Even after wildfires are extinguished, the widespread use of plastics in the built environment and all other aspects of our lives worsens the long-term damage of wildfires to the natural environment, including to Earth’s soil, oceans and other water bodies, air, and climate.
The presence of plastic also fuels wildfires, makes wildfire smoke more toxic, and increases contamination of drinking water during and after wildfire disasters.
Toxic pollution from wildfires is made worse by plastic and can harm the health of people, the planet, plants, and wildlife for years or even decades. Here’s what you need to know to understand long-term wildfire pollution and environmental damage and how to best protect yourself.
Microplastics and Plastic Chemicals Harm Soil Health
Ashes from wildfires that burn across vegetated areas are usually helpful to the natural environment in the long term, returning nutrients like phosphorus and potassium to the soil that plants use to grow. However, wildfires that burn buildings and infrastructure contribute toxic chemicals to ashes that fall on soils. Soil toxicity from plastic-laced ash after wildfires harms everyone, but is acutely dangerous for farmers and people who grow their own food, and wild plants and animals.
Buildings today are typically made from significant amounts of plastics and other hazardous materials, such as lead paint, and are often filled with plastic household items like appliances, electronics, and furniture. When plastics and other hazardous materials and substances like cleaning agents, pesticides, and petrochemicals are burned, many of the chemicals they contain—like heavy metals, flame retardants, PFAS, phthalates, and polycyclic aromatic hydrocarbons (PAHs)—are transferred into ash. These chemicals leach into soils, and can even contaminate groundwater supplies when it rains.
Burning plastic also releases microplastics into the air and soils. Microplastics, which both absorb toxic chemicals from the environment and leach any mix of plastic’s more than 16,000 additives into the environment, along with toxic ash falling during and after fires, can cause long-term soil damage. Microplastics cause profound and serious harm to soil health by changing soil structure and water dynamics and reducing nutrient availability. Soil microbes are harmed by microplastics, and their loss reduces overall soil biodiversity and resilience. This can increase risk of soil pests and disease, and reduce plant growth by blocking plants’ water-absorbing pores and interrupting their water and nutrient uptake.
Soils are naturally less absorptive of water after wildfires in vegetated regions due to the loss of plant life and incorporation of ash into soils. Microplastics from burned plastics further decrease soil’s natural absorptive properties by making soils more compact and less permeable. Less absorption of water in soils following wildfires increases runoff as well as erosion, flooding, and landslides, particularly during heavy rainfall. On the other hand, dry, windy conditions can increase airborne toxic ash and microplastics by lifting these contaminants from soils during and long after wildfires. Experts say that even just walking through dusty areas coated in wildfire ash can release dangerous fine particulate matter and toxic chemicals into the air.
Burned Plastics Threaten Fresh Waters and Oceans
Ashes from large vegetative fires near water bodies can cause long-term damage to aquatic ecosystems when rain causes runoff to carry ash into lakes, oceans, rivers, or streams. When this happens, elevated levels of the nutrients nitrogen and phosphorus from burned plant matter can cause harmful algae blooms to form in waterways. This toxic algae can contaminate shellfish that cause paralysis or death for people who consume them; and pets have died from swimming in algae-filled waters.
Ash contaminated with microplastics and other hazardous manmade materials and chemicals creates additional dangers. Microplastics and plastic chemicals are not static; they travel far and wide through different ecosystems and elements—such as from air to soil to water—and even protected areas are subject to pollution.
Plastic chemicals and microplastics cause serious harm to aquatic ecosystems and the animals and plants that live in these environments. Microplastics pose both a chemical and physical danger to aquatic animals and plants, increasing their risks of disease, and reducing their lifespans and abilities to reproduce. Microplastics and plastic chemicals also threaten people who consume aquatic animals and plants, or work or recreate in freshwaters or the ocean. Many plastic chemicals are highly persistent, meaning, they accumulate and last for long periods of time in the environment without degrading. Plastic chemicals found in the ocean, which can be carried there from wildfire ash runoff, are known to damage humans’ and other animals’ nervous systems, increase cancer risks, interfere with normal hormone functions, and reduce fertility.
