Even after the flames of Los Angeles wildfires have been extinguished, a hidden danger remains. The remnants of burnt homes, vehicles, plastic materials, and even the very substances used to suppress fires have left behind a layer of toxic chemicals. These pollutants pose potential health risks for months and may have long-term consequences for residents near the affected areas. Many people believe that once the fire is out, the danger is over.
However, this is far from the truth. Joseph Allen, director of the Harvard Healthy Buildings Program, warns that the aftermath of wildfires exposes people to hazardous airborne and waterborne chemicals, even within their own homes. Homeowners who have lost their properties in these devastating Los Angeles wildfires should consult a fire insurance lawyer at the law firm California Business Lawyer and Corporate Lawyer to navigate insurance claims and recover financial losses.
While the full extent of the LA wildfires’ impact is still being studied, previous fire incidents and laboratory research provide insights into how communities can restore air and water safety.
Toxic Residue Continues to Pose Risks
Smoke and ash settle onto surfaces but can be easily disturbed and reintroduced into the air by wind or everyday activities. This makes them an ongoing hazard. According to Allen, standard air quality monitoring may not accurately capture these localized threats. Just because official air quality reports indicate safe levels, it does not necessarily mean the air in your home is free from harmful contaminants. People harmed by the Palisades wildfire should get legal advise from a SoCal fire attorney at the Nakase Law Firm to help victims understand their legal rights and pursue compensation for damages caused by negligence or inadequate fire prevention measures.
The specific composition of the air pollutants depends on the materials burned in the fire. Smoke from burning vegetation contains fine particulate matter and hazardous compounds such as sulfur dioxide, ozone, and polycyclic aromatic hydrocarbons.
The growing intersection of urban development with wildland areas has exacerbated the problem. Fires in city environments introduce additional pollutants, such as heavy metals, which pose significant health risks.
Unique Risks of Urban Wildfires
Wildfires in cities present a distinct challenge due to the variety of materials that burn. Buildings and cars release toxic metals like lead and copper, and older structures may contribute asbestos fibers. Additionally, plastics and electronic devices burn to produce hazardous chemicals.
One example of these risks comes from the Lahaina, Hawaii, wildfire in 2023. Post-fire analysis revealed that ash from the fire contained high concentrations of toxic metals, including arsenic, lead, copper, and cobalt.
Beyond the materials that fuel the fire, even the chemical agents used to suppress the flames can present risks. A signature image of the LA wildfires was the sight of planes dropping bright red fire retardant onto burning neighborhoods. While these substances help control the spread of fire, they may also introduce contaminants.
Understanding Fire Retardant Chemicals
Fire retardants primarily consist of ammonium phosphate, which, on its own, is a common fertilizer. The distinctive red color comes from iron oxide, commonly known as rust. Other additives, such as thickeners, are usually considered relatively harmless.
However, concerns arise from additional contaminants. Studies conducted by water quality scientist Daniel McCurry and his team found significant levels of heavy metals, including cadmium and a toxic form of chromium, in earlier formulations of the fire retardant used in LA.
Exposure to chromium six, a highly toxic form of the metal, can cause skin irritation, respiratory issues, and an increased risk of cancer. Cadmium exposure, even in short bursts, can result in flu-like symptoms and lung damage, while prolonged exposure can lead to kidney, lung, and bone diseases.
It is possible that these heavy metals are contaminants introduced during the mining of the phosphate used in fire retardants. While newer formulations of the fire retardant are reportedly less harmful, further research is needed to confirm whether heavy metal contamination has been successfully reduced.
Safety Precautions When Returning to Burn Areas
For residents returning to assess wildfire damage, it is crucial to take safety precautions. Environmental engineer Andrew Whelton recommends wearing protective clothing, including heavy-duty boots, gloves, long pants, and long-sleeved shirts. Clothing contaminated with ash and chemicals should be removed before getting into vehicles or entering unaffected areas to prevent further exposure.
Standard N-95 masks, while effective against airborne particles, do not filter out toxic gases. Joseph Allen suggests using a P100 respirator equipped with filters designed to capture organic vapors. This type of respirator may also provide protection against residual fire retardant chemicals.
