A new state bill could establish different air quality standards for hydrogen sulfide, a noxious gas that has wreaked havoc on communities near the polluted Tijuana River and Salton Sea.
On Wednesday, State Sen. Steve Padilla,D-San Diego, introduced Senate Bill 58 to update the threshold, which has remained unchanged since it was adopted in 1969. The law would require the California Air Resources Board (CARB) to review the status quo during public workshops in communities like South County and the Salton Sea, and consider adopting stricter standards.
“It is unacceptable that the regulatory standard monitoring the very air our families breathe is so woefully out of date, leaving communities at risk,” Padilla said in a statement. “Making this critical change is a long overdue step towards addressing an issue that has been allowed to fester for decades. It is critical that Sacramento finally act to help our community.”
His District 18 includes the Tijuana River and Salton Sea regions.
Hydrogen sulfide occurs naturally in volcanoes and manure pits, and in industrial activities, such as wastewater treatment and paper manufacturing.
The colorless gas, with a distinct rotten-egg odor, is also present in the billions of gallons of untreated sewage from Mexico that travels via the Tijuana River into the Pacific Ocean off the coast of Imperial Beach. Years of neglect and underinvestment in wastewater infrastructure on both sides of the U.S.-Mexico border have led to years of unchecked sewage spills, exposing people to hydrogen sulfide. In the Salton Sea, agricultural runoff has polluted the lake and algal blooms have produced the noxious gas.
People living and working in these two regions have reported headaches, nausea, chronic coughs, skin irritation, fatigue and worsened conditions like asthma.
Earlier this year, scientists studying the Tijuana River sewage crisis released new data confirming that the polluted river water substantially affects air quality.
Their research, led by Kim Prather, an atmospheric chemist at UC San Diego, focused on measuring hydrogen sulfide.
“Our year-long, high-resolution hydrogen sulfide measurements near the polluted Tijuana River — the longest continuous H2S record for any region — show that residents are experiencing chronic levels far beyond existing health standards,” Prather said in a statement.
Scientists’ data found that gas concentrations measured at a river crossing in the Tijuana River Valley frequently far exceeded the state’s one-hour odor control threshold of 30 parts per billion for several hours.
CARB set the hydrogen sulfide threshold at 30 parts per billion for a one-hour average. This means that for every billion parts of air, no more than 30 parts are hydrogen sulfide. In 1981, the state Dept. of Public Health reviewed the scientific literature and concluded that the existing standard was adequate, according to CARB’s website.
The standard was set primarily for odor nuisance. CARB said that “if the standard was based on adverse health effects, it would be set at a much higher level.” Higher standards exist only in occupational settings, where workers’ exposure is limited and they wear protective equipment.
But researchers, advocates, and local doctors have raised concerns about the potential long-term health effects of exposure to low levels of hydrogen sulfide on nearby residents.
Prather said the persistent spikes and elevated daily averages of hydrogen sulfide “are completely missed by the current system of sparse, hourly monitoring. The science is clear: people in the South Bay are routinely exposed to H2S concentrations that fall well outside the protection of today’s regulations.”
She and other researchers said SB 58 would be an important first step in protecting communities, though it’s unclear how an updated standard would guide public health decisions.
The Senate is expected to hear the proposed legislation in January.
