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Wildfire smoke increases dementia risk more than other forms of air pollution, landmark study finds

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Wildfire smoke increases dementia risk more than other forms of air pollution, landmark study finds

Exposure to wildfire smoke increases the odds of being diagnosed with dementia even more than exposure to other forms of air pollution, according to a landmark study of more than 1.2 million Californians. The study — released Monday at the Alzheimer’s Assn. International Conference in Philadelphia — is the largest and most comprehensive review of the impact of wildfire smoke on brain health to date, according to its authors.

“I was expecting for us to see an association between wildfire smoke exposure and dementia,” said study author Dr. Holly Elser, an epidemiologist and resident physician in neurology at the University of Pennsylvania. “But the fact we see so much stronger of an association for wildfire as compared to non-wildfire smoke exposure was kind of surprising.”

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The findings have big health implications, particularly in Western states, where air pollution produced by wildfires now accounts for up to half of all fine-particle pollution — a figure that’s been trending upward as wildfires grow larger and more intense due to climate change and legacies of fire suppression and industrial logging that have altered the composition of many Western forests.

The researchers looked at a type of particulate-matter pollution called PM2.5. These particles are 30 times smaller than the width of a human hair — tiny enough to penetrate deeply into the lungs and cross over into the bloodstream, where they can cause inflammation. Exposure has been shown to raise the risk of dementia and a host of other conditions, including heart disease, asthma and low birth weight.

“We increasingly see that PM2.5 is tied to virtually every health outcome we look at,” said study author Joan Casey, associate professor of public health at the University of Washington.

Elser, Casey and fellow researchers analyzed the health records of more than 1.2 million Kaiser Permanente Southern California members 60 or older between 2009 and 2019. None had been diagnosed with dementia at the beginning of the study.

They estimated each person’s exposure to PM2.5 based on their census tract of residence and then separated that into wildfire and non-wildfire pollution using air quality monitoring data, satellite imagery and machine learning techniques.

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They then looked at how many participants were eventually diagnosed with dementia. Unlike past studies, the researchers were able to determine this using patients’ full electronic health records, rather than relying on hospitalizations as a proxy for such diagnoses.

Looking at participants’ average wildfire PM2.5 exposure over three years, the researchers found a 23% increase in the odds of a dementia diagnosis for each increase of 1 microgram of particulate matter per cubic meter of air. When it came to non-wildfire PM2.5 exposure, they documented a 3% increased risk of dementia diagnoses for each increase of 3 micrograms of particulate matter per cubic meter of air.

“That’s what it comes down to, is what’s so different about wildfire smoke?” Casey said.

More research is needed to learn exactly what that is. Possibilities include the fact that wildfire particles are produced at higher temperatures, contain a greater concentration of toxic chemicals and are, on average, smaller than PM2.5 from other sources.

These ultrafine particles can translocate from people’s noses into their brains via the olfactory bulb, Casey said.

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“Normally the brain is protected by the blood-brain barrier, but here there’s actually a direct route for ultrafine particles to get into the brain and possibly cause some of the problems that we’re seeing in folks living with dementia,” she said.

The way in which people are exposed to wildfire smoke also differs from other types of fine-particle pollution, the researchers said. Background or ambient fine-particle pollution levels are usually relatively constant in a given place over time. But wildfire particulate matter tends to fluctuate wildly, resulting in more exposure over shorter periods of time, which may overwhelm the body’s defenses.

Of some 5,500 abstracts submitted to the Alzheimer’s Assn. International Conference, this one stood out due to its novelty, importance and impact, said Dr. Claire Sexton, senior director of scientific programs and outreach for the Alzheimer’s Assn.

“There have been other studies looking at different types of pollution, but this was unique in terms of the extent and the way in which it was able to do these analyses,” she said.

The researchers found the effects to be stronger on Asian, Black and Latino people, as well as those living in high-poverty areas. The most heavily impacted group was one that researchers classified as “other” because it didn’t contain enough people to differentiate further, Casey said. That group included Indigenous people, Pacific Islanders and people whose race was unknown.

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“So these disparities are playing out again, as we unfortunately often see with environmental exposures,” she said. “But the level at which we observed it here was fairly striking.”

Casey believes those disparities are due to differential exposure based on where populations are located, noting that her previous research has shown that Indigenous people in California have by far the highest levels of wildfire particulate exposure. Other factors could include poorer housing quality, lack of access to air filtration devices, jobs that prevent people from staying indoors during wildfire events and disparate responses to the same amount of pollution due to preexisting hypertension or diabetes, she said.

“All those things are driven by social determinants of health,” she said. “The fact that we need to allocate additional resources to these people and places to protect health and to try to reduce health disparities going forward is really important.”

