Los Angeles · January 2025
Where lead and ash from the Eaton and Palisades fires may have settled
When more than 16,000 buildings burned, lead and ash went into the air and came down across the county. This is our modelled estimate of where, shown as relative bands, with a plain account of how good it is and what county, EPA and CDC guidance says to do.
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How we estimated this
- Which buildings burned. CAL FIRE inspected every structure in the burn areas: 16,264 were destroyed (9,419 in the Eaton fire, 6,845 in the Palisades fire), and more were damaged. We matched them to county records for floor area and year built.
- When they burned. We timed each structure from satellite fire detections (GOES-18). These times are estimates, uncertain by several hours.
- How much material burned. Using published emission factors (Holder, US EPA, 2023), we estimate about 353,000 tonnes of burned material: about 146,000 in Eaton and 207,000 in Palisades.
- How much lead went into the air. Lead came from three sources in the model: old lead paint, other building materials (solder, PVC stabilizer, electronics) and vehicles. Our central estimate is about 9 tonnes released, with a range of about 4 to 15 tonnes. A separate published inventory (Schissel et al. 2026) gives 10 tonnes. We did not tune to it. The paint share rests on our assumptions.
- Where it went. We ran NOAA’s HYSPLIT model on NOAA’s 3 km weather analyses, hour by hour, from the first fire to 13 January. Particles settle by size. No rain fell until 26 January. Wind that lifted ash again was included to 27 January. About 2.4 of the 9 tonnes came down inside the map area. The rest drifted farther away or stayed airborne.
- Turning it into bands. We compare each 250 m square with the middle of the burn-area squares. Higher is more than twice that middle, about the same is between half and twice, and lower is down to one-fiftieth. Land below that is left uncoloured. This page publishes the band only, not an amount.
Ash follows the same steps. The time slider shows the running total landing over the week, in eight-hour steps to 15 January, then the final estimate through 27 January.
How good is it
Only one place measured lead hour by hour: the ASCENT monitor at Pico Rivera. At 8 AM Pacific time on 9 January it read 472 ng/m³. The highest 24-hour average was about 120 ng/m³, against a typical day of about 0.6 ng/m³ (Baliaka et al. 2026).
Here is how our model compares with that monitor, 8–11 January:
| Measure | Model | Measured | Reading |
|---|---|---|---|
| Four-day average | 38 | 57 | About two-thirds of the measured average |
| Highest 24 hours | 93 | 129* | About 70% |
| Main burst, Jan 9, 3–10 AM | 81 | 293 | The model misses most of it |
| Jan 11 episode | 0.9 | 64 | The model has no Jan 11 episode |
| Highest single hour | 653 | 472 | Not a match: the model’s peak is a one-hour pass of the plume, about 16 hours too early |
*Our calculation from the same ASCENT hourly data; the paper reports about 120. Four-day average is Jan 8–11, Pacific time.
In short: the model’s lead amount is in the right range and it gets about two-thirds of the four-day average, but it puts too much at Pico Rivera in one early hour, too little in the main burst, and none on 11 January. In the model the plume runs west of the monitor, not over it. Hour by hour, its rank correlation with the measurements is 0.40. The average is close partly because errors cancel.
Why the model missed 9 January
- In the early morning of 9 January the air in the basin was almost still: the observed average wind over the eleven stations between the fire and Pico Rivera was 1.4 m/s, with many calm readings.
- Satellites show smoke over Pico Rivera then (NOAA smoke outlines and GOES satellite smoke), matching the measured lead peak at 8 AM.
- The weather model we used (HRRR, 3 km) has a steady wind from the east-south-east at the fire, so our modelled plume left the fire about 90 degrees off the direction of Pico Rivera and only reached the monitor at the thin edge of a wide plume.
- Satellites show almost no burning of the destroyed streets that morning. The flare-ups after 9 January were almost all in wildland, such as the Mt Wilson fire on 9 January, which does not carry house lead.
- We tested fixes: releasing lead in step with satellite fire power made the match at Pico Rivera worse, and nudging the winds toward station readings moved the 9 January peak closer in time but did not turn the plume, add the 11 January episode or improve the hour-by-hour match.
The model is not a timing tool. It cannot tell you which hour smoke reached a place. Timing statements such as smoke reaching Pico Rivera at 5 to 9 AM on 9 January rest on the satellite and monitor data, not on the model. The lead amounts and the bands on the map are unchanged from this version.
