Full Methodology
Estimate 01 — Direct Property Destruction
What it measures: The pre-fire market value of residential and commercial structures confirmed as Destroyed or Major Damage by CAL FIRE field inspectors.
What it does NOT measure: Land value · Contents and personal property · Infrastructure · Uninsured losses beyond structure value
Eaton Fire: 9,418 destroyed, 1,073 major damage
Total destroyed: 16,249 · Total major damage: 2,046
Altadena: $1,425,000
Eaton destroyed: 9,418 × $1,425,000 = $13.42B
Subtotal destroyed: $36.03B
Major damage: 2,046 × $2,367,500 × 50% = $2.42B
Lower bound: $36.0B
Upper bound (4% demand surge): $40.0B
Final range: $36B – $40B
- A1Neighborhood median prices used, not parcel-level assessments. Prop 13 constrained assessor values lag market values significantly.
- A2Palisades pricing applied to Palisades structures, Altadena pricing to Eaton structures.
- A3Major damage structures valued at 50% market price.
- A44% demand surge on upper bound only (vs Milliman's 15% — we use market value not replacement cost as base).
Milliman (Feb 2025): $25.2B–$39.4B insured losses only
UCLA Anderson (Feb 2025): $95B–$164B total economic
Our number sits above Milliman (includes uninsured) and below UCLA (narrower scope).
- Neighborhood medians mask bimodal value distribution
- DINS counts subject to revision
- Does not include contents, vehicles, infrastructure
- CAR medians based on transactions that may not represent all structure types
Estimate 02 — Property Value Impact
What it measures: Estimated decline in property values for surviving structures within 5 miles of fire perimeters.
What it does NOT measure: NOT additional to Estimate 01. Different properties only. Not permanent or cash-realized loss.
Sathaye et al. (2024), Landscape and Urban Planning — "Climate change and real estate markets: An empirical study of the impacts of wildfires on home values in California"
Method: Quasi-experimental spatial panel models with propensity score matching.
Key finding: 2.2% average property value decline within affected zone.
Total market value: ~$175B
Depreciation rate: 2.2%
Calculation: $175B × 2.2% = $3.85B
Final estimate: $3.9B
- A12.2% used as single point estimate. Higher values (8%+) not supported by literature for this parameter.
- A2Post-fire CAR distressed sales data (Altadena -39.1%, Palisades -23.7%) NOT used — reflects forced lot sales only, not typical residential transactions.
- A35-mile radius is product simplification, not a fixed academic threshold.
- A4$175B housing stock is approximate, derived from LA County Assessor parcel counts and Zillow Research CSV data.
- 2.2% is average across many fires — 2025 LA fires may exceed this given urban intensity
- Paper loss may partially recover
- Study sample may not include events of this scale
- No distance-decay model applied within the zone
Estimate 03 — Acute Smoke Health Cost
What it measures: Economic cost of PM2.5 exposure to 4.2M LA County residents during 14-day elevated smoke period. Health economic cost — NOT property loss. Must not be added to Estimates 01 or 02.
Why included: SmokeStory's unique contribution. No other published LA wildfire estimate includes smoke health cost. Calculated directly from SmokeStory PM2.5 sensor data.
EPA 2024 standard: 9.0 µg/m³
Excess: 35.8 µg/m³ = 3.58 units of 10 µg/m³
Duration: 14 days
Exposed population: 4,200,000
Acute admissions (65+, 800K): 0.17% × 3.58 = 4,869 cases
ER visits (all ages, 4.2M): 0.24% × 3.58 = 36,086 visits
Asthma attacks (450K patients): 3.0% × 3.58 = 48,330 attacks
Work loss days (4.2M): 0.046 × 3.58 = 691,656 days
Restricted activity (4.2M): 0.072 × 3.58 = 1,082,592 days
Admissions: $40,000/case → $194.8M
ER visits: $1,200/visit → $43.3M
Asthma attacks: $220/attack → $10.6M
Work loss days: $280/day → $193.6M
