South Bay Residents Breathe Easier as 10,000 Air Purifiers Deployed Against Toxic Odors
A critical public health initiative has delivered over 10,000 air purifiers to homes in San Diego and Imperial Beach, offering relief from the persistent and harmful effects of hydrogen sulfide and other airborne pollutants linked to the ongoing Tijuana River Valley crisis.
The San Diego County Air Pollution Control District (SDAPCD) reached a significant milestone this week in its Air Improvement Relief Effort (AIRE) Program, providing a vital layer of protection for communities grappling with noxious and potentially dangerous air quality. The program, launched in February 2025, aims to mitigate the impact of hydrogen sulfide – a gas notorious for its rotten egg smell – and other toxic compounds emanating from the Tijuana River Valley.
With an additional $1 million allocated for continued distribution, the SDAPCD plans to deliver approximately 3,500 more purifiers, extending this crucial support to even more households. But what exactly is causing these dangerous odors, and what are the long-term health implications for South Bay residents?
The Root of the Problem: A Toxic Tide from the Border
The source of the pervasive odors isn’t simply a nuisance; it’s a complex environmental and public health crisis rooted in the ongoing sewage contamination flowing from Tijuana into the United States. For decades, aging and inadequate infrastructure on the Mexican side has resulted in millions of gallons of raw sewage entering the Tijuana River, ultimately impacting air quality in communities like San Ysidro, Imperial Beach, and Chula Vista.
Recent scientific investigations, led by researchers at UC San Diego’s Scripps Institution of Oceanography, UC Riverside, San Diego State University, and the National Science Foundation, have revealed a disturbing pathway for exposure. These studies demonstrate that contaminated river water isn’t just a water quality issue; it’s an air quality issue as well. The research pinpointed a “hot spot” in the Nestor neighborhood where a wastewater discharge pipe was releasing sewage into a confined area, creating turbulence and aerosolizing toxic gases.
“This study reveals a direct airborne pollutant exposure pathway – from contaminated rivers into the air we breathe,” explained Kimberly Prather, a UCSD professor and director of the Center for Aerosol Impacts on Chemistry of the Environment. “For the first time, we’ve shown that poor water quality can profoundly degrade air quality, exposing entire communities to toxic gases and other pollutants.”
The levels of hydrogen sulfide detected were alarmingly high – peaking at 4,500 parts per billion (ppb), a staggering 4,500 times higher than typical urban levels. Even average readings of 2,100 ppb, particularly during nighttime hours when winds are calm, exceed established safety thresholds.
Paula Stigler Granados, an environmental health scientist at SDSU’s School of Public Health, emphasized the severity of the situation. “This level is too high for chronic exposures as 30 parts per billion is already associated with headaches, nausea, respiratory symptoms and other adverse health effects, particularly among vulnerable populations,” she stated. “Framing this as merely an odor issue dangerously understates the real public health risks of repeated exposure to toxic gases at such concentrations.”
Did You Know? Hydrogen sulfide isn’t the only concern. The aerosolized pollutants released from the contaminated water contain over 1,000 different compounds, many of which are toxic and contribute to respiratory problems and other health issues.
The SDAPCD provides an online air quality dashboard to help residents monitor hydrogen sulfide levels and receive alerts when concentrations exceed 30 ppb. The air purifiers distributed through the AIRE program are equipped with activated carbon and potassium permanganate filters designed to reduce hydrogen sulfide and other harmful compounds from indoor air.
But is this enough? What long-term solutions are needed to address the root cause of the pollution and protect the health of South Bay communities? And what can residents do to further safeguard themselves and their families?
Learn more about air purifiers and abatement orders.
Read about the launch of the air purifier program.
Watch: Lawsuit filed against operators of South Bay International Water Treatment Plant
Biden allocates $310M to address the South Bay plant.
Toxic Tide: Study reveals health risks to vulnerable populations.
Watch NBC 7’s special ‘Toxic Tide: The sewage crisis at the border’.
Learn more about the EPA’s work on the U.S.-Mexico Border.
CDC information on Hydrogen Sulfide.
Frequently Asked Questions About the AIRE Program and Hydrogen Sulfide Exposure
Hydrogen sulfide (H₂S) is a colorless gas with a characteristic rotten egg smell. Even at low concentrations, it can cause irritation to the eyes, nose, and throat. Higher concentrations can lead to more serious health effects, including respiratory problems, neurological issues, and even death.
Residents of San Diego and Imperial Beach who live in areas affected by hydrogen sulfide odors are eligible. Specific eligibility requirements and application details can be found on the SDAPCD website.
The air purifiers are equipped with filters designed to remove hydrogen sulfide and other pollutants from indoor air. Surveys conducted by the SDAPCD indicate that most residents who have received purifiers report a reduction in odors.
In addition to using an air purifier, you can limit your exposure by staying indoors when hydrogen sulfide levels are high, closing windows and doors, and avoiding strenuous activity that could increase your breathing rate. Check the SDAPCD air quality dashboard for real-time updates.
Unfortunately, yes. The ongoing sewage contamination from Tijuana is a long-standing problem that requires significant infrastructure improvements and international cooperation to resolve. The AIRE program provides temporary relief, but a permanent solution is needed to protect the health of South Bay communities.
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