Burned Plastic Reduces Air Quality & Warms the Climate
Wildfires that burn across vegetated areas can cause long-term damage to air quality, including emission of substantial amounts of volatile and semi-volatile organic compounds (VOCs and SVOCs) and nitrogen oxides that form ozone and particulate matter. Emissions of these toxic pollutants can directly affect first responders and local residents, while also drifting across long distances, exposing populations far from wildfires for days to weeks.
Burning plastics exacerbate air quality issues during and after wildfires. When burned, plastics release toxic gases, particularly dioxins—which accumulate in the environment and can cause serious environmental and human health issues—as well as black carbon, heavy metals, particulate matter, PAHs, VOCs, and more. During the January 2025 wildfires in Los Angeles, California, levels of toxic airborne lead and chlorine released from burning manmade materials surged past long-term safety levels set by the U.S. Environmental Protection Agency.
Large wildfires cause significant release of carbon dioxide, black carbon, brown carbon, and ozone precursors into the atmosphere. This can affect the sun’s radiation, cloud formation, and therefore the climate on regional and global scales. Additionally, burning plastic emits high levels of greenhouse gases into the atmosphere: 2.9 kilograms of carbon dioxide equivalent for every kilogram of plastic burned. Plastic pollution, climate change, and the loss of biodiversity due to human activities are all interlinked issues driving major planetary change that threaten the future survival of people, plants, and animals alive today.
How to Protect Yourself
While the immediate threats of wildfire may diminish once fires are extinguished, long-term environmental threats can persist for months or years following a disaster. Research shows that dangerous chemicals and particles from wildfires can circulate in indoor air for months after fires. Washing surfaces and textiles can reduce their presence.
Children and pregnant people are especially vulnerable to the dangers of wildfire ash, smoke, and other lingering environmental contamination. Air pollution indoors and outdoors can lead to asthma and other respiratory problems, and also birth and reproductive problems such as stillbirth. Avoid spending time in areas with wildfire ash, or where wildfire ash has runoff in water bodies or the ocean, until local health authorities have declared them as safe.
Pay attention to wind advisories issued after wildfires to reduce your exposure to toxic windblown ash and stay indoors in a clean room if you have one, with a HEPA air filter on. Be sure to wear the appropriate N-95 mask when outside, and keep children and pets indoors. Remove clothes and shoes if exposed to ash or smoke before coming indoors.
Resources for People Affected by the 2025 Los Angeles Wildfires
Currently, federal, state, and local agencies are cleaning up the more than 16,000 homes and other structures damaged or destroyed in Altadena and Pacific Palisades, California. People without direct fire damage are expected to clean ash on their property.
Inhaling and ingesting wildfire ashes, and growing fruit and vegetables in them, can be hazardous to your health. Experts recommend removing the first six inches of soil from garden areas soon after fires are out and disposing of it in your trash. Be sure to wear boots, gloves, goggles or other eye protection, long-sleeve shirt, pants, and well-fitting N-95 mask or respirator while doing so. Do not put ash in compost or green bins. While it is not an ideal solution to trash this ash, removing it can help eliminate toxic pollution from your yard in the long term.
Other recommendations include:
- Avoiding the use of leaf blowers or other outdoor equipment that could stir up toxic ash; instead, gently sweep, HEPA vacuum, or wet-mop ash.
- Avoiding recreating in the ocean and other water bodies until the Los Angeles Department of Public Health clears water quality as safe.
- Conducting a soil test after cleanup to check for lingering toxins. Find a soil laboratory near you in Southern California.
- Wash any produce before eating, especially if it has direct contact with the ground. Soaking produce in one cup white vinegar to nine cups of clean water, then rinsing under running water can best remove ash.
Take Action
All of us, even those who are not immediately impacted by wildfires, face increasing health risks from our increasingly plastic- and chemical-filled landscape and culture. It is crucial that our government representatives protect people and the planet by holding polluters accountable with better pollution monitoring and regulation, and by mandating a drastic reduction in plastic and chemical production globally. A strong UN Plastics Treaty would expedite this necessary systems shift. Urge the leaders of the world’s biggest plastic polluting country—the U.S. Government—to support such an agreement to end plastic pollution today.
