Science
Salton Sea is emitting foul-smelling hydrogen sulfide gas, triggering health concerns
On scorching days when winds blow across the California desert, the Salton Sea regularly gives off a stench of decay resembling rotten eggs.
New research has found that the shrinking lake is emitting the foul-smelling gas hydrogen sulfide more frequently and at higher levels than previously measured.
The findings document how the odors from the Salton Sea add to the air quality problems and health concerns in communities near the lake, where windblown dust drifts from exposed stretches of lakebed and where people suffer from high rates of asthma and other respiratory illnesses.
“The communities around the Salton Sea are on the front lines of a worsening environmental health crisis,” said Mara Freilich, a co-author of the study and assistant professor in Brown University’s Department of Earth, Environmental and Planetary Sciences.
The Salton Sea is California’s largest lake, covering more than 300 square miles in Imperial and Riverside counties. Hydrogen sulfide is released as a byproduct of decaying algae and other organic material in the lake, where accumulating fertilizers and other nutrients from agricultural runoff and wastewater feed the growth of algae.
Hydrogen sulfide, or H2S, is toxic and studies have found that health effects of exposure at certain levels can include dizziness, headaches, vomiting, cough, chest tightness and depression. Although being exposed to high levels in the workplace is a widely known health hazard, less is known about the health effects of chronic exposure to the gas at lower levels.
People who live near the Salton Sea, many of them farmworkers, have complained for years that the stench, which tends to emerge most strongly in August and September, can give them headaches, nausea and nosebleeds.
Freilich and other researchers analyzed existing air-quality data from three monitoring stations maintained by the South Coast Air Quality Management District in Indio, Mecca and the reservation of the Torres Martinez Desert Cahuilla Indians.
They worked with the local nonprofit group Alianza Coachella Valley to install an additional air-quality sensor on a wooden piling protruding from shallow water near the north shore. The sensor has often detected hydrogen sulfide at high levels.
Examining data from different monitoring sites between May 1 and July 25, 2024, they found a striking contrast. Although the monitor on the Torres Martinez reservation detected hydrogen sulfide at levels exceeding the state air-quality standard for only four hours during that time, the sensor over the water found 177 hours with levels above the threshold.
The scientists said their results indicate that a significant portion of the gas that’s being released by the Salton Sea isn’t being measured, even as the stench drifts through the area’s predominantly Latino communities.
“These findings highlight the need for improved air quality monitoring and more effective environmental management policies to protect public health in the region,” the researchers wrote in the study, which was published May 31 in the journal GeoHealth.
The Salton Sea lies about 242 feet below sea level in the Salton Trough, which over thousands of years has cycled between filling with Colorado River water and drying out. The lake was formed most recently in 1905-07, when the Colorado flooded the region, filling the low-lying basin.
In the 1950s and ‘60s, the Salton Sea became a popular destination where tourists flocked to go fishing, boating and waterskiing. Celebrities including Frank Sinatra and Lucille Ball visited the lake during its heyday.
But lakeside communities deteriorated after flooding in the 1970s. Fishing waned as the lake grew too salty for introduced species such as corvina, and people stopped boating as the water quality worsened.
The lake has for more than a century been sustained by water draining off farms in the Imperial Valley, but it has been shrinking since the early 2000s, when the Imperial Irrigation District began selling a portion of its Colorado River water to growing urban areas under an agreement with agencies in San Diego County and the Coachella Valley.
The lake’s level has declined about 13 feet since 2003. Its water is now about twice as salty as the ocean and continues to get saltier with evaporation. Bird populations have declined.
Hydrogen sulfide builds up in the lower, oxygen-deprived layer of water in the lake as decaying algae and other material decompose. During the hottest times of year, a warm upper layer of water forms. Then, when winds churn up the lake, some of the deeper water can rise to the surface and release the stinky gas into the air.
California’s ambient air-quality standard is 30 parts per billion, averaged over one hour. The study found that under certain wind conditions, hydrogen sulfide levels were on average 17 parts per billion higher at the newly installed sensor over the water compared with an existing monitor near the shore.
Sometimes, the sensor detected levels as high as about 200 parts per billion.
People can detect the smell of the gas, however, at levels as low as 1 or 2 parts per billion.
