Ash and Debris: Environmental Impacts of Los Angeles Fires

Santa Monica resident Susan Suntree stood on the beach in Santa Monica. Five miles from the burn zone, the environmental impact could still be seen and felt. The once picturesque beach was covered in a thick layer of ash and debris, turning the golden sand black.

“I wanted to take my dog but they’re saying the beach is toxic,” said Suntree.

When the devastating Eaton and Palisades fires were finally contained, the focus shifted from fighting the fires to recovery and clean-up. But what is it that needs to be done? What pollutants does a fire release? What hazardous material remains after a fire burns down a neighborhood of family homes?

“Within wildfire smoke there’s going to be various gases,” said Sean Boland, A PhD candidate at Colorado State University’s Montrose Lab. “Carbon Dioxide, Nitrogen Oxide, things of that nature. There can be other pollutants if you think about not just the trees and bushes burning, but if you’re having infrastructure burning too.”

The Montrose Lab studies the effects of wildfire smoke on various systems of the body; Boland focuses on the smoke’s effect on the cardiovascular system. Boland explained that with wildfire smoke, the main concern is particulate matter, the small particles of burnt material that carry within the smoke.

Boland says that when this particulate matter is absorbed into the bloodstream, it can cause health issues in many different body systems. The Montrose Lab has extensively studied the effects that this matter has on the cardiopulmonary system, as it can cause issues with circulation, blood pressure and irregular heartbeats. Boland also added that studies in the Montrose Lab have shown that wildfire smoke can also cause issues within brain cells and spermatogenesis.

“There’s been research that it can get to the brain and there’s some connection between air pollution and dementia and things like that,” said Boland. “But there’s a lot of questions of how that happens.”

A fire of this magnitude affects not just people, but the environment around them as well. The same pollutants that are let off in the smoke also fall onto the ground and seep into the waterways. Fire retardant chemicals used to fight the flames can also cause environmental issues as they get washed away.

“I have to take all the soil out of my garden because the ash has made it toxic,” said Suntree.

While the fires burned in Pacific Palisades and Altadena, winds blew smoke and debris all over the surrounding areas. In Santa Monica, five miles from the Palisades burn zone, burnt ash and debris lined the beaches. Santa Monica Beach, one of the big draws for tourism in the city, was covered with a blanket of burnt wood and building materials. This has harmed some local businesses that rely on tourist business. Some vendors only have permits to sell on the beach itself, and with no one on the beach, they have no one to sell to.

With all the pollution that has made its way into the waters near the burn zones, researchers are working to study what kind of effects it will have.

Heal the Bay has been researching pollution effects on marine life since the fires burned in January. The organization says that heavy metal levels in the ocean have risen since the fire, causing serious risk for marine mammals and other species high on the food chain. This affects humans indirectly, as heavy metals can accumulate within sea life that may then be consumed by humans.

“This fire is pretty unique and it’s something we haven’t seen anything quite like this before,” said Naomi Meurice, a water quality data specialist at Heal the Bay, a non-profit that advocates for cleaner water in the Los Angeles area.  

“In short, when animals get sick, humans can get sick, particularly from consuming seafood that has a bioaccumulation of metals in their systems,” said Heal the Bay in their Ash to Action newsletter.  

Heal the Bay says that water toxicity levels are low enough to be safe for humans, but hazardous debris remains in the water and on the beaches. This debris may contain sharp objects like nails and glass, and may be toxic as well. Beachgoers are recommended to wear closed-toe shoes and not touch any debris. 

Debris removal has begun on houses along the Pacific Coast Highway, which Heal the Bay says will mitigate the risk of more pollution leaking into the ocean. The organization recommends that beachgoers avoid debris removal and surrounding areas, as the process may stir up pollutants in the area, creating health risks.

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This story is part of a semester-long investigative reporting project into the 2025 California wildfires. It was created by an advanced reporting class in the Journalism, Advertising, and Media Studies program at UW-Milwaukee. Other stories from the project are available here.

This work was made possible through the support of MPC Endowment Ltd., the philanthropic affiliate of the Milwaukee Press Club.