The researchers did not differentiate between dementia subtypes like Alzheimer’s, the most common form, because they relied on diagnostic codes rather than using brain imaging or postmortem studies. That’s important to know — and a key area for future study — because in order to best protect people, clinicians need to have an understanding of what’s underpinning the relationship between wildfire smoke and different dementia subtypes, Elser said.

Still, the study is notable for its massive sample size and careful approach, taking into account sociodemographics like comorbidities and census tract poverty, said Rachel Whitmer, the director of the UC Davis Alzheimer’s Disease Research Center who was not involved in the research.

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The prevalence of dementia is on the rise as the baby boomer generation ages, but environmental factors may also be contributing to the increase, she said.

Research like this lays the groundwork for future studies, she said.

“With the increase in wildfires, this is a really important question and I think they did a really rigorous job in exploring it,” she said.

Levels of PM2.5 had been declining since the Clean Air Act took effect in 1970. But wildfires have reversed those trends in California, undercutting efforts to reduce emissions. In recent years, wildfire smoke has also affected the Midwest and East Coast. In 2023, smoke from Canadian wildfires blanketed the Atlantic seaboard, triggering air quality alerts and forcing the cancellation of outdoor events.

“It’s a big problem in places where wildfires are endemic,” Elser said. “And I worry that as we continue to experience increasingly frequent wildfire events, this could affect more people over a larger geographical distribution, more of the time.”

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Video: NASA Announces Artemis III Crew

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Video: NASA Announces Artemis III Crew

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NASA Announces Artemis III Crew

NASA announced the crew of Artemis III mission, which will fly to low-Earth orbit to test rendezvous and docking maneuvers with one or two lunar landers.

“I am excited to welcome you as the next crew in the Artemis journey to successfully return to the moon — this time to stay.” “I’m honored by the role that I’ve been given. I’m also very humbled by the task in front of us. But first and foremost, I’m grateful.” “So with that, the Artemis II crew, comrade, hands you the baton. You got the controls.” “As you know, we had a significant anomaly at our Launch Complex 36A on May 28. We’ve redoubled our efforts and are moving forward.”

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NASA announced the crew of Artemis III mission, which will fly to low-Earth orbit to test rendezvous and docking maneuvers with one or two lunar landers.

By Alisa Shodiyev Kaff

June 9, 2026

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Santa Monica Mountains’ last steelhead trout survived the Palisades fire — and even had babies

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Santa Monica Mountains’ last steelhead trout survived the Palisades fire — and even had babies

Scientists feared the Santa Monica Mountains’ last remaining steelhead trout were dead, smothered by debris flows unleashed by the Palisades fire.

But the endangered fish surprised them: A team of biologists recently spotted 30 of the rare trout — and 21 babies — in Topanga Creek.

“There was a lot of happy dancing in the creek,” said Rosi Dagit, principal conservation biologist for the Resource Conservation District of the Santa Monica Mountains, which works with public and private landowners to conserve natural resources.

That’s because the steelhead here are endangered, at both the state and federal levels. Once, they swam in most streams of the Santa Monicas, but their numbers plummeted amid overfishing and coastal development. Increasingly frequent wildfire has further stressed their habitat. Topanga Creek, a biodiversity hot spot, is home to their last known population in the mountains that stretch from the Hollywood Hills to Point Mugu in Ventura County.

The trout that were spotted, including this one, are part of a distinct Southern California population that’s listed as endangered at the state and federal levels.

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(RCDSMM Stream Team)

The California Department of Fish and Wildlife spearheaded a complex mission to rescue trout threatened by the Palisades fire that sparked in January 2025.

Time was of the essence. The fire hadn’t yet been fully contained. But rain was on the way, which would sweep massive amounts of sediment from the denuded hillsides into the water. Fish are often killed this way.

Crews stunned the fish with electricity, scooped them up in buckets, trucked them to a hatchery and ultimately moved them to Arroyo Hondo Creek in Santa Barbara County.

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Within days, Topanga Creek was choked with mud. Some assumed the fish left behind were goners.

But in March, the conservation district’s team found four. The following month, when water conditions were clearer, they saw more.

“These fish continue to amaze me,” said Kyle Evans, environmental program manager for the state Department of Fish and Wildlife, who had seen the damage to the creek. “I had seen populations get wiped out in similar situations. So when I heard, I was thrilled.”

Evans surmises the fish that survived were in an area of the creek where less charred material and sediment were swept in.

“These fish likely hunkered down, were hiding under some rocks or places to try to get away from the main concentration of flow,” he said. “And luckily they weren’t buried.”

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The ones that were spotted were fairly small, around 6 to 14 inches. Rainbow trout and steelhead trout are the same species, but with different lifestyles. If the fish remain in freshwater, they’ll be considered rainbows. However, they can migrate to the ocean and become steelhead, where they typically grow larger before returning to their natal waters to spawn.