“Residents exposed to hydrogen sulfide are impacted not only in their physical health — experiencing respiratory irritation, headaches and fatigue — but as well in their quality of life,” said Diego Centeno, the study’s lead author, who conducted the research while studying at Brown University and is now a doctoral student at UCLA.
“If you want to be active outside, go on a run or do something, and it smells like rotten eggs, you’d be more inclined not to,” Centeno said. “Especially during summertime, nobody wants to go outside.”
Centeno grew up within sight of the Salton Sea in the low-income community of North Shore. He said he was always fascinated by the immense body of water, not knowing why he never saw anyone bathing or boating in it.
“As water levels continue to decline, if nothing is done, this hydrogen sulfide gas really has the potential to grow,” Centeno said. “So the more we understand, the more we can learn how to mitigate and restore the Salton Sea.”
The researchers said their findings highlight the need for increased air-quality monitoring around the Salton Sea, and for regulators to focus on hydrogen sulfide as a pollutant that affects people’s health.
Freilich said regional water regulators should prioritize setting of water-quality standards for the Salton Sea, a step that could lead to efforts to treat or reduce the nutrient levels of water flowing into the lake.
“The water quality in the sea is affecting the air quality,” she said. “It requires the attention of multiple agencies, because it is something that connects water quality and air quality, which are typically handled separately.”
The South Coast Air Quality Management District, or AQMD, regulates air pollution in the Coachella Valley, including the northern portion of the Salton Sea. In May, the agency installed a fourth monitor for hydrogen sulfide on the northeastern side of the lake.
“This H2S monitoring network is very comprehensive,” said Rainbow Yeung, an AQMD spokesperson, adding that there are currently only a few other monitors reporting such data in the country.
Yeung said in an email that the sensor installed by the researchers is of a different type than the agency’s monitors and “may have higher H2S readings as the location of the sensor is over the source of likely emissions, which can be dispersed and therefore may not be representative of levels experienced by the community.”
AQMD issues alerts whenever hydrogen sulfide levels reach the state standard of 33 ppb at any of the monitoring sites. (Residents can sign up to receive these air-quality alerts at www.saltonseaodor.org.)
The California Office of Environmental Health Hazard Assessment has established a chronic exposure threshold for hydrogen sulfide of 8 parts per billion, a level at which long-term exposure over many years may begin to result in health effects.
The highest annual average concentration at any of the AQMD monitoring sites since 2016 has been 5.5 parts per billion, and annual averages have typically been less than 3 parts per billion, levels at which health effects are not expected, Yeung said.
The water that drains from Imperial Valley farmland and feeds the sea comes from the Colorado River. A quarter-century of mostly dry years compounded by climate change has prompted difficult negotiations among seven states over how to use less water from the dwindling river.
As these talks examine water-saving solutions, Freilich said, policymakers should “account for the health impacts on communities” and prioritize steps that will help mitigate the problems.
California officials recently sent water flowing from a pipe onto hundreds of acres of dry lake bed near the south shore, filling a complex of shallow ponds in an effort to create wetland habitat for fish and birds, and help control lung-damaging dust.
It’s not known how these new wetlands might affect emissions of hydrogen sulfide, and Freilich said she and her team plan additional studies focusing on wetlands and shallow-water areas.
Consuelo Márquez, a Coachella resident who has helped with the research, said she lived for several years as a child in North Shore, where she got nosebleeds and experienced the rotten egg odor, a “really strong fishy smell.”
“I would wake up with blood on my pillow,” she said. When she asked her father about it, she recalled him saying: “This happens because of the lake, because of the air.”
She said the study’s results validate the concerns many people have been raising for years.
Aydee Palomino, a co-author of the study and environmental justice project manager for the group Alianza Coachella Valley, said the study shows people are “breathing in pollutants that are under the radar of traditional monitoring systems.”
“This has the potential to have really far-reaching ramifications if it’s not addressed,” Palomino said.
Funding for the research came from the Burroughs Wellcome Fund, Google’s Environmental Justice Data Fund and NASA. But Freilich learned in March that the Trump administration had terminated the NASA grant under an order targeting diversity, equity and inclusion programs.
