Wildfire Ash and Metals: What the Eaton and Palisades Soil Testing Found

Testing after the early-2025 Los Angeles fires found metals, mostly lead, in some ash and soil, unevenly spread. Los Angeles County reported that 10 of 23 sampling grids with intact homes downwind of the Eaton Fire averaged lead above its screening level, and that the Palisades region showed no large-scale fire-related soil impacts [1]. EPA’s later sampling of 100 Eaton Fire properties found 98 below its 200 mg/kg lead screening level at 6 to 7 inches and 95 below it at the surface [2]. Hawaii’s 2023 testing of Lahaina ash found arsenic and lead well above soil action levels [3]. Each answers a slightly different question, so below is each result with its source and limits.

Every number is attributed to the agency or paper that reported it, and none of it is a verdict on a specific property. For fire recovery generally, see after the fire and our wildfire burn scars profile.

Ash and soil are different samples

A burned building leaves structural ash that can hold metals from paint, roofing, wiring and other materials. The soil underneath may or may not have picked those metals up. Testing programs sample ash, soil or both and compare results with soil screening levels, so the first questions about any result are what was sampled and what it was compared with.

Los Angeles County testing (Eaton and Palisades)

Los Angeles County Public Health released final findings on September 12, 2025 [1]. Its contractor, Roux Associates, sampled soil and ash between February 18 and March 26, 2025, for heavy metals, polyaromatic hydrocarbons and dioxins/furans, at destroyed properties, intact properties and properties just outside the burn areas. Results were compared with California Department of Toxic Substances Control (DTSC) residential soil screening levels [1].

In the Eaton Fire area, of 70 sampling grids, 23 had intact homes, and 10 of those 23 averaged lead above the DTSC residential screening level of 80 mg/kg, with averages from 80.2 to 167 mg/kg. The county said the lead is reasonably expected to come from burned homes with lead-based paint, common before 1979, noting that more than 70% of houses in the region predate 1979. It added that the Los Angeles area has many lead sources, so further assessment could clarify how much came from the fires [1].

The Palisades Fire showed no large-scale fire-related soil impacts, lead included, although two isolated areas exceeded levels, one for cadmium and thallium and one for arsenic and PAHs, with source and fire connection unknown. The county said the pattern didn’t fit communitywide impacts from smoke plumes [1].

On parcels with destroyed structures, after Army Corps of Engineers soil and debris removal, results showed a significant reduction in potential health risk where removal occurred. These parcels can still have spots above residential screening levels, both where soil was removed and where it wasn’t, and some impacts may be unrelated to fire [1].

The county stated the results don’t imply cleanup is necessary. They are public-health data for finding areas that may need more evaluation, and anyone with concerns can test their soil or consult an environmental professional [1].

EPA’s Eaton Fire sampling

EPA announced results on May 19, 2026, under the headline that its Eaton Fire soil sampling confirmed federal cleanup protocols effectively remediated burn debris contamination [2]. It sampled 100 randomly selected properties with 4,200 borings at two depths, 0 to 1 inch and 6 to 7 inches. Against a residential lead screening level of 200 mg/kg, 98 of 100 properties were below at the subsurface depth and 95 of 100 at the surface. Median lead was 31 mg/kg at the surface and 21 mg/kg below. EPA cited a 2025 Los Angeles County study finding lead the only fire-related soil contaminant of concern across the Eaton Fire area, and noted that results vary property to property and lead may reflect older releases unrelated to the fire [2].

A peer-reviewed study of ash and soil

Duke University researchers and trained volunteer homeowners collected about 300 soil and ash samples from more than 30 burned residences in early 2025. The paper, Dossou et al. in Environmental Science & Technology Letters (2026), reports highly variable lead and arsenic, with the highest lead in structural ash from a fraction of homes built before the 1970s, likely from lead-based paint [4]. A press summary adds that resampling at 17 residences after cleanup, with more than 100 more samples near the original sites, showed much lower lead and arsenic in scraped areas, especially where levels had been highest. The senior author notes the Army Corps did no post-cleanup testing after these fires, so before-and-after comparisons like this are uncommon [5].

Lahaina (Maui, 2023)

The Hawaii Department of Health tested ash from 100 Lahaina properties on November 7 and 8, 2023, and released the data on December 10, 2023, comparing means with its soil environmental action levels [3]:

DOH advised against disturbing ash, recommended protective equipment in affected areas, and urged keeping surfaces clean [3]. After the Army Corps removed debris, DOH ran confirmatory soil sampling. It set the arsenic cleanup goal at 41 mg/kg to reflect how bioavailable arsenic is to people, and its residential action level for lead is 200 mg/kg [6].

The numbers side by side

They differ because they ask different questions:

• California’s 80 mg/kg lead level sits below EPA’s 200 mg/kg, so a grid can exceed one and not the other.
• Ash isn’t soil, and a surface sample isn’t a 6-inch sample.
• Intact homes, destroyed homes and cleaned parcels each give different results.
• Timing matters, because soil scraping changes what is left.
• The purpose differs too, and EPA says its regional screening levels are not cleanup standards [7].

Biology’s role here

Lead and arsenic are elements, so microbes can’t destroy them. They can change a metal’s chemical form, bind it, or help plants take it up; heavy metals in soil explains each. After these fires the cleanup method was removing debris and soil [1][3], and biology comes in afterward to rebuild structure and cover on cleared land. For lead, see lead in soil and the urban lead soils profile. The contaminant profile is at heavy metals.

Open questions

The long-term pattern of metals in rebuilt neighborhoods, how much lead predates the fires, and what untested properties hold are all still unknown. The county noted individual parcels can differ from its representative samples [1], and the Duke study’s 30-plus volunteer-sampled homes describe those homes, not the region [5]. If you manage land or a program in a fire-affected area and need help reading soil results, write to us.

Sources

All links checked 2026-10-01.

1. Los Angeles County Department of Public Health. Public Health Releases Final Findings of Soil Testing in Fire-Impacted Areas. Press release, September 12, 2025. publichealth.lacounty.gov
2. U.S. EPA. EPA’s Eaton Fire Soil Sampling Confirms Federal Cleanup Protocols Effectively Remediated Burn Debris Contamination. News release, May 19, 2026. epa.gov
3. Hawaii Department of Health. Lahaina Ash Characterization Testing Show Elevated Levels of Toxic Substances. News release, December 10, 2023. health.hawaii.gov
4. Dossou SA, Kelly L, Lu PL, Jones R, O’Donnell O, Walsh JSP, Richter DD. Urban conflagrations: structural ash and soil metal(loid) contamination after California’s Eaton and Palisades fires. Environmental Science & Technology Letters 13(6):818 to 824 (2026). doi:10.1021/acs.estlett.6c00268
5. Phys.org. Burned-home soils showed uneven lead, arsenic contamination after Los Angeles wildfires. June 2026. phys.org (press summary of source 4; consult the paper for full methods)
6. Hawaii Department of Health. Residential confirmatory soil sampling, Maui wildfires. health.hawaii.gov
7. U.S. EPA. Regional Screening Levels (RSLs). epa.gov