{"id":349882,"date":"2026-06-06T20:53:22","date_gmt":"2026-06-06T20:53:22","guid":{"rendered":"https:\/\/www.newsbeep.com\/us-ca\/349882\/"},"modified":"2026-06-06T20:53:22","modified_gmt":"2026-06-06T20:53:22","slug":"carcinogen-from-la-fire-cleanup-may-have-spread-up-to-9-miles-downwind-study-shows","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us-ca\/349882\/","title":{"rendered":"Carcinogen from LA fire cleanup may have spread up to 9 miles downwind, study shows"},"content":{"rendered":"

A potent carcinogen may have spread to communities as far as nine miles downwind of the Eaton and Palisades fire burn zones during debris clean-up, according to a new peer-reviewed study<\/a> in the journal Nature.<\/p>\n

A team of researchers has been studying<\/a> the air pollution effects of clearing the remains of more than 16,000 homes and businesses destroyed in the 2025 fires.<\/p>\n

Scientists with UCLA and UC Davis drove through Altadena and Pacific Palisades in an electric vehicle with mobile air monitors periodically over about seven months after the fires. They measured nanoparticles of hexavalent chromium, or chromium-6, within the cleanup areas. Paint, auto parts, electronics and fire retardant<\/a> are possible sources, but more study is needed to understand where the chromium came from, the researchers said. They also detected other airborne metals, including lead and arsenic.<\/p>\n

The researchers used computer modeling to understand how far those airborne particles may have spread beyond the immediate burn zones. About 3 million people live in the areas that could have been exposed, according to the scientists\u2019 models.<\/p>\n

Keep up with LAist.<\/p>\n

If you’re enjoying this article, you’ll love our daily newsletter, The LA Report. Each weekday, catch up on the 5 most pressing stories to start your morning in 3 minutes or less. <\/p>\n

The highest concentrations of nanoparticles \u2014 particles less than 1\/1,000th the width of a human hair \u2014 were measured in March 2025, about two months into the debris removal effort in both burn zones. But the toxicity declined as time passed.<\/p>\n

\u201c\u200aThe good news is that some of those toxic metals, they were converted back to less toxic forms over time,\u201d said Michael Kleeman, professor of civil and environmental engineering at UC Davis and lead author of the study. \u201cSo in the months after the wildfire, the threat from this sort of decayed away.\u201d<\/p>\n

In communities outside the burn zones, concentrations diluted further as the plume moved downwind, Kleeman said. By eight months after the fires, the researchers measured that heavy metal concentrations had fallen to background levels for the L.A. basin.<\/p>\n

The research highlights how \u201ceven after the fire is over, the danger isn’t gone,\u201d Kleeman said.<\/p>\n

An aerial view of properties cleared of fire debris in Altadena in July 2025.<\/p>\n

(<\/p>\n

Mario Tama<\/p>\n

\/<\/p>\n

Getty Images<\/p>\n

)<\/p>\n

Cleared lots in the Palisades Fire burn zone stretch into the distance.<\/p>\n

(<\/p>\n

Qian Weizhong <\/p>\n

\/<\/p>\n

VCG \/ Associated Press<\/p>\n

)<\/p>\n

How concerned should you be?\u00a0<\/p>\n

The researchers and outside experts emphasized to LAist that the study\u2019s findings do not prove widespread contamination of homes, businesses or the environment.<\/p>\n

\u201c\u200aI hope we can get a message of caution out there, but not panic,\u201d said Kleeman.<\/p>\n

Andrew Whelton, a Purdue University post-disaster environmental risk researcher who was not involved in the study, said the research is far from proving what, if any, harm to human health could occur, especially because no indoor testing was carried out.<\/p>\n

\u201cDrawing a line from street-level detections to indoor exposure, without confirming that the [chromium-6] outdoors entered homes at levels posing health risks, is a significant leap,\u201d he said.<\/p>\n

Whelton, who carried out soil testing<\/a> in the L.A. fire burn scars, said he worries the paper could needlessly sow fear because so many open questions remain. He has argued for<\/a> funding and establishing more comprehensive contaminant testing at the individual household level in the wake of such destructive fires \u2014 the most definitive way to know your personal risk.<\/p>\n