The researchers have an ongoing appeal of that decision, which Freilich said has been disruptive to ongoing work.
“The community is who’s going to suffer at the end of the day,” Palomino said. “And it is unfortunate because now it comes back to us to fill in the research gaps.”
Science
There were 13 full-service public health clinics in L.A. County. Now there are 6
Because of budget cuts, the Los Angeles County Department of Public Health has ended clinical services at seven of its public health clinic sites.
As of Feb. 27, the county is no longer providing services such as vaccinations, sexually transmitted infection testing and treatment, or tuberculosis diagnosis and specialty TB care at the affected locations, according to county officials and a department fact sheet.
The sites losing clinical services are Antelope Valley in Lancaster; the Center for Community Health (Leavy) in San Pedro, Curtis R. Tucker in Inglewood, Hollywood-Wilshire, Pomona, Dr. Ruth Temple in South Los Angeles, and Torrance. Services will continue to be provided by the six remaining public health clinics, and through nearby community clinics.
The changes are the result of about $50 million in funding losses, according to official county statements.
“That pushed us to make the very difficult decision to end clinical services at seven of our sites,” said Dr. Anish Mahajan, chief deputy director of the L.A. County Department of Public Health.
Mahajan said the department selected clinics with relatively lower patient volumes. Over the last month, he said, the department has sent letters to patients about the changes, and referred them to unaffected county clinics, nearby federally qualified health centers or other community providers. According to Mahajan, for tuberculosis patients, particularly those requiring directly observed therapy, public health nurses will continue visiting patients.
Public health clinics form part of the county’s healthcare safety net, serving low-income residents and those with limited access to care. Officials said that about half of the patients the county currently sees across its clinics are uninsured.
Mahajan noted that the clinics were established decades ago, before the Affordable Care Act expanded Medi-Cal coverage and increased the number of federally qualified health centers. He said that as more residents gained access to primary care, utilization at some county-run clinics declined.
“Now that we have a more sophisticated safety net, people often have another place to go for their full range of care,” he said.
Still, the closures have unsettled providers who work closely with local vulnerable populations.
“I hate to see any services that serve our at-risk and homeless community shut down,” said Mark Hood, chief executive of Union Rescue Mission in downtown Los Angeles. “There’s so much need out there, so it always is going to create hardship for the people that actually need the help the most.”
Union Rescue Mission does not receive government funding for its healthcare services, Hood said. The mission’s clinics are open not only to shelter guests, up to 1,000 people nightly, but also to people living on the streets who walk in seeking care.
Its dental clinic alone sees nearly 9,000 patients a year, Hood said.
“We haven’t seen it yet, but I expect in the coming days and weeks we’ll see more people coming through our doors looking for help,” he said. “They’re going to have to find help somewhere.” Hood said women experiencing homelessness are especially vulnerable when preventive care, including sexual and reproductive health services, becomes harder to access.
County officials said staffing impacts so far have been managed through reassignment rather than layoffs. Roughly 200 to 300 positions across the department have been eliminated amid funding cuts, officials said, though many were vacant. About 120 employees whose positions were affected have been reassigned; according to Mahajan, no one has been laid off.
The clinic closures come amid broader fiscal uncertainty. Mahajan said that due to the Trump administration’s “Big Beautiful Bill,” Los Angeles County could lose $2.4 billion over the next several years. That funding, he said, supports clinics, hospitals and community clinic partners now absorbing patients who previously went to the clinics that closed on Feb. 27.
In response, the L.A. County Board of Supervisors has backed a proposed half-cent sales tax measure that would generate hundreds of millions of dollars annually for healthcare and public health services. Voters are expected to consider the measure in June.
Science
Mobile clinic brings mammograms to women on Skid Row
Sharon Horton stepped through the door of a sky-blue mobile clinic and onto a Skid Row sidewalk. She wore a yellow knit beanie, gold hoop earrings and the relieved grin of a woman who has finally checked a mammogram off her to-do list.
It had been years since her last breast cancer screening procedure. This one, which took place in City of Hope’s Cancer Prevention and Screening mobile clinic, was faster and easier. The staff was kind. The machine that X-rayed her breast was more comfortable than the cold hard contraption she remembered.
