Local officials are again distributing air purifiers to residents inundated with pollution from the Tijuana River sewage crisis after they botched their first attempt to do so.
The first batch of 400 air purifiers distributed through a lottery system under former District 1 Supervisor Nora Vargas lacked the necessary filters to clean the gases in the air.
Specifically, the first purifiers lacked the necessary potassium permanganate and charcoal to effectively filter toxic gases. A contractor also failed to transfer applicant information to the San Diego County Air Pollution Control District, forcing people to reapply for the purifiers without notification.
But the San Diego County Air Pollution District is now distributing hundreds of air purifiers to the most affected South Bay households. They’ve abandoned the previous lottery system.
The district said that it has received an additional $1 million in funds, enough for approximately 3,400 air purifiers.
“I’ve spoken with many South Bay families who have participated SDCAPCD’s air purifier program, and we deeply appreciate their commitment to providing essential tools to help alleviate our communities from the impacts of cross-border sewage pollution,” said District 1 Supervisor Paloma Aguirre in a statement.
County officials said they are committed to working with the Air Pollution Control District on to seek additional funding for air purifiers, which they said provide critical relief by improving indoor air quality and reducing exposure to harmful pollutants..
Diane Castañeda, a spokesperson for the county, advised residents to limit outdoor activities in the most affected areas, especially during rain events or when air quality monitors indicate a spike in contaminants. She said it’s best during those times to remain indoors with windows and doors closed.
“Unfortunately, these are the options right now,” she said.
The renewed effort coincides with other progress protecting residents.
Last week, the U.S. Environmental Protection Agency announced a new agreement with Mexico to plan for wastewater infrastructure to accommodate future population growth in Tijuana.
And on Wednesday, State Sen. Steve Padilla introduced a bill to update state standards for hydrogen sulfide. That’s the “rotten egg” gas that sewage in the river produces, which can cause headaches, nausea, other ailments and long-term health problems.
California’s hydrogen sulfide standard has not been updated since 1969. The bill would require the California Air Resources Board to review and potentially tighten the decades-old standards.
Lawmakers say they hope to improve conditions for workers exposed to gases and hold U.S. companies accountable for their role in the binational pollution.
County officials will conduct an health study to measure effects of Tijuana River pollution, and are making plans to remove a pollution hot spot in Imperial Beach.
Academics, scientists and nonprofit organizations continue to test air, water, and soil quality at “hot spots” along the Tijuana River and the Pacific Ocean coastline, and throughout the river valley.
According to San Diego Coastkeeper, which sampled four sites in the Tijuana River Valley, at least 40 toxic metals and chemicals have been found in the water since November 2024, in addition to extremely high levels of E.coli at all testing sites, sometimes hundreds of times past safe limits.
“We are eager to see the U.S. and Mexico’s commitments come to fruition,” said Sarah Davidson, Surfrider Foundation’s Clean Border Water Now Manager, in a statement. “Federal agencies must work together with local agencies, academic institutions, and community-based organizations who are actively monitoring water and air quality.”
Corsi-Rosenthal boxes
While the air purifiers being given out by San Diego County do now contain the proper air filters containing the potassium permanganate necessary for filtration of toxic gases, there are additional do-it-yourself solutions available for those interested in filtering out particulate matter, a particular concern during wildfire season.
A community of DIY and clean air enthusiasts may fill that gap. One favored solution, Corsi-Rosenthal boxes, were created in 2020 in order to provide affordable ways for classrooms and other buildings to that typically contain a lot of people to filter viruses and particulates from the air.
They won’t filter out gases like hydrogen chloride, but they will go a long way toward filtering other adulterants from the air, said Jim Rosenthal, co-founder of the Corsi-Rosenthal Foundation and an air filter expert who helped design the open-source boxes along with his colleague, UC Davis engineering dean Dr. Richard Corsi
“When people are near the odor, near the river, they close their windows because it’s a really irritating smell, but when you do that you have poor ventilation and the inside of your house just becomes not a very good place for infectious aerosols,” he said. “And that’s where CR boxes come in.”
The boxes can be built in minutes using duct tape, a box fan, and four or five MERV13 filters. Open-source plans for the boxes can be found here.
“CR boxes are extremely effective on wildfire smoke,” Rosenthal said. “They do a really good job.”
More information about their efficacy can be found here.
