The tijuana river crisis is no longer only a smell problem for South Bay families. New numbers from UC San Diego’s Airborne Institute show hydrogen sulfide readings climbing to dangerous levels, with some recent measurements reaching 150 times the state’s safety standard and one Sunday reading topping 2, 000 parts per billion.
Verified fact: The state limit is 30 parts per billion. Analysis: For residents in Imperial Beach, the issue has shifted from chronic nuisance to daily displacement, as some now say they cannot stay in their homes. The tijuana river has become the center of a public health dispute that is now being described by researchers and local officials as a crisis with no simple fix.
Why are residents saying they cannot stay in their homes?
Sonia Mayorga, a long-time Imperial Beach resident, says she and her husband are being pushed out by the air inside and around their home. She said they feel severe symptoms when they are in Imperial Beach, and those symptoms fade after they leave. Mayorga described the situation plainly: “We have a beautiful home, with my family over there, we can’t go back because it’s so toxic. ”
Her account matches the broader warning from researchers that the problem is now reaching breaking point for some South Bay residents. Symptoms linked to hydrogen sulfide exposure can include headaches, nausea, and nose and throat irritation. San Diego State Environmental Professor Dr. Paula Granados said in 2024 that once the readings spike, dangerous health conditions can follow.
Verified fact: UC San Diego’s Airborne Institute recorded the most recent dangerous readings, and the last time the university measured levels this high was September 2024. Analysis: That makes the latest surge significant not just because of the number itself, but because it suggests the crisis is returning with the same severity after months of concern.
What do the new readings actually show?
The clearest warning sign came from the numbers. District 1 Supervisor Paloma Aguirre shared recent UC San Diego readings showing that on April 5, hydrogen sulfide levels stayed above the state safety standard overnight for the first time. Aguirre called it “a milestone nobody wants” and said, “We’re entering a new era of crisis. ”
Then came an even more alarming reading. On Sunday, April 12, the Airborne Institute measured hydrogen sulfide at more than 2, 000 parts per billion at one point. UC San Diego Professor Dr. Kimberly Prather said those levels are higher than what would be seen at wastewater treatment plants.
Prather added that workers at treatment plants would normally wear full protective equipment in those conditions, while the community has no such protection. She also said hydrogen sulfide is only one of thousands of harmful gases detected by the research team. This detail matters because it shows the air quality concern is not limited to a single pollutant, even though hydrogen sulfide has become the clearest public marker of danger.
Verified fact: The state’s safety standard is 30 parts per billion. Analysis: Readings at 150 times that level, and then above 2, 000 parts per billion, make the official threshold look less like a warning line and more like a limit that has been repeatedly overwhelmed.
Who is demanding action now?
Dr. Kimberly Prather has pushed the issue onto the governor’s desk. In a letter to California Gov. Gavin Newsom, she called for a state of emergency over an air quality crisis. She wrote that her team’s continuous atmospheric monitoring represents “an air quality crisis with no parallel anywhere else in the United States” and said the link to health damage on people and the environment is proven. Prather urged Newsom to use his authority before leaving office.
Supervisor Aguirre, meanwhile, is working ahead with some of the candidates for governor. That suggests the political response is already spreading beyond immediate containment and into the next phase of state leadership. The difference between these two efforts is important: Prather is pressing for emergency action now, while Aguirre is also trying to keep the issue on the agenda for whoever follows.
The residents, scientists, and local officials featured here are speaking from different positions, but their message points in one direction. The problem is worsening, the air is still dangerous, and the community does not have a credible way to protect itself from the gases being measured near homes.
What does the crisis mean when viewed together?
Placed side by side, the facts show a widening gap between official standards and lived reality. The state limit is 30 parts per billion, yet the latest readings have moved far beyond it. Researchers are documenting spikes that they say resemble or exceed wastewater treatment conditions. Residents are describing symptoms severe enough to force them out of their homes. And local leaders are publicly saying the situation has entered a new era.
Verified fact: The readings, the symptoms, and the emergency appeal all come from named institutions and officials: UC San Diego’s Airborne Institute, San Diego State Environmental Professor Dr. Paula Granados, UC San Diego Professor Dr. Kimberly Prather, and District 1 Supervisor Paloma Aguirre. Analysis: Together, they show a crisis that is not being experienced equally. Some people can leave for a few days and return, while others are facing the prospect of moving away entirely.
What is not being resolved is as important as what is being measured. Residents are still living with the sewage stench. Scientists are still documenting harmful gases. And public officials are still debating the scale of response needed. Until that gap closes, the tijuana river crisis will remain not just an environmental failure, but a test of whether the state will treat toxic air as an emergency before more families decide they cannot go back.