The amount released is uncertain: about 4 to 15 tonnes, central about 9, against a published inventory of 10. Compared with county soil results, the model’s pattern matches moderately (rank correlation 0.665 across the 23 county intact-home sampling grids; bands ranked higher, about the same and lower had median measured lead of about 90, 57 and 36 mg/kg). That tests the pattern, not an amount. Our estimate of the people exposed above 50 ng/m³ (about 7 million) is similar to the paper’s 7 million (4.3 to 8.0), but it is not independent and we did not tune to it.
It does not predict indoor lead. Against the peak indoor dust-lead result in 180 tested Eaton-area homes (Eaton Fire Residents United), the model’s rank correlation was 0.15, almost no predictive value for a home. Do not use this map to judge a house.
No distance rule
Those 180 homes also show no distance pattern. By reported distance to the nearest burned structure, the median peak was about 95 µg/ft² in every group:
| Distance to nearest burned structure | Homes | Median peak, µg/ft² | Above 40 µg/ft² |
|---|---|---|---|
| Under 100 ft | 61 | 95 | 72–79% in each group |
| 100 to 750 ft | 67 | 100 | |
| Over 750 ft | 52 | 91 |
Eaton Fire Residents United data: homes chose to test (self-selected), tests were before cleanup, distance is as reported by residents, and each home shows its single highest result. Not a random sample.
This is why the map shows relative bands only, never a value for a street or a home, and why the zoom stops at neighborhood scale.
Where lead likely hit hardest
We looked at the Eaton fire area by area, keeping what was measured apart from what was modelled. Turn on “Eaton areas where lead likely hit hardest” on the map to see the approximate areas, numbered by rank. Area names and outlines are approximate boxes drawn around where destroyed structures were. They are not official neighborhood boundaries, and they show no individual homes.
- Measured: LA County soil sampling (sampled Feb 18 to Mar 26, 2025; summarized per area from the county’s 4.5 km grids), indoor dust reports from Eaton Fire Residents United (self-selected homes, areas with fewer than 5 homes left blank), and county ZIP results.
- Modelled: where our model puts the most lead, shown only as a rank among the seven areas. The order barely changed between model versions, though the amounts do change.
- County soil values include old paint and leaded gasoline lead as well as fire lead, so a high number is not proof of fire lead.
| Rank | Area (approximate) | Measured | Modelled (rank only) | Confidence | ||
|---|---|---|---|---|---|---|
| County soil, mg/kg | Indoor dust, µg/ft² | ZIP above 80 | ||||
| 1 | Central Altadena (Lake Ave to Altadena Dr, south)2,223 destroyed structures, 98% built before 1978 | 83 | 122 (98 homes) | 44% of 1,482 (91001) | top of the 7 | A two measured lines agree with the model.Model and measurements agree |
| 2 | West Altadena (Lincoln-Fair Oaks, south of Loma Alta)2,251 destroyed structures, 98% built before 1978 | 99 | 111 (51 homes) | 44% of 1,482 (91001) | top of the 7 | A two measured lines agree with the model.Model and measurements agree |
| 3 | East Altadena (Eaton Canyon edge)502 destroyed structures, 98% built before 1978 | 66 | 120 (55 homes) | 44% of 1,482 (91001) | lower half | A two measured lines agree with the model.Model and measurements agree |
| 4 | Northwest Altadena (foothill edge, Loma Alta-Lincoln)2,517 destroyed structures, 96% built before 1978 | 53 | 82 (39 homes) | 44% of 1,482 (91001) | upper half | C measured lines only partly agree with the model.Model and measurements disagree in part |
| 5 | NE Pasadena / Hastings Ranch (south of Eaton Canyon)201 destroyed structures, 83% built before 1978 | 76 | 110 (18 homes) | 24% of 155 (91107) | near the bottom | A two measured lines agree with the model.Model and measurements agree |
| 6 | North-central Altadena (Lake Ave foothills)1,763 destroyed structures, 98% built before 1978 | 58 | 75 (32 homes) | 44% of 1,482 (91001) | upper half | C measured lines only partly agree with the model.Model and measurements disagree in part |
| 7 | Sierra Madre west / Kersting Court side27 destroyed structures, 92% built before 1978 | not available | not available | 24% of 81 (91024) | near the bottom | D model only, no area measurement.No area-scale measurement |
Confidence is our own grade. The county soil grids are 4.5 km wide and the areas are 1 to 3 km, so area values are rough. Dust results are before cleanup.
