SECTION 1.
The Legislature finds and declares all of the following:
(a) Hydrogen sulfide is a colorless, highly toxic gas with a strong odor detectable at very low concentrations.
(b) The state board adopted a one-hour ambient air quality standard of 0.03 parts per million (30 parts per billion) for hydrogen sulfide in 1969, primarily to address odor nuisances, rather than chronic or long-term public health effects.
(c) Exposure to hydrogen sulfide is associated with headache, nausea, respiratory irritation, nasal symptoms, and neurological effects, and current evidence indicates that chronic exposure can contribute to persistent respiratory and neurological impacts, with heightened susceptibility among children, older adults, and individuals with preexisting health conditions.
(d) The state’s existing hydrogen sulfide standard has not been updated for 25 years, may not consider contemporary health science, cumulative exposure assessments, or community vulnerability, and may also be insufficient in addressing public health impacts near hydrogen sulfide hotspots across the state.
(e) Monitoring data in regions such as the Tijuana River Valley in the County of San Diego and the Salton Sea in the Counties of Imperial and Riverside have shown exceedances of the state hydrogen sulfide standard; however, it is difficult to identify a responsible party that could be subject to plans to attain the standards.Therefore, there is a need for a response framework that can address local needs in response to harmful air quality.
(f) Modern scientific research conducted in the Tijuana River Valley shows that communities near the river experience prolonged and chronic low-level hydrogen sulfide exposures, with concentrations of hydrogen sulfide frequently exhibiting sudden increases above the current state standard in durations of less than one hour. These sudden increases are in part caused by episodic influxes of transboundary pollution and are not captured in the time-averaged concentrations made to compare to the one-hour standard.
(g) Health symptoms associated with exposure to hydrogen sulfide have been reported in the South Bay region and the cities of San Diego and Imperial Beach, and include respiratory and gastrointestinal issues, headaches, fatigue, nausea, skin irritation, and respiratory irritation.
(h) Monitoring data indicate that hydrogen sulfide concentrations near sensitive locations, including Berry Elementary School in the Tijuana River Valley, have exceeded the current standard, demonstrating that children and other vulnerable populations are exposed to elevated levels.
(i) Similarly, communities surrounding the Salton Sea experience frequent elevated and chronic low-level hydrogen sulfide concentrations, caused by anaerobic biological activity, decomposition of organic matter, and shoreline emissions, with recorded levels frequently exceeding the state standard.
(j) These exposures disproportionately affect vulnerable and environmentally overburdened communities, including low-income households, immigrant communities, Latino and tribal populations, and areas already experiencing elevated rates of respiratory and other health conditions, exacerbating existing health inequities.
(k) The Office of Environmental Health Hazard Assessment indicates that chronic exposure to hydrogen sulfide at levels below the current one-hour standard can adversely affect human health.
(l) Furthermore, factors such as concentration averaging times, local and regional climate, and indoor versus outdoor exposure should be considered in assessing concentration levels and their impacts to public health.
(m) Thus, the Legislature recognizes a need to develop additional threshold levels for hydrogen sulfide that consider these factors in conjunction with local agency response to address public health issues.