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Pollution from the Tijuana river affects air quality in San Diego, finds study

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Pollution from the Tijuana river affects air quality in San Diego, finds study


Coastal environments are extremely dynamic. Pollutants in the land and water can become aerosolized and inhaled by residents of coastal communities. Credit: Adam Cooper / UC San Diego

The 120-mile Tijuana River flows from Baja California into the United States and discharges millions of gallons of wastewater—including sewage, industrial waste and runoff—into the Pacific Ocean every day, making it the dominant source of coastal pollution in the region.

Wastewater pollution has been an ongoing problem for decades and is so severe that the nonprofit environmental group American Rivers recently named the Tijuana River America’s second most endangered river.

A new study from the University of California San Diego examines how pollutants in wastewater travel and are transmitted in the atmosphere through coastal aerosols.

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In the study, researchers found that a mixture of illicit drugs, drug metabolites, and chemicals from tires and personal care products aerosolize from wastewater and are detectable in both air and water. The results appear in Science Advances.

The paper’s lead author, Adam Cooper, collected samples from the air and water at various points along the coast of San Diego County, including the U.S.-Mexico border, Imperial Beach and the Scripps Institution of Oceanography in La Jolla.

Cooper, who graduated last spring with a doctorate in chemistry, was a member of Assistant Professor of Chemistry and Biochemistry Jonathan Slade’s group, and collected the samples as part of a field study with Distinguished Professor of Atmospheric Chemistry Kimberly Prather’s lab.

Prather, who holds a joint appointment at Scripps Oceanography and the Department of Chemistry and Biochemistry at UC San Diego, had been studying the air pollution impacts of the Tijuana River for several years. Cooper was able to join her team’s comprehensive sampling campaign across multiple sites from January to March of 2020.

Even though the samples were taken in 2020, the findings are still relevant because little has changed in how sewage released from the river is processed. In fact, pollution from the river has been an ongoing problem for more than 50 years.

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“The Tijuana River region is a very dynamic environment with implications for public health, environmental policy and international relations between the United States and Mexico,” stated Cooper.

“Ours is one of the most comprehensive studies to date investigating water-to-air transfer of these pollutants.” The study looked at two aspects of wastewater pollution: the source and the concentration of pollutants along the San Diego County coastline.

To determine the origin of the pollutants, Slade’s lab used a compound they knew came from sewage: benzoylecgonine (BZG), a stable metabolite of cocaine, primarily produced when people use cocaine and then excrete it in urine.

They found that after rainfall, BZG levels in Imperial Beach ocean water spiked in correlation with increased Tijuana River flows, while BZG levels in aerosols spiked in correlation with enhanced sea spray aerosol emissions.

Correlating 11 other pollutants to BZG in aerosols allowed the team to determine which ones behaved similarly in the environment and likely originated from the same wastewater source. The results showed a high correlation between BZG; methamphetamine; octinoxate, a UV filter used in sunscreen; and dibenzylamine, a compound used in tire manufacturing.

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The second part of the study measured pollutant concentrations along the coastline in the water and air. Overwhelmingly, they found that these pollutants were higher in the Tijuana River water than in the ocean, and higher in the water and aerosols in the Imperial Beach region than in La Jolla.

Although the amounts of some pollutants, like cocaine, were minuscule, others were more prominent, like octinoxate, which can break down into more toxic components.

In some cases, the octinoxate levels were comparable to measurements made directly above wastewater treatment plant vats, meaning that in some ambient conditions at the coast, the concentrations of pollutants that people are inhaling can be comparable to a worker at a wastewater treatment plant.

“It’s been shown that octinoxate can degrade DNA when exposed to light,” stated Slade. “And if it’s in these tiny aerosols we’re breathing in, it can get deep into our lungs and pass into our bloodstream. That’s very concerning, especially considering the high levels at which we found it in the air.”

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The study shows that the closer you are to the Tijuana River, the more likely you are to be exposed to the pollutants it carries, even though the amounts are still relatively small—on the scale of tens of nanograms per hour. This may not seem like much if your exposure is limited to a few hours, but residents living close to the border are inhaling these chemicals over years, even decades.

Many residents have complained of respiratory illness, insomnia and headaches, and several San Diego beaches have been closed almost continuously for the last three years because of high levels of bacteria from wastewater runoff.

Although the paper doesn’t draw any conclusions about the detrimental effects on the environment or human health, Slade and Cooper emphasize the need for more research, better infrastructure and cross-border collaboration.

“Often the sewage crisis is considered a water issue—and it is—but we show that it’s in the air too. Truthfully, we don’t yet know the acute health effects,” stated Slade. “But the numbers we report can be incorporated into models to help us better understand what we’re breathing in and how much we’re exposed to.”

Cooper was so influenced by his work at UC San Diego that he is now a Science and Policy Technology Fellow with the California Council on Science and Technology, working with State Senator Ben Allen.