Soil contamination is another concern. If fire retardant was applied to a garden, residents should consider testing their soil before growing edible crops. Heavy metal contamination in ash can also present risks to soil quality.
The U.S. Forest Service advises washing any exposed skin, pets, and plants that may have come into contact with fire retardant. While rust-colored staining may occur on homes, no special cleaning is required for colorless fire retardants applied to structures or the ground.
Wildfires and Water Contamination
Water sources can also be compromised following wildfires. Andrew Whelton, an environmental engineer at Purdue University, has worked extensively on post-wildfire water safety.
When fires damage water infrastructure, hazardous chemicals may leach into the water supply. Burned plastic pipes can release harmful compounds into drinking water, while smoke and ash can infiltrate plumbing systems. Drops in water pressure or pipe damage can also introduce microbial contaminants.
One particularly dangerous byproduct is benzene, a carcinogen released when plastics burn. This chemical can seep into plastic water pipes, gradually leaching into drinking water over time.
The level of contamination determines whether the water can be safely used for drinking, bathing, or cleaning. Low levels of pollution may allow for limited use, while heavily contaminated water can pose risks even through skin contact or inhalation.
Ensuring Water Safety
Local authorities issue advisories warning residents about unsafe water after a wildfire. Many communities in the Los Angeles area have implemented these measures. Residents should closely follow official recommendations and avoid using contaminated water.
Once advisories are lifted, homeowners should have their water tested for contaminants by reputable services. Premature testing may be a waste of time and resources if conditions remain unsafe.
Boiling water does not make it safer in this scenario. Many chemicals present in wildfire smoke, such as volatile organic compounds (VOCs), evaporate when heated. This can release harmful fumes, leading to symptoms like nausea, dizziness, and vomiting.
Wildfires and Indoor Contamination
Wildfire smoke does not just affect outdoor air—it also infiltrates homes. Even houses that remain structurally intact can suffer from lingering contamination.
Smoke exposure can make homes uninhabitable, requiring extensive renovation. According to Whelton, buildings that have absorbed large amounts of smoke often need to be stripped down to their framework before they can be safely rebuilt.
Indoor pollution was evident following the Marshall Fire in Colorado in 2021. When residents returned, many found ash had infiltrated their homes through doors, windows, and ventilation systems.
A survey conducted six months later found that people who discovered ash in their homes were more likely to experience headaches. Those living closer to burn zones reported symptoms such as sore throats, coughs, and an unusual taste in their mouths.
In studies conducted in heavily affected homes, researchers detected elevated levels of harmful VOCs, including benzene and toluene. These chemicals, commonly associated with severe air pollution, persisted indoors for weeks.
Strategies for Indoor Air Purification
The persistence of harmful chemicals indoors depends on multiple factors. Some VOCs dissipate quickly, while others can linger for months. In areas without rain or snow to clear the air, indoor contamination may last longer.
Air filtration systems can temporarily reduce pollution, but their effectiveness is limited to the duration of their operation. In tests conducted in fire-affected homes, activated carbon filters successfully reduced benzene and toluene levels. However, when the filters were turned off, pollution levels rebounded.
Ventilation can also provide temporary relief, but it is not a viable option when outdoor air remains unhealthy.
The most effective long-term solution is thorough cleaning. Researchers found that wiping down walls, ceilings, and all indoor surfaces significantly reduced VOC levels. Vacuuming and mopping proved more effective than air filters or open windows. However, the cleaning process must be comprehensive, covering both horizontal and vertical surfaces.
Chemical cleaners should be avoided, as they may react with VOCs and create more hazardous compounds. Instead, safe cleaning methods involve using water and non-reactive cleaning agents.
Restoring Safe Living Conditions
Recovering from a wildfire extends far beyond extinguishing flames. Toxic residues persist in the air, water, and soil, presenting long-term health risks. While official air quality readings may appear normal, localized contamination can still pose dangers.
By taking the right precautions—using proper protective gear, testing water and soil, and conducting thorough home cleaning—residents can reduce exposure and make their environments safer. However, given the complexities of post-wildfire contamination, ongoing research and policy improvements remain essential in mitigating future risks.
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