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The inferno flames burning in Southern California are raising concerns about the potential airborne hazards they may be leaving behind.
Even after the fires are out, experts warn, pollutants from the structures they destroyed — some of them potentially containing toxic materials — could remain in the air and pose uncertain health hazards. .
Although it is not concluded how many buildings have burned, estimates indicate that at least 15,000 structures succumbed to the flames of the initial Palisades and Eaton fires. And some “will have experienced significant damage from smoke and toxic ash deposits,” noted Daniel Swain, a climate scientist at the University of California, Los Angeles. in a webinar earlier this week.
“This is a growing concern in the wake of this highly urban fire that burned not only vegetation, but a lot of structures that contain things like lead paint, asbestos, various heavy metals contained in the batteries that burned to vehicles and home system backups and solar panels,” he said.
Describing those losses as “a staggering toll,” Swain warned of the collateral damage residents could suffer from exposure to smoke and toxic ash.
“The health damage, illness and sometimes death that can result from large-scale disasters and wildfires are not limited to people who do not leave the fire zone,” he added.
Facing a likely rainy weekend, the Fire of Palisadesthat has devastated the Pacific Palisades neighborhood, was 23,448 acres and 77 percent contained. Eaton’s firenorth of Pasadena, it was 14,021 acres with 95 percent containment. But the new Hughes Firethat began Wednesday near Castaic Lake, had grown to 10,396 acres and was only 56 percent contained.
Smoke from forest fires contains a mixture of pollutants, although the most well-studied ingredient is fine particulate matter (PM 2.5). When inhaled, these tiny particles can invade the lungs and enter the bloodstream, said Tarik Benmarhnia, a climate change epidemiologist at the Scripps Institution of Oceanography at the University of San Diego. in a recent explanation.
In addition to exacerbating existing conditions such as asthma, repeated exposure to PM 2.5 is also associated with future lung cancers, cardiovascular disease and dementia, Benmarhnia said. He and his colleagues have recently demonstrated how repeated exposures to PM 2.5 from wildfire smoke over several years can increase the risk of developing dementia and Alzheimer’s disease.
Shedding light on the extent of wildfire smoke, Scripps Oceanography researchers announced Tuesday that they identified ash and debris up to 100 miles offshore, raising concerns about potential impacts to fisheries and netting wider trophic.
“These fires not only consume vegetation, but also large amounts of urban infrastructure,” said project leader Julie Dinasquet. he said in a statement. “This introduces a new ‘urban ash’ component to the wildfire source, full of exceptionally toxic materials.”
Among the materials it flagged were lead, arsenic, asbestos, microplastics and polycyclic aromatic hydrocarbons, organic compounds found naturally in fossil fuels.
“These fires pose a significant potential threat to both humans and ecosystems by introducing a large amount of toxic material into the system,” Dinasquet added.
Public health risks full of uncertainty
Precisely, it is not known to what extent the public health threat of these wildfires will be, who will be affected by this threat and when.
Richard Castriotta, a pulmonologist at the Keck School of Medicine at the University of Southern California, noted the “huge difference” between urban wildfires like those burning in Los Angeles and those that only affect trees.
Acknowledging that the dangers associated with wildfire smoke are real, Castriotta told The Hill they pale in comparison to the potential pollutants released by a burning building.
He also described a wide variety of toxic substances involved in these exposures, including chlorine, lead, asbestos and nitrogen oxides, as well as mysterious materials, created as a high-intensity flame “turns plastics and man-made materials into substances unknown.”
“The danger is there for everyone, but it’s naturally worse for people who have lung disease, heart disease, diabetes and impaired immunity,” said Castriotta, who also noted that pregnant and breastfeeding people could be at risk. at risk
Children, on the other hand, are particularly vulnerable and should not participate in the cleaning of houses burned in the flames, he stressed.
The short-term effects of smoke exposure tend to occur in both the upper and lower respiratory tract, with the nose filtering out many of the larger particles and then the lungs acting as a “first responder” to some of the smaller particles , explained Castriotta.
“This is our first immune response, and so if there are a lot of toxic particles coming in, it can overwhelm the immune response system,” he said. “This would make the person, regardless of previous health status, relatively immunocompromised, unable to cope with additional burdens, like the firefighters themselves.”
In the coming days and weeks, this immune impairment could lead to an increased likelihood of contracting respiratory illnesses such as pneumonia, influenza, COVID-19 and bronchitis, Castriotta added. As for people who are already sick, he said exposure could worsen conditions such as asthma, chronic obstructive pulmonary disease, pulmonary fibrosis and heart disease.
Castriotta acknowledged, however, that he doesn’t know what the long-term effects of exposure to these fires will be and that he’s “not sure if anyone does.” Referring to the collapse of the Twin Towers on 9/11, he noted how long it took to determine the health impacts of first responders. And while he acknowledged the differences between these situations, he described similar uncertainties.
A potential problem in many of the homes that burned could be the presence of asbestos, which Castriotta described as “a durable, fire-retardant fiber that lasts forever.” If these fibers reach the lungs, the “first responder” white blood cells “don’t have the ability to digest and destroy them,” he explained.
“This is why there is a long latency period from asbestos exposure and adverse consequences that can be up to 30 years,” he said.
At the same time, Castriotta noted that the long-term impact depends on both the duration and extent of exposure, and that inhaling a single asbestos particle would not lead to disease.
Things could have been worse
Although air pollution levels in these dense urban conditions could be dire, the circumstances could have been even worse if the fires had occurred in summer instead of winter.
Alexei Khalizov, a professor of chemistry and environmental science at the New Jersey Institute of Technology, attributed this difference to the higher levels of ground-level ozone that are noticeable on summer days in Los Angeles.
Wildfires, he explained, produce high concentrations of chemicals that exhibit a range of volatilities, with low-volatile compounds that condense onto soot particles quickly as the smoke cools.
According to Khalizov, the more volatile chemicals are not able to condense as quickly and instead travel in the air alongside the soot and interact with other pollutants, such as ozone. Only then do they become less volatile and begin to condense on the soot, thus increasing the toxicity of these particles, he noted.
Among the volatile compounds that most alarmed Khalizov was polyvinyl chloride (PVC), a common ingredient in plastics. He was referring to the 2023 train derailment in East Palestine, Ohio, after which officials made the controversial decision to burn tanker trucks of vinyl chloride, a cancer-causing chemical used to make PVC, to prevent an explosion
“Polyvinyl chloride is not very different from the chemical used to make it,” he said.
In an urban wildfire scenario, Khalizov raised concerns about the combined effects of multiple pollutants, or what he described as “synergism between pollutants.”
“If you’re exposed to smoke and ozone together, they actually have a much worse effect,” he said.
Risks when returning home
As residents begin to return to their charred homes and clean up the debris, Castriotta recommended they do so only with N95 masks and goggles, while cautioning that air quality indices do not account for the toxic materials that he mentioned
“People will look at the air quality index and say, ‘Oh, it’s moderate, or it’s good, it’s regular LA air,'” Castriotta said. “But that doesn’t measure the specific toxins that are release from these particular fires.”
UCLA’s Swain also urged residents to wear particulate-filtering masks and use HEPA filters indoors, citing countywide health advisories for wind-borne ash that could be “falling from the sky.”
Taking such measures, he reiterated, could help minimize the future repercussions of such disasters, especially since smoke and ash can persist even after a fire is largely extinguished.
“The health damage, casualties and injuries in the days and weeks and months and even years that follow are indirect and harder to quantify,” Swain added. “These kinds of large-scale disasters have a far greater cost than we’ve really been able to easily quantify in the last few decades.”