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“The solutions to the cross-border sewage crisis aren’t constrained by technical challenges,” stated Cooper. “They’re constrained by political challenges and policy issues. We have to motivate decision-makers to make the right investments.”

In addition to better infrastructure, more public awareness is crucial to improving the region’s water and air quality, including understanding the downstream effects of the products we use, such as sunscreens and tires.

“Although our study focuses on the Tijuana River, there are other notable sources of wastewater and pollution run-off in Southern California, including wastewater treatment outfalls, the San Diego River and the Los Angeles River,” said Slade, who also noted that “turbulence in rivers and streams may aerosolize wastewater, requiring further study.”

Coastal port environments are extremely dynamic and complex, but these pollution issues are not relegated just to the San Diego-Tijuana region. They pose a global hazard.

An estimated 80% of all global wastewater is untreated. Of the portion that is treated, many plants remove bacteria, but not chemical pollutants. These chemicals remain in the water, which is released into rivers, lakes and oceans, traveling around the world through waterways and in the atmosphere.

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“The global surge of untreated wastewater entering lakes, rivers and oceans poses a growing health threat. Aerosolization of this polluted water exposes billions of people through airborne transmission, reaching far beyond those in direct contact and impacting countless others who inhale contaminated air that can travel for many miles,” stated Prather.

“We are continuing our studies in this region to better understand the short and long-term health impacts of inhaling this newly identified source of airborne pollution.”

More information:
Adam Cooper et al, Identifying Wastewater Chemicals in Coastal Aerosols, Science Advances (2025). DOI: 10.1126/sciadv.ads9476. www.science.org/doi/10.1126/sciadv.ads9476

Provided by
University of California – San Diego

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Pollution from the Tijuana river affects air quality in San Diego, finds study (2025, May 28)
retrieved 28 May 2025
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Oregon State Dismantles San Diego 83-49

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Oregon State Dismantles San Diego 83-49


The top teams in the West Coast Conference are jockeying for position in the standings as the regular season draws to a close, and the Oregon State women took care of business Thursday night, blowing out the San Diego Toreros 83-49 to move to 21-9 on the season, and 13-4 in conference play.


Oregon State’s Tiara Bolden Grabs WCC Honor After 44 Points Over Two Games

The Toreros have been a basement dweller in the conference for the last few seasons, so this result isn’t surprising, though it’s magnitude is a bit eye-raising. The Beavers wasted no time putting San Diego into a hole, opening the first quarter on an 8-0 run that Tiara Bolden and Kennedie Shuler getting involved early. Oregon State held a 14 point, 26-12 lead after one.

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The second quarter wasn’t as lopsided, but San Diego wasn’t able to make much headway into the Beaver lead. Six points from Olivia Owens kept San Diego within shooting distance, but defensive pressure from Kennedie Shuler and strong rebounding from Lizzy Williamson kept the Toreros under control. Oregon State ended the first half up by 13, 40-27.

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Oregon State Dominates Cougars in 79-51 Blowout

Oregon State tightened their grip in the third. While Olivia Owens and Kylie Ray managed to give the Toreros some hope early in the quarter, Oregon State went on a run late in the period to get their lead to 21 at the highest. San Diego finally snapped the Beaver hot streak, but a three from Kennedie Shuler ended the quarter in a 61-43, 18 point Beaver lead.

The bottom seemed to fall out of San Diego in the fourth, with the Toreros only putting six points on the board. Tiara Bolden and Kennedie Shuler kept the points flowing for the Beavers, while Lizzy Willilamson continued to dominate the boards. A layup with an and one from Elisa Mehyar were the last Beaver points of the game, giving Oregon State a 34 point, 83-49 win.


Oregon State Takes Down Portland 64-54 in Season Saving Game

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It was a good night for several Beavers, with Kennedie Shuler once again leading the team in scoring. She finished the night with 22 points, four rebounds, three assists, two blocks and two steals. She can do just about everything on the court.

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Tiara Bolden continued her hot streak with a 17 point night, along with four rebounds and four assists. Jenna Villa added 14 points, one rebound and one assist. Lizzy Williamson added another double double to her resume, with 10 points and 12 rebounds.


Oregon State’s Winning Streak Ends With 55-51 Loss to LMU

There’s one last item on the agenda for Oregon State, a season-closing meeting with the Loyola Marymount Lions Saturday at Gill Coliseum. The Lions handed Oregon State their first WCC loss of the season back in January, so getting some revenge before the conference tournament would be a good statement from the team. Tip off is set for 1 PM PT.



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Live in San Diego? The city wants your feedback on the next fiscal budget in a survey

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Live in San Diego? The city wants your feedback on the next fiscal budget in a survey


Mayor Todd Gloria sought the public’s feedback Thursday in shaping San Diego’s 2026-27 fiscal year budget, as the city launched a digital survey to help determine which programs and services are prioritized and which are reduced.

The survey is available at datasd.typeform.com/2027budget.

