A day after scientists sounded alarms about elevated levels of toxic gasses in the Tijuana River Valley, San Diego County Supervisor Nora Vargas tried to ease concerns by saying the air quality is no longer a threat to public health.
"I want to reassure everyone that this is not an imminent threat, and it's safe to be outside and attend school,'' said Vargas, who is chairperson of the County Board of Supervisors. "Our county experts are actively gathering public health data and conducting research to provide the most accurate information.”
On Monday, researchers from San Diego State University (SDSU) and UC San Diego reported high levels of hydrogen sulfide and hydrogen cyanide — which can have a rotten egg smell — in South Bay areas near the watershed. This led members of San Diego County’s Congressional delegation to again call for a state of emergency.
In response, Vargas said the San Diego County Hazardous Incident Response Team (HIRT) and researchers from SDSU tested the gas levels. The new testing data "does not indicate any immediate public safety concerns," Vargas said in a statement.
Dr. Kimberly Prather, UCSD's director of the Center for Aerosol Impacts on Chemistry of the Environment, leads a team of researchers studying the impact of the ongoing sewage pollution crisis in the region.
Prather said Monday the air quality levels they recorded over the weekend were so dangerous that she had her team evacuate the area.
"As you know, I feel strongly about solving this problem, but cannot in good conscience continue to put my own people at this level of risk," Prather wrote in an email to colleagues.
On Tuesday, Prather criticized Vargas’ claims minimizing the pollution’s impact on public health.
She published a series of posts on social media calling Vargas’ statements "misleading" and contradictory of the science. She also called into question San Diego County’s research methods by calling them, "an unverified set of measurements from an unknown location."
“It’s deeply concerning that a public official trusted by the community to protect their health would make such a misleading statement,” Prather wrote.
San Diego County officials did not release the results of their air readings on Tuesday but promised to make them available soon.
"The readings for both hydrogen sulfide and hydrogen cyanide did not suggest imminent danger or threat,” said Interim Public Health Officer Dr. Ankita Kadakia. “However, the fact that community members are living in conditions with a strong odor is concerning.”
Kadakia said people impacted by the odor should shut their windows, avoid prolonged outdoor exposure and turn on their air conditioning units.
Officials didn’t say why their readings no longer showed dangerous levels of toxic gas, or whether those levels could come back in the future.
On Monday, Democratic members of San Diego’s congressional delegation — Juan Vargas, Sara Jacobs, Scott Peters, and Mike Levin — said toxic gasses were risking the health of South Bay residents.
"We write to reiterate our request for a State of Emergency in light of new findings that alarming levels of noxious gas are emanating from the Tijuana River," they wrote in a joint letter to President Joe Biden and Gov. Gavin Newsom. "Recent data has made it clear that these fumes are causing an immediate and serious threat to the health and safety of residents of South San Diego, and our community needs additional support."
According to Prather's team, the high levels of gasses are being trapped by the heat wave the region is experiencing. As a result, the odors and gasses are significantly worse than usual, despite lower river flows.
"At one site, there was a measurement of 10 parts per million of HCN, which is the Occupational Safety and Health Administration's (OSHA) limit of exposure for workers with personal protective equipment," the congressional delegation wrote. "Another site had a reading of 50 parts per million of HCN, which is the highest level that researchers' meters could measure."
Prolonged exposures to these gasses can lead to headaches, nausea, nervous system issues and even death. South Bay schools had limited outdoor exposure for students, and the San Diego County Air Pollution Control District (APCD) at the time recommended nearby residents stay inside.
Vargas said that on Thursday she will work with the APCD and California Air Resources Board to attempt to create real-time dashboards the public can use to monitor air quality. She said she will also ask the U.S. Environmental Protection Agency for funding to expand the distribution of air purifiers to impacted residents.
