Air
Dust to Dust
How the Salton Sea’s toxic dust is poisoning the community.
By Iqbal Pittalwala
For the first time since 2011, California is no longer in a drought. A different story, though, is unfolding at the Salton Sea, the body of blue water marking the heart of inland Southern California that many people have only looked down on from airplanes.
The region has a melancholy air — literally and figuratively. Many experts point to the dusty, foul-smelling air as the root cause of health problems faced by many local residents.
“Asthma is at high levels in children who live near the Salton Sea,” said David Lo, director of the UCR School of Medicine’s BREATHE Center which stands for Bridging Regional Ecology, Aerosolized Toxins, & Health Effects. “Imperial County has nearly twice as many children with asthma as does the state; Riverside County fares only slightly better.”
The center, which brings together researchers on campus to study air quality and health, has been paying close attention to the Salton Sea. Its scientists apply computational models to study how the dust emanating from the exposed lakebed moves around the region. They also work with local communities, such as migrant farmworkers, to document and improve their health care access.
Despite the high number of children with asthma who live near the Salton Sea, “not much has been done to understand why this disease is so common here,” Lo added. “We see an inflammatory response to Salton Sea air that is strikingly different from the classic allergic inflammatory response.”
Work by BREATHE scientists provides the basis for exploring the mechanisms that explain why Salton Sea dust might predispose local residents to asthma and other airway-related illnesses. Preliminary data from mouse studies indicates exposure to the dust over just seven days elicits a dramatic neutrophil inflammatory response; neutrophils are immune cells that act as first responders in an inflammatory process. Neutrophil-dominant asthma is a subtype of asthma often seen in patients with occupational dust exposures. It does not respond to drugs typically used to treat allergic asthma.
“Through its work on the Salton Sea, UCR is informing the world about the potential impacts of climate change, and what effects such drying bodies of water can have on air quality and lung health,” said Tara Nordgren, an assistant professor of biomedical sciences who is collaborating with Lo and other BREATHE researchers, including junior specialist Abigail Burr. “Our Salton Sea work can absolutely be extrapolated to other areas of the world facing similar crises.”
BREATHE scientist Emma Aronson, an assistant professor of microbiology and plant pathology, is attempting to understand the microbiome — the community of microorganisms — of the Salton Sea dust. Aronson recalled the first time she saw the sea at ground level less than three years ago.
“I was struck by its quiet, stark beauty,” she said. “From far away, it appears as a huge inviting blue body, twinkling in the sunlight. I understood immediately how it became a resort destination. But as I got closer, I saw how out of balance the ecosystem was.”
Today, the vast majority of water entering the sea is highly contaminated agricultural runoff. The sea also receives seasonal runoff originating in Mexico. The boundary of the sea, as a result, is quickly shrinking, which exposes lakebed filled with unknown contaminants and unknown microbial communities that can produce high levels of toxins.
“The sea today is an unchecked, slow-moving environmental disaster,” Aronson said.
Connecting the Dots
Evaporation of the Salton Sea’s water has also generated a rapid spike in salinity, which, in turn, has created an unstable ecology. Hundreds of birds and fish now die periodically at the sea. Its beaches, tinged pink by crushed barnacles, are littered with their bones.
“If the ecology is shifting, we need to survey what microbes still linger here,” Lo said. “Are they stressed to the point where they are producing toxic chemicals that are part of the inflammatory response we see in our mouse studies? Can we expect to see something similar in the lungs of children living in that area? BREATHE is trying to tie it all together. If we identify a cause for the health issues, it could lead to policy changes and better treatment options for patients.”
Will Porter, an assistant professor of atmospheric dynamics and modeling, is helping to connect the dots through physics-based models he uses to understand wind-speed fluctuations at the sea. These models also help him figure out where the dust ends up and which populations are affected by it. He breaks up the Salton Sea region into grids and uses his models to estimate the likelihood of emissions occurring around specific shoreline areas.
“The models will lift the dust, and mobilize it based on wind speeds and directions,” he explained. “We can play with different times of year and evaluate the effectiveness of the simulations by comparing them to measurements made at stations. If the simulations compare well with observations, we can quantify how much dust came from a particular region.”
Assisting Porter with ground-based measurements is Roya Bahreini, an associate professor of environmental sciences. Bahreini and Alexander Frie, a graduate student, used samplers from Aronson’s laboratory that were adapted by Jon Botthoff of UCR’s Center for Conservation Biology to trap dust around the Salton Sea.