\u201cThe bottom line: detecting nanoparticles in outdoor air does not mean harm occurred to 3-plus million people living and working inside buildings,\u201d Whelton told LAist.<\/p>\n

The average levels of chromium-6 detected in the air during debris cleanup in March were well below limits set for workplaces by the Occupational Health and Safety Administration, but above the U.S. Environmental Protection Agency long-term screening levels for homes, according to the study.<\/p>\n

Still, those comparisons are imperfect because the particles measured were far smaller than what\u2019s used for current health standards \u2014 meaning they can more easily travel throughout the body, Kleeman said.<\/p>\n

\u201cWe don’t know for sure what the concerning level should be,\u201d he said.<\/p>\n

Workplace standards, for example, are set for healthy adults working eight-hour shifts, \u201crather than for sensitive populations such as young children, pregnant individuals, older adults, or people with chronic illness,\u201d said Jun Wu, an environmental health scientist and professor at UC Irvine\u2019s School of Public Health, who also was not involved with the study.<\/p>\n

More comprehensive study is needed to get at what true exposures may, or may not, have occurred, Kleeman and outside researchers emphasized.<\/p>\n

\u201cThis is a single, novel finding based on limited sampling, with the downwind reach estimated by modeling,\u201d Wu said, \u201cso broader monitoring is the natural next step.\u201d<\/p>\n

Where the nanoparticles may have spread<\/p>\n

The broadest potential plume was from the Palisades Fire, spreading as far as the southern San Fernando Valley to the north and Beverly Hills and West Hollywood to the east. Kleeman said computer modeling of prevailing winds show the plume being pushed toward central L.A.<\/p>\n

\u201cSanta Monica, Venice and moving toward central L.A. took the brunt of the plume,\u201d Kleeman said.<\/p>\n

Prevailing winds didn\u2019t spread the plume quite as far in communities near the Eaton Fire, with modeling showing northeast Pasadena being the primary community affected.<\/p>\n

\"A<\/p>\n

A map from the study showing the ZIP codes where a airborne chromium-6 may have spread during debris removal. <\/p>\n

(<\/p>\n

Courtesy UCLA \/ UC Davis<\/p>\n

)<\/p>\n

Many unknowns remain about the public health effects of catastrophic fires in urban areas \u2014 and how far those risks may drift beyond the burn zone.<\/p>\n

\u201cMore work is needed to understand how widespread and persistent these particles were, how exposure varied by location and cleanup activity, and what the health risks were for nearby residents,\u201d said Sina Hasheminassab, an air quality researcher at NASA\u2019s Jet Propulsion Laboratory who was not involved in the study.<\/p>\n

How to protect yourself during and after a major urban wildfire<\/p>\n

Debris cleanup workers and residents in or within nine miles downwind of the burn zones in the year after the L.A. fires should be mindful of any new health symptoms and report them to a doctor. You can also find resources, report symptoms or ask questions via the ongoing LA Fire Health Study<\/a>.<\/p>\n

Steps to take to reduce contaminant exposure during or in the wake of an urban wildfire:<\/p>\n

Your HVAC system should have MERV-13 or higher HEPA filters.Standalone air purifiers should have HEPA and carbon filters.If there\u2019s a risk of exposure to smoke or particles from active fire or debris cleanup, wear an N95, KN95 or equivalent mask outside. Keep windows and doors closed at home. Consider putting wet towels or more secure types of sealants along sills and doorframes to help prevent smoke or dust getting in.Wipe down dusty areas with wet cloth to prevent particles from becoming airborne.Don\u2019t bring potentially contaminated clothing or shoes indoors.\u00a0<\/p>\n

The surest way to understand your personal risk of exposure to toxins is to get your home\u2019s air and soil tested. Here are some resources to learn more about that and what to test for:<\/p>\n

Post Fire\u2019s expert Q&As<\/a> answer many common questions from fire survivors.The L.A. Fire Health Study also has these resources<\/a>.Purdue University has recorded webinars<\/a> for various aspects of fire recovery, as well as helpful information for soil testing here <\/a>and here<\/a>.\u00a0<\/p>\n