Relatively speaking, of course — it was still a mammogram.
“It’s like, OK, let me go already!” Horton, 68, said with a laugh.
The clinic was parked on South San Pedro Street in front of Union Rescue Mission, the nonprofit shelter where Horton resides. Within a week, City of Hope, a cancer research hospital, would share the results with Horton and Dr. Mary Marfisee, the mission’s family medical services director. If the mammogram detected anything of concern, they’d map out a treatment plan from there.
Naureen Sayani, 47, a resident of Union Rescue Mission, left, discusses her medical history with Adriana Galindo, a medical assistant, before getting a mammogram on last week.
(Kayla Bartkowski / Los Angeles Times)
“It’s very important to take care of your health, and you need to get involved in everything that you can to make your life a better life,” said Horton, who is looking forward to a forthcoming move into Section 8 housing.
Horton was one of the first patients of a new women’s health initiative from UCLA’s Homeless Healthcare Collaborative at Union Rescue Mission. Staffed by third-year UCLA Medical School students and led by Marfisee, a UCLA assistant clinical professor of family medicine, the clinic treats mission residents as well as unhoused people living in the surrounding neighborhood.
The new cancer screening project arrives at a time of dire financial pressures on county public health services.
Citing rising costs and a $50-million reduction in federal, state and local grant and contract income, the Los Angeles County Department of Public Health on Feb. 27 ended services at seven of 13 public clinics that provide vaccines, tests and treatment for sexually transmitted diseases and other services to housed and unhoused county residents.
Although Union Rescue Mission’s own funding comes mainly from private sources and is less imperiled by public cuts, the 135-year-old shelter expects the need for its services to rise, Chief Executive Mark Hood said.
Even as unsheltered homelessness declined for the last two years across Los Angeles County, the unsheltered population on Skid Row — long seen as the epicenter of the region’s homelessness crisis — grew 9% in 2024, the most recent year for which census data are available.
For many local women navigating daily concerns over housing, food and personal safety, “their own health is not a priority,” Marfisee said.
Those whose problems have become too serious to ignore face daunting obstacles to care. Marfisee recalled one patient who came to her with a lump in her breast and no identification.
In order to get a mammogram, Marfisee explained, the woman first needed to obtain a birth certificate, and then a state-issued identification card. Then she needed to enroll in Medi-Cal. After that, clinic staff helped her find a primary care physician who could order the imaging test.
Given the barriers to preventative care, homeless women die from breast cancer at nearly twice the rate of securely housed women, a 2019 study found. Marfisee’s own survey of the mission’s female residents found that nearly 90% were not up to date on recommended cancer screenings like mammograms and pap smears, which detect early cervical cancer.
To address this gap, Marfisee — a dogged patient advocate — reached out to City of Hope. The Duarte-based research and treatment center unveiled in March 2024 its first mobile cancer screening clinic, a moving van-sized clinic on wheels that it deploys to food banks and health centers, as well as to companies offering free mammograms as an employee benefit.
“In true Dr. Mary fashion, she saw the vision,” said Jessica Thies, the mobile screening program’s regional nursing director. After working through some logistical hurdles, the mission and City of Hope secured a date for the van’s first visit.
The next challenge was getting the word out to patients. Marfisee and her students walked through the surrounding neighborhood, went cot to cot in the women’s dorm and held two informational sessions in December and January to answer patients’ questions.
At the sessions, the team walked through the basics of who should get a mammogram (women age 40 or older, those with a family history of breast cancer) and the procedure itself. (“Like a tortilla maker?” one woman asked skeptically after hearing a description of the mammography unit.)
The medical students were able to dispel rumors some women had heard: The test doesn’t damage breast tissue, nor do the X-rays increase cancer risk. Others questioned a mammogram’s value: What good was it knowing they had cancer if they couldn’t get follow-up care?
On this latter point, Marfisee is determined not to let patients fall through the cracks.
Thirteen patients received mammograms at the van’s first visit on Wednesday. Within a week, City of Hope will contact patients with their results and send them to Marfisee and her team. She is already mentally mapping the next steps should any patient have a situation that requires a biopsy or further imaging: working with their case manager at the mission, calling in favors, wrangling with any insurance the patient might have.