The samplers, which resemble bread pans, were left near the sea by BREATHE researchers for a month at a time. Laboratory analysis of the collected dust disclosed that it contained excessive salts — sodium, calcium, chloride, magnesium, and sulfates. It also contained traces of selenium, aluminum, and iron among other elements. The playa — the dry, exposed lakebeds that are thickly crusted with salts — is the dominant dust source for downwind areas, Bahreini said.
“Dust constituents that show similar co-variability are likely to have the same origin,” said Bahreini, whose laboratory studies aerosol sources and atmospheric processes that generate aerosols — minute particles suspended in the atmosphere. She first visited the Salton Sea in 2015 and was struck by a purple hue that saturated the sky.
She wondered if the aerosols were responsible and was surprised to discover that no one had examined aerosol composition at the Salton Sea.
When she launched her investigation, Bahreini’s first goal was to characterize particulate matter in the air, to see how much of PM10 — particulate matter at least 10 microns in size — comes from the playa and how much comes from the surrounding desert.
“We want to fundamentally understand the processes in the playa,” she said. “After rain, we get crusting over the playa due to salts being brought up from sediments below and dry air evaporating the water. But how much rain is necessary to enable these events? What wind speeds are needed to resuspend the crusted salts? We are still exploring these questions.”
The dynamic crust that cakes the silvery gray playas can look deceptively hard. Your foot, however, would sink a little with each step, leaving deep footprints. When wind sweeps over the playas, it scoops up the salts and transports them over long distances. While these salts are not unhealthy for the body, inhaling them can severely irritate the respiratory system.
Anthropologist Ann Cheney, an assistant professor in the School of Medicine’s Center for Healthy Communities, is familiar with the respiratory problems that migrant farmworkers in the fields around the sea experience on a near-daily basis. She is especially concerned about their poor access to health care services.
“This community’s health has been largely ignored,” she said. “Farmworkers here make up 60%-70% of the population and help make up the backbone of the American food chain. Understandably, they are concerned about the health of their families, especially during windstorms when many children suffer nosebleeds. But this is a community that lacks resources and a political voice. Many members are undocumented, poor, and have limited formal education. Their trailers are vulnerable to dust and winds. Health is not the main focus here — survival is.”
Cheney works closely with Maria Pozar, a community organizer at the sea, who is frustrated that the poor air quality is forcing many seniors out of the region.
“Here, children with persistent coughs get treated for a common cold,” she said. “Residents without health insurance self-medicate or use home remedies. The worst part is that most of them don’t even know that the air they’re breathing is causing these problems.”
Unless swift action is taken, the Salton Sea will impact far more people in the coming years, warned Darrel Jenerette, director of UCR’s Center for Conservation Biology, who has studied desert ecosystems for more than 20 years.
“The time to act on this catastrophe has long past,” said Jenerette, whose laboratory is studying how air pollution affects soil, and how soil, in turn, affects air quality. “The Salton Sea urgently needs a lot more research. Until I first visited the sea in 2007, I had little understanding of the tragedy unfurling there. I suspect this is true for most people who have never visited.”
Lo, who testified last year on Salton Sea air quality and health before the State Assembly Water Parks and Wildlife Committee, is hopeful California will fund more research on the sea.
“People seem more concerned about the impact of the dwindling sea on migratory birds than on the health of half a million people living around it,” he said. “That’s distressing.”
Airing it Out
By Holly Ober
When BREATHE wanted to study the effects that a lifetime spent breathing air around the Salton Sea might have on health, Professor David Cocker had an unusual request: to simulate the drying lake’s atmosphere.
Cocker studies ozone formation and particles formed through chemical reactions in the atmosphere, called secondary aerosols. He generates and measures experimental atmospheres in a large indoor environmental chamber research laboratory at the Center for Environmental Research and Technology.
“A lot of our research is simulating reactive conditions and trying to understand and identify which chemicals are driving the ozone and secondary aerosol formation,” he said. “We want to learn what the mechanisms are so models can accurately predict air quality.”
Most studies of air quality health effects do not attempt to recreate the air in question. They rely instead on experimental methods that don’t replicate real-world exposure.
“The beauty of this is it’s a highly collaborative program between engineering and the School of Medicine,” Cocker said.
Cocker built an enclosed chamber about 1 meter long on each side and a half meter high. The box is roomy enough to house mice comfortably. He pumps air into the enclosure with particle composition that closely mimics that of the Salton Sea, including water, soil, and biological particles.
“We’re really just working on recreating the typical atmosphere but under controlled laboratory conditions,” Cocker explained.
