to send millions of gallons of untreated sewage toward the international line.
None of this is unknown. It has been documented by federal agencies, reported on by journalists, raised in Congressional hearings, and litigated in federal court. The International Boundary and Water Commission, the EPA, the State Water Resources Control Board, and elected officials at every level of government are aware of the problem.
And yet the flows continue. The plant remains overwhelmed. The pipe extension remains unrepaired.
A county that just ranked 5th worst in the nation for particle pollution cannot afford to treat a chronic, documented sewage contamination problem as a background issue. The communities most exposed to that sewage are the same communities sitting at the bottom of an already-worsening air quality baseline. The cumulative health burden is real and it is growing.
What You Can Do
The complaint tool on this site was built for exactly this moment. Every report you file — documenting the smell, the headaches, the days you couldn't open your windows — goes directly to the officials responsible for this failure. Not to a general inbox. Directly to elected representatives, agency directors, and environmental journalists who have the power to act or the platform to report.
A county ranked 5th worst in the nation for air quality, with a chronic sewage crisis as one of its contributing factors, cannot continue to be treated as a local nuisance. It is a public health emergency. Document it like one.
File a report. Today.
One minute. Your neighborhood, the conditions, any symptoms. It goes directly to the people whose job it is to fix this — and who haven't.
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