“It’ll be a good fight,” Marfisee said, as residents in the adjacent cafeteria carried trays of sloppy joes and burgers to their lunch tables. “But we’ll just keep asking for help and get it done.”
Science
Can fire-resistant homes be sexy? ‘You be the judge,’ says this Palisades architect
At first glance, it looks like nothing more than a charming Spanish-revival, quintessentially Californian home — but this Pacific Palisades rebuild is constructed like a tank.
Every exterior wall of the steel-framed home is a foot-thick, fire-resistant barricade. The home is connected to a satellite fire monitoring service. Should a fire start in town, sturdy metal shutters descend to cover every window. An exterior sprinkler system can pump 40,000 gallons of water from giant tanks hidden behind the shrubs in the property’s yard. If the cameras and heat sensors around the house detect danger, the system can envelop the home in over 1,000 gallons of fire retardant and hundreds of gallons of fire-suppressing foam.
Palisades resident and architect Ardie Tavangarian is so confident in his design that he even asked the fire department if they could start a controlled fire on the property to test it all out. (They said no.)
Tavangarian built a career designing multimillion-dollar luxury homes in Los Angeles, but after the Palisades fire destroyed 13 of his works — including his family’s home — he found another calling: how to design a house that can handle what the Santa Monica Mountains throw at it. And how to do it quickly and affordably.
Water tanks form part of a backup water supply in a newly built fire-resistant home in Pacific Palisades.
“Nature is so powerful,” he said, sitting on a couch in the new house, which he built for his adult twin daughters. “We are guests living in that environment and expecting, ‘Oh, nature is going to be really kind to me.’ No, it’s not. It does what it’s supposed to do.”
Tavangarian watched the Jan. 1 Lachman fire from his property not far from here; a week later that fire rekindled, grew into the Palisades fire, and burned through his house. But the painful details of the fire — the missteps of the fire department, the empty reservoir — didn’t matter when it came to deciding how to rebuild, he said. The reality is, many fires have burned in these mountains. Many more will.
A sprinkler on the roof is part of a house-wide sprinkler system.
For the architect, who has spent much of his 45-year career designing for luxury, hardening a home against wildfire has brought a new kind of luxury to his homes: peace of mind.
It’s a sentiment that resonates with fire survivors: Tavangarian says he’s received considerable interest from other property owners in the Palisades looking to rebuild their houses.
The metal shutters and advanced outdoor sprinkler system are the flashiest parts of Tavangarian’s home hardening project, and the efficacy of these adaptations is still up for debate. Because the measures have not yet been widely adopted, there are few studies exploring how much or little they protect homes in real-world fires.
Architect Ardie Tavangarian inside the house he designed.
Anecdotal evidence has indicated the effectiveness of sprinklers can vary significantly based on the setup and the conditions during the fire. Extreme wind, for example, can make them less effective. Lab studies have generally found shutters can reduce the risk of windows shattering.
These measures aren’t cheap, either. Sprinkler systems can cost north of $100,000, for example. However, Tavangarian said when all was said and done, the home he built for his daughters cost around $700 per square foot — less than what Palisades residents said they expected to pay, but more than what Altadena residents expected for their rebuilds.
Tavangarian also hopes to see insurers increasingly consider the home-hardening measures property owners take when writing policies, which he said could potentially offset the extra cost in a decade or less. As he explored getting insurance for the new home, one insurer quoted him $80,000 a year. After he convinced the company to visit the property, it lowered the quote to just $13,000, he said.
The house includes metal heat shields that can drop down if a fire approaches.
The home also has essentially all of the other less flashy — but much cheaper and well-proven — home hardening measures recommended by fire professionals: The underside of the roof’s overhang is closed off — a common place embers enter a home. The roof, where burning embers can accumulate, is made of fire-resistant material. The windows, vulnerable to shattering in extreme heat, are made of a toughened glass. There is virtually no vegetation within the first five feet of the home.
When asked if he felt he had compromised on design, comfort or aesthetics for the extra protection — one of the many concerns Californians have with the state’s draft “Zone Zero” requirements that may significantly limit vegetation within five feet of a home — Tavangarian simply said, “You be the judge.”
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