Where the evidence agrees
Central and West Altadena are where the model and both measured lines agree best: about 2,200 destroyed structures each, 98% built before 1978, county soil of about 83 and 99 mg/kg, and indoor dust medians of about 122 and 111 µg/ft². East Altadena and the Hastings Ranch area of northeast Pasadena are smaller, and measured results there are higher than the model says.
Where the evidence disagrees
- Northwest Altadena and north-central Altadena: the model and the measurements disagree. The model puts them in the upper half, but measured soil and dust there are the lowest of the six Eaton areas with data. We do not call them hot spots.
- East Altadena and northeast Pasadena: measured results are higher than modelled. Our model smoke runs west of where monitors saw it, so it probably puts too little lead to the east and south-east.
- South of the main burned streets: the three highest county soil grids are there, where the model is also highest. Older-housing lead cannot be separated from fire lead with these data.
Pacific Palisades
We do not call any part of the Palisades a lead hot spot. The model ranks the Village and Alphabet Streets area highest there, but no area-scale measurement exists to confirm it, and LA County found no widespread fire-related soil lead in the Palisades (ZIP 90272: 7% of 101 samples above 80 mg/kg). That is why the Palisades areas are not drawn on the map.
Not available to us: area-scale soil results for the Palisades, northern Altadena above the foothills, Malibu and Topanga, and Sierra Madre (too few dust reports). This section gives no statement about any street or address.
What this means for you
We are not giving medical advice. Below is what the agencies say, with dates. Only a soil or dust test can tell you about one property. Being next to a burned lot is not the same as being downwind of one. Pick the path that fits you.
I’m rebuilding
- What the risk is
- LA County says lead in soil at the Eaton fire is reasonably expected to come from the burning of homes with lead-based paint, and that many other lead sources exist, so lead may predate the fires and tests may not separate sources. After the Army Corps removed soil, the county found a significant reduction in potential health risk where soil was removed, but parcels can still exceed screening levels both where soil was removed and where it was not (LA County Public Health final findings, Sep 12, 2025). The county says soil handling during rebuilding should consider how to manage surface soils to prevent exposure during construction and in final landscaping. Its results do not imply that cleanup is needed. The county’s report says soil checks belong in any rebuilding plan.
- Where it is more likely
- The county’s test results are higher in Altadena and northeast Pasadena than in the Pacific Palisades (table below), where it found no large-scale fire-related impacts, only two isolated areas with other chemicals, source not determined. We have no results by distance from burned structures. Older housing is more likely to have elevated soil lead, especially homes built before 1950, and lead can vary a lot within a few feet on one property (USC CLEAN, Aug 17, 2026).
- How to test, and when
- California DTSC’s guidance (Aug 2025) sets the timing by what happened to your lot:
- Total loss: test after the Army Corps (Phase 2) soil removal.
- Partial loss: test after debris is cleared.
- Standing home: any time.
- How to address a high result
- DTSC lists these options: cap the soil with clean soil or mulch (immediate and cost-effective); lay geotextile barriers; excavate and replace with clean fill (disposal rules apply); phytoremediation is emerging. UC ANR also suggests raised beds filled with clean soil for gardens. Re-test after cleanup or remodeling. The Army Corps removed at least the top 6 inches of soil only from the ash footprint of each burned structure, not yards or curbs, and lead can persist outside the building footprint after that removal (LA County report; USC CLEAN). After that removal EPA sampled 100 randomly chosen destroyed-home lots: 95 were below 200 mg/kg at the surface, median 31 mg/kg, and EPA says results would have been similar had 12 inches been removed instead of 6 (EPA Region 9, updated May 20, 2026). The county’s report suggests a professional assessment if lead is 80 mg/kg or more and children or pregnant people are at the property, and otherwise at 200 mg/kg or more. In California, anyone paid for lead inspections, risk assessments or clearance must be a CDPH-certified Lead Inspector/Assessor, and anyone paid to reduce lead hazards must be a certified Supervisor or Worker. A contractor’s license does not replace a CDPH lead certificate. Ask to see the card and get written lead-safe methods (CDPH). For burned-property debris, CDPH points to CalRecycle’s Wildfire Cleanup Guide.
- Who to call
- CDPH homeowner help line: 1-800-597-LEAD (5323). To verify a lead professional’s certification: (510) 620-5600.
- DTSC wildfire soil guidance: wildfireguidance@dtsc.ca.gov.
- Free blood lead test, LA County: 1-800-LA-4-LEAD (1-800-524-5323).