Additionally, the study raises questions about how to better protect people\u2019s health not only during, but also after destructive urban fires, said Wu.<\/p>\n

\u201cMuch of our attention goes to the smoke during the active fire, but this study points to the cleanup and recovery phase,\u201d she said. \u201cThis time window deserves just as much attention as the fire period itself.\u201d<\/p>\n

For example, some survivors whose homes survived never left during debris removal \u2014 some cited concerns<\/a> about not being able to afford another place to stay without upfront insurance payouts<\/a>, as well as worries about looting<\/a>. <\/p>\n

The study notes that workers in the burn zones faced the highest risk.<\/p>\n

\u201cBased on our field observations, many workers in the debris cleanup zone did not wear masks despite California requirements to provide approved air purifying respirators to workers,\u201d the researchers wrote.<\/p>\n

\"A<\/p>\n

Crews remove wildfire debris on hillside property in Pacific Palisades last year. Researchers note in a recent study that many workers they saw weren’t using respiratory protection. <\/p>\n

(<\/p>\n

Charles Delano<\/p>\n

\/<\/p>\n

U.S. Army Corps of Engineers<\/p>\n

)<\/p>\n

Survivors push for policy to protect public health after wildfires<\/p>\n

Nicole Maccalla\u2019s home in Altadena was damaged but ultimately survived the Eaton Fire. She and her two teenagers moved back in nearly six months after the fire, while debris removal was ongoing. Her daughter\u2019s school nearby was also reopened just a month after the fires.<\/p>\n

\u201c\u200aI know I was exposed. I know my kids were exposed,\u201d Maccalla told LAist. \u201cI’m not really sure what to do with that, to be honest.\u201d<\/p>\n

\u201cOur entire community is really now guinea pigs,\u201d she added. \u201cIt\u2019s deeply concerning.\u201d<\/p>\n

\"A<\/p>\n

Nicole Maccalla, with her kids, Seb and AJ. Their Altadena home survived the Eaton Fire but suffered serious smoke damage. <\/p>\n

(<\/p>\n

Courtesy Nicole Maccalla <\/p>\n

)<\/p>\n

Maccalla, a data scientist and member of Eaton Fire Residents United<\/a>, helped guide ongoing research by scientists like Kleeman to better understand the levels of contamination after the fires.<\/p>\n

She said this study is a warning.<\/p>\n

\u201c\u200aI think in the future, we need to move a little slower in fire recovery. The goal should not be speed. The goal should be health and safety,\u201d Maccalla said. \u201cWe rushed it, and I hope that we learn from this mistake.\u201d<\/p>\n

She and fellow survivors see some hope in a new bill they helped inform. AB 1642<\/a>, or the Wildfire Environmental Safety and Testing Act, is making its way through the California Legislature.<\/p>\n

The bill, written by Assemblymember John Harabedian, would establish the first statewide health standards for testing and cleaning up debris in and outside standing homes, schools, businesses and other structures after a wildfire.<\/p>\n

Maccalla urged fellow survivors worried about the results of this study to prioritize caring for their mental and physical wellbeing.<\/p>\n

\u201cThe stress of all of this is just going to be an added component that will be another contributor to us getting sick long term,\u201d she said. \u201cSo many of us are still in survival mode. It’s time, I think, to start taking care of ourselves a little bit.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"A potent carcinogen may have spread to communities as far as nine miles downwind of the Eaton and…\n","protected":false},"author":2,"featured_media":347935,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[27],"tags":[100536,132990,8321,3802,143179,48,52,51,47,50,49,8320],"class_list":["post-349882","post","type-post","status-publish","format-standard","has-post-thumbnail","category-los-angeles","tag-carcinogen","tag-chromium","tag-eaton","tag-fire","tag-heavy-metals","tag-la","tag-la-headlines","tag-la-news","tag-los-angeles","tag-los-angeles-headlines","tag-los-angeles-news","tag-palisades"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/349882","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/comments?post=349882"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/349882\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media\/347935"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media?parent=349882"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/categories?post=349882"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/tags?post=349882"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}