Topanga Creek hasn’t fully recovered from the damage it sustained, but scientists say it’s looking better. Surveys last year were “so depressing,” Dagit said, with very few animals, and stretches that were essentially transformed into flat roads from all the sediment buildup. Some of the riparian canopy burned right down to the creek.

Then came 32 inches of rain over the last nine months, scouring out and moving sediment, creating deeper pools. Dagit said they recently found newt egg masses for the first time in years, as well as a few adult newts and many frogs. Plants that provide cover are starting to recover.

She provided photos comparing certain pools last year and this year, some dramatically transformed. In September 2025, the Shrine Pool could have been an overgrown hiking trail. This April, it was filled with shallow water.

Shrine Pool, Sept. 2025, left, and the same location, April 2026, right.

The Shrine Pool in September 2025, left, and the same location in April 2026, right, with RCDSMM’s Isaac Yelchin donning a wetsuit.

(RCDSMM Stream Team)

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Topanga Creek is home to another endangered fish, the small but hardy northern tidewater goby, often described as cute. Not long before the trout operation, Dagit led a rescue of hundreds of these fish too. Many were repatriated to the lagoon at the mouth of the creek in a moving ceremony last June.

There’s still the matter of what to do with the trout that were moved to Santa Barbara County last year. Evans would like to bring them home to the Santa Monicas at some point, but isn’t sure if it will happen. On one hand, they could bolster the small, genetically isolated surviving population. On the other, they might inadvertently bring in a disease or bacteria. There is some time to decide. Evans estimates the creek still needs to recover for two to three more years.

For now, the fish are functioning fine in their adopted creek. Experts worried the trauma wrought by the move would disrupt their spawning process, but they had babies that spring. This year, they spawned again.

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Pacifica pier cracks, another coastal casualty as seas continue to rise

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Pacifica pier cracks, another coastal casualty as seas continue to rise

The Pacifica Municipal Pier was shut down and taped off Thursday after city workers noticed cracks running through the landmark structure and concrete chunks falling into the ocean.

It’s just one of many coastal California structures that have recently crumbled under pressure from a rising and relentless ocean.

Officials from the small, beach city south of San Francisco said the pier was closed due to “cracking, separation, and displacement of the concrete walkway and structural elements.”

It will stay closed while structural engineers asses its safety.

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Photos taken by city employees show a wide crack that runs from top to bottom and across the structure as well. Other photos show a large horizontal crack under the foundation of a small restaurant on the pier, the Chit Chat Cafe.

The cafe was also shut down.

This is not the first time the 53-year-old pier has shown signs of stress. In 2021, part of it was shut down after handrails along the edge collapsed. And in 2023, after a series of storms pummeled the Central California coast, damaging parts of the pier, the structure was partially closed for more than year.

Those same storms caused extensive damage in Aptos and Capitola, 70 miles south, where piers and waterfront infrastructure were swept away or damaged.

In 2024, a 150- to 180- foot section of the Santa Cruz wharf was ripped off by powerful waves.

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At least 10 of the state’s dozens of coastal public piers were closed for part or all of 2024 due to structural damage sustained in winter storms since 2022. At least five others have longer-term upgrades planned to address structural issues.

“These things are costly to maintain,” said Zach Plopper, senior environmental director at Surfrider. “They are a part of our California coastal culture in many ways, but we’re going to need to reckon with, one, the state that they’re in, and two, the continuous and worsening threats they’re going to experience,”

He said most of the piers were constructed in the early 1900s, and they weren’t built to withstand decades of rough seas, storms and rising sea level.

“With this incoming El Niño, which is forecasted to be significant, and this marine heat wave we’re in the midst of, we’re kind of in uncharted waters as far as what this winter could bring in terms of storms and swells to the California coast, and we’re likely going to see a lot more damage,” he said. “Not just piers, but roads and other coastal infrastructure up and down the state.”

There was no storm in Pacifica earlier this week, so no single event could be blamed for the destruction.

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However, a 2025 report from an outside engineering firm, GHD, found that several sections of the pier were in “poor” or “serious” condition, and they recommended closure before anticipated storms or events that could “subject the piles to high winds, swells and large waves.”

The firm found several areas of the pier where concrete was missing and rebar was exposed and corroding.

“The pier has continued to experience high winds and large waves in a harsh marine environment,” the engineers wrote in the report, noting that continuous exposure to seawater or marine spray was “detrimental” to the structure.

A 2023 city report estimated it would cost $19 million to repair.

That same year, a state law was enacted to require local governments along the California coast to plan for sea level rise in the coming decades.

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Sea level has risen some 8 inches, on average, along the coast in the past 150 years, Plopper said, and researchers anticipate another foot in the next 25 years.

“We’re going to see profound shifts on our coastline, none that we have ever experienced before, and building static structures on the coast just doesn’t work all that well,” he said. “We’re going to have to make some really hard decisions.”

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