My home is still standing
- What the risk is
- At Eaton-area intact homes downwind of the fire, 10 of 23 sampling grids with intact homes averaged above DTSC’s 80 mg/kg, from 80.2 to 167 mg/kg. The county says this is consistent with its air results and with burning homes that had lead-based paint, but lead may predate the fires and many other lead sources exist (LA County Public Health, Sep 12, 2025). In the Palisades the county found no large-scale fire-related soil impacts. The county says screening levels are not cleanup levels and its results do not imply cleanup is needed.
- Where it is more likely
- Downwind of the Eaton fire, per the county. Being next to a burned lot is not the same as being downwind. Our map shows the modelled pattern in bands, not what is in your yard. The table below shows county test results by ZIP.
- How to test, and when
- For a standing home DTSC says test any time: top 6 inches, composite samples of the main areas, separate samples in gardens and play areas, and around the perimeter of homes built before 1978. Free testing: LA County Public Health’s Eaton Fire Soils Testing Program (self-collection; results by email with a link to health-based guidance; LA County, May 22, 2025), USC CLEAN, or CAP.LA. A blood lead test shows whether a child was exposed. CDC suggests considering one for ages 1 to 5 in a home built before 1978 or near a known lead source (CDC, Aug 21, 2025).
- How to address it
- Indoor dust results so far (all preliminary and from people who chose to test): in Eaton Fire Residents United’s 180 lead-tested homes, the median peak was about 95 µg/ft² and 75% of homes had a peak above 40. Peaks were on floors in 72 homes (93% above EPA’s 5 µg/ft² floor level), windowsills in 47 (66% above EPA’s 40 level) and attics in 15, where the median was highest, about 245. EPA’s levels come from its lead-paint program, not a fire rule, and these were pre-cleanup tests of the highest result per home. California has no standard yet for cleaning fire-affected homes.
- Caltech tested over 300 dust samples at 52 homes (preliminary, not peer reviewed): cleaning cut lead by up to 90%, and about 10% of cleaned surfaces were still above EPA’s limit. Lead was highest next to windows and doors.
- CDPH and UCSF looked at dust from 10 standing Altadena homes (20 tape lifts, preliminary): lead particles in 8 of 20. Five samples had round ultrafine particles that CDPH says indicate lead materials likely vaporized in a fire; three had larger irregular particles, likely old paint and building materials present before the fire. The method does not determine toxicity and cannot be compared with health standards.
- Attics: the state’s smoke-claims task force names attic vents among the ways ash gets in. Because there is no standard, CDPH and the county point to a certified industrial hygienist to decide on testing and a plan.
- Indoors: clean surfaces with a damp cloth; use a HEPA vacuum and a wet mop, no dry sweeping and no leaf blowers; a portable HEPA air cleaner where people spend the most time; remove shoes, use sticky mats; keep children away from ash and clean toys (CDPH, Safe Cleanup of Ash). EPA adds weekly wet cleaning of sills and door jambs and hand washing for children (updated Oct 14, 2026).
- Outdoors: wear an N95 respirator, gloves and long sleeves around ash; double-bag ash (CDPH).
- Soil: DTSC says protect your family by washing hands, shoes off, keeping children from bare soil, using raised beds and washing produce. Cap bare soil with clean soil or mulch.
- Pets: keep pets away from ash and shampoo them if they get ash on them (CDPH); wash or wipe paws (DTSC, EPA). For anything else, ask your vet.
- Food: wash garden produce thoroughly (CDPH, EPA); peel root crops and discard outer leaves of leafy greens (EPA).
- Who to call
- Free blood lead test, LA County: 1-800-LA-4-LEAD (1-800-524-5323). If you are pregnant or have questions about a result, ask a clinician.
- CDPH homeowner help line: 1-800-597-LEAD (5323); EPA lead information line: 1-800-424-LEAD.
- An environmental professional, for a specific property (LA County).
What county soil sampling found, by parcel type
| Parcel type | Eaton | Palisades |
|---|---|---|
| Destroyed: ash | 59.1% | 24.2% |
| Destroyed: soil | 33.9% | 10.8% |
| Destroyed, after Army Corps scraping | 27.1% | 2.7% |
| Destroyed, not scraped | 43.8% | 12.2% |
| Minor damage | 36.2% | 5.6% |
| No damage | 36.8% | 5.1% |
| Outside the fire boundary | 47.1% | 10.5% |
| Background (ambient) samples | 8.4% | 16.9% |
Outside the burn boundary and downwind, intact homes had the highest share above the screening level among homes that did not burn (47% of samples in the Eaton area). Scraping lowered the share on destroyed lots but did not remove it. Lead may predate the fires, and these results do not imply cleanup is needed.