Officials will use responses in crafting the new budget, which takes effect on July 1. The City Charter deadline to release a draft budget is April 15, “allowing ample time for resident feedback to be considered during budget discussions,” officials said.

Gloria said that the city has already “closed hundreds of millions of dollars of a longstanding structural deficit, but we are not done. The next budget will require even tougher choices, and I want to be clear with residents: We will not be able to do everything we might like to do.

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“I’m asking San Diegans to take a few minutes to tell us what matters most to them, and what they’re willing to forgo, as we build next year’s budget,” he added.

The five-minute survey is open to residents living within San Diego city limits. Those without home computer access can fill out the survey at any city library.

According to Gloria’s office, the city’s projected deficit is $120 million for the next budget, which the city is required by law to keep balanced.

In addition to asking what residents’ top priorities are, the survey asks if the city “should generate more revenue to protect services.”

Offered in English and Spanish, the survey is available until the start of May.

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Officials said residents can also sound off on the budget process by attending City Council budget meetings either in person or via Zoom.

Council members will discuss the budget during their March 10 meeting, which starts at 6 p.m. at the City Administration Building downtown.

Public library locations can be found at sandiego.gov/public- library/locations.



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San Diego State beats Utah State, moves into first-place tie

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San Diego State beats Utah State, moves into first-place tie


This time, Reese Dixon-Waters watched his step.

And the senior forward’s game-high 20 points helped San Diego State get back in step in the Mountain West, leading the Aztecs to an 89-72 victory over Utah State at Viejas Arena.

“I was aggressive from the start,” Dixon-Waters said after SDSU ended a two-game losing streak and, more importantly, the Aztecs (19-8, 13-4 MW) moved into a first-place tie with the Aggies (23-5, 13-4) with three games remaining in the regular season.

“Probably our most complete game of the season,” said SDSU coach Brian Dutcher, whose team rebounded after last week’s losses to Grand Canyon and Colorado State. “We did what we had to do. We fought through a tough stretch of two really hard losses, and we got back on the winning track. … So our fate is in our hands.”

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The Aztecs played with the “urgency” junior forward Miles Byrd said was necessary to finish out the regular season right. They avenged a 71-66 loss to the Aggies along the way.

Miles Heide #40 of San Diego State and Adlan Elamin #35 of Utah State vie for the rebound during their game at Viejas Arena on Wednesday, Feb. 25, 2026 in San Diego, California. (Meg McLaughlin / The San Diego Union-Tribune)

When SDSU played at Utah State last month, the Aztecs could have excused their five-point loss on any number of things.

Altitude: Logan’s Dee Glen Smith Spectrum is 4,783 feet, which leaves opponents fatigued and fighting for air in a game’s waning minutes.

Injuries: The absence of SDSU sophomore forward Magoon Gwath (hip) and freshman guard Elzie Harrington (lower leg) left the Aztecs without two starters.

Bad luck: Dixon-Waters was closing in on a career-high in scoring when he stepped on a teammate’s foot with 13 minutes left. He made only one more basket thereafter (though had a game-high 19 points).

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An old classic: The dog ate their game plan.

There were no excuses needed in Wednesday night’s victory at Viejas, where the Aztecs breathed in the sea-level air, welcomed Gwath and Harrington back to the starting lineup and watched Dixon-Waters provide the first-half spark.

The Long Beach native scored 15 points — including 3-for-6 on 3-pointers — as SDSU built a 46-33 halftime lead. He had 10 straight points during a 2 1/2-minute stretch when the Aztecs turned a two-point lead into 29-21 advantage. And they never looked back.

“The hungry team usually wins,” Utah State coach Jerrod Calhoun said. “The tougher team usually wins. I think you would agree. You watched that with your own eyes. They were just a tougher team tonight, more prepared. …

“We had no want-to on the defensive end. And you’re not coming into Viejas, beating these guys with your offense. We’ve never beaten them with our offense. It’s always been our defense.”

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Gwath had seven points in the first half, including a buzzer-beating three-pointer. After the ball kissed off the glass and went in, the 7-footer smiled broadly. (Maybe because he didn’t call bank.)

Pharaoh Compton #5 of San Diego State celebrates after a dunk against Utah State during their game at Viejas Arena on Wednesday, Feb. 25, 2026 in San Diego, California. (Meg McLaughlin / The San Diego Union-Tribune)
Pharaoh Compton #5 of San Diego State celebrates after a dunk against Utah State during their game at Viejas Arena on Wednesday, Feb. 25, 2026 in San Diego, California. (Meg McLaughlin / The San Diego Union-Tribune)

The Aztecs picked up where they left off in the second half, this time with Byrd getting into the act. He was scoreless in the first half, but hit a 3-pointer in the first minute back on the floor. Moments later, he followed with a layup. That made it 51-33 on the way to a 24-point lead.

There was a concious effort about “not letting up,” SDSU sophomore forward Pharaoh Compton said. “Don’t let our foot off the gas because we know a lot of times this year we let our foot off the gas going into the second half.”



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