County officials said early Tuesday morning that an emergency air monitoring effort focused on the Tijuana River Valley did show an elevated level of hydrogen sulfide, but not hydrogen cyanide as reported Monday by university researchers.
Just one day earlier, research teams studying cross-border pollution held their own news conference indicating that recent monitoring, aided by a special team from Austin, Texas, announced that air monitors had documented hydrogen cyanide levels spiking to 50 parts per million at Saturn Boulevard near Sunset Avenue, a location that is just south of the river and about one mile south of Berry Elementary School.
Given that the National Institute for Occupational Safety and Health considers 50 parts per million the threshold for an exposure that is “immediately dangerous to life and health,” public reaction was immediate.
Nearby schools curtailed outdoor activities, and there were reports Tuesday of parents keeping their children home from school in light of the readings shared by researchers Monday morning.
But the region’s public health department is the ultimate arbiter of what constitutes a legitimate threat to public health and safety.
Dr. Ankita Kadakia, the county’s interim public health director, said that the county hazardous incident response team sent to the area Monday visited the same locations where UC San Diego and San Diego State University research teams said Monday that their monitoring equipment detected potentially harmful concentrations of hydrogen gas.
The “expertly trained” team, she said, took readings during the daytime and at night but did not observe readings that spiked as high as researchers reported.
“DHQ staff have told me since then that, during daytime and nighttime, gas levels for hydrogen cyanide were not elevated,” Kadakia said. “The hazardous incident response team did detect hydrogen sulfide, which has also been reported by the researchers.
“The HIRT team reported that the readings were in average ranges, and that there were some elevations; however, the readings for both hydrogen sulfide and hydrogen cyanide did not suggest imminent danger or threat.”
Why the disparity between what the county found and what researchers found?
Heather Buonomo, interim director of the Department of Environmental Health and Quality, said that there is an ebb and flow to monitoring. Gas concentrations vary over time.
“We weren’t there at the time they got those readings (and) readings are variable,” Buonomo said. “Sometimes they can go up and down based on the river flow.”
Though readouts of what county monitors showed during Monday’s monitoring sessions were not provided for review at Tuesday’s news conference, Buonomo said that her department is working to put the information in a format that would be understandable by the general public for release.
On Tuesday afternoon, the county provided a synopsis of the data that experts collected in the field.
At Saturn Boulevard, the location where hydrogen cyanide readings were said to have jumped to 50 parts per million, levels ranged from zero to 25 parts per million.
“This is below any immediate life and safety threshold given the levels and duration, as it was not observed for a prolonged period of time, and is expected when hydrogen sulfide is present,” the report states.
Readings taken at Godfrey Berry Elementary School and Southwest High School, which are near monitoring sites at Hollister Street and Saturn Boulevard, both measured non-detectable levels of both hydrogen sulfide and hydrogen cyanide.
Nora Vargas, chair of the county Board of Supervisors and a South County resident whose district covers the river valley, said that Tuesday’s news conference was designed to provide accurate information to the public on whether or not the smells filling neighborhoods are dangerous.
“At this time, we’re telling our communities that it’s safe; it smells horrible, but it’s safe,” Vargas said.
Kim Prather, the UC San Diego atmospheric chemist who spoke out Monday about the air quality readings that her team, working with environmental scientists from SDSU and a monitoring team brought in from Austin, did not directly respond when asked to comment on the monitoring results that county workers found.
But she was far from silent on X, the social media site previously called Twitter, posting a thread of eight sequential messages that stood by the findings of the research team.
“Vargas’s claim directly contradicts not only our calibrated, validated hydrogen sulfide data but also the numerous health complaints from South Bay residents, including migraines, respiratory issues, and GI problems,” Prather said.
The statement did not once mention concentrations of hydrogen cyanide but instead focused on hydrogen sulfide, which she said research monitoring efforts showed multi-day measurements “well above the hourly standard of 30 (ppm).”
The county’s report found hydrogen sulfide concentrations of up to 0.5 parts per million at the Hollister Street Bridge and from zero to 16 parts per million at Saturn Boulevard.
It is clear that the county health department and local researchers are operating at arms length holding their own news conferences. And both sides say they have not received full data readouts from the other.
The common ground is the notion that much more should be done to quantify the stench that has made life so unbearable down by the border.
Episodic monitoring of gasses emanating from the river is clearly not the solution. A continuous record of gasses present over time is the only way to truly understand the complex set of conditions that those living nearby are suffering through, especially when hot weather and little wind intensify strong odors, the county said.
But building a network of round-the-clock monitoring stations in the Tijuana River Valley has been an elusive goal.
The San Diego County Air Pollution Control District, despite nearly one year of negotiations, still has installed only two of six planned continuous air monitoring stations planned for the valley. In August, the agency said that myriad paperwork issues has slowed installation and activation of the full network.
County officials were careful to say during Tuesday’s news conference that they do not intend to get involved with ongoing monitoring. Such work, officials emphasized, is in the domain of the Air Pollution Control District.
Kadakia said she recommends that the district hire an environmental toxicologist, “a true subject matter expert who can assist with sensor interpretation and work closely with county public health services.”
Once the sensor network is built out, she added, it should be used to notify valley residents of local air quality. Such a system, she said, could be used to better target assistance to residents.
Vargas, a member of the Air Pollution Control District’s board of directors, said she plans to advocate for such initiatives at the air quality board’s next regular meeting scheduled for Thursday.
“It shouldn’t be this way; people north of the 8 are not waking up every day and trying to figure out if they can go outside and play,” Vargas said. “That’s not fair, it’s not OK for South County.”
Years of negligence and underinvestment in wastewater treatment plants by both countries have led to unprecedented levels of sewage and trash spills, impacting people’s health and local economies. Major repairs are under way on both sides of the U.S.-Mexico border, but substantive relief is still years away.