What county soil tests found, by ZIP
| ZIP | Tests | Above 80 mg/kg | Above 200 mg/kg |
|---|---|---|---|
| 91106 | 15 | 93.3% | 26.7% |
| 91103 | 78 | 80.8% | 25.6% |
| 91104 Northeast Pasadena | 361 | 71.2% | 24.4% |
| 91001 Altadena | 1,482 | 44.1% | 7.6% |
| 91107 | 155 | 23.9% | 3.2% |
| 91024 | 81 | 23.5% | 6.2% |
| 90272 Pacific Palisades | 101 | 6.9% | 2% |
| 90265 | 18 | 5.6% | 5.6% |
80 mg/kg is the California DTSC residential screening level and 200 mg/kg is EPA’s (DTSC guidance, Aug 2025; EPA directive, Oct 16, 2025). A screening level is not a cleanup standard. Lead may predate the fires, and these county results do not imply cleanup is needed.
For scale, our model puts the largest soil addition from air-fall lead at about 0.6% of what county soil tests found. It does not cover burned lots, debris, ash left indoors, hard surfaces or old lead paint.
Nothing here says any yard or home is safe or unsafe. How the ZIP report cards elsewhere on PollutionProfile work is on the methods page.
Sources
- Baliaka et al. 2026, “Fire at the boundary: airborne toxic metals from the 2025 Los Angeles urban firestorm”, Science Advances 12(44), eaei4455. Link
- Schissel et al. 2026, “Fine spatial and temporal scale fuel and emissions inventories for the Eaton and Palisades WUI fires”, ACS ES&T Air 3(1), 156–164. Link
- Holder (US EPA) 2023, structure-fire emissions (EIC 2023 slides). Link
- ASCENT network (Caltech / Georgia Tech): hourly metals at Pico Rivera, Level 1b, NSF NCAR GDEX d389503, DOI 10.5065/52Y1-P893, CC BY 4.0. Link
- CDC MMWR 74(5), Notes from the Field: lead at Pico Rivera after the fires. Link
- CAL FIRE damage inspections (DINS) and incident pages, Eaton and Palisades fires. Link
- LA County Public Health, preliminary soil results, Apr 10, 2025. Link
- LA County Public Health and Roux, Community Soil Sampling and Human Health Screening Report (Sep 12, 2025), summarized on the county Post-Fire Assessment StoryMap, with the other task-force studies (CDPH + UCSF indoor dust, Sep 24, 2025; Caltech; EPA Region 9; USC CLEAN, Aug 17, 2026; Duke, May 18, 2026; CSUN, Mar 3, 2026). Link
- LA County Public Health, final findings bulletin, Sep 12, 2025. Link
- LA County, free Eaton Fire soil testing program, May 22, 2025. Link
- Eaton Fire Residents United, indoor lead test reports (201 homes, pre-remediation, Zenodo record 16762192, v0.1.0-beta, Aug 23, 2025, CC BY 4.0). Homes are self-selected; the group is an advocacy group. Link
- Caltech Science Exchange (Tissot lab), lead in dust, ash and water after the Eaton fire (Apr 2025; not peer reviewed). Link
- US EPA Region 9, Eaton Fire soil sampling of 100 destroyed-home properties (updated May 20, 2026). Link
- California Department of Insurance, Smoke Claims and Remediation Task Force report (Mar 9, 2026). Link
- US EPA, Actions to Reduce Potential Lead Exposure (updated Oct 14, 2026). Link
- US EPA, residential soil lead directive (Oct 16, 2025). Link
- CDC, Know the Facts: protect your child from lead exposure (page dated Aug 21, 2025). Link
- South Coast AQMD, After a wildfire: safe clean-up (fact sheet, undated). Link
- California DTSC, Residential Soil Evaluation guidance for the January 2025 fires (Aug 2025; copy of the agency PDF). Link
- CDPH, Safe Cleanup of Ash (page date not shown). Link
- CDPH, Find a Lead Professional (updated Aug 20, 2025) and Hiring a Certified Lead Professional (updated Jun 26, 2018). Link
- UC ANR Fire Network, After the Fire: Home Garden Soil Management (Feb 2026 update). Link
Map: PollutionProfile model, version 4 (run of 1 November 2026, central scenario). Basemap: OpenStreetMap contributors via OpenFreeMap. Lead figures from the model are estimates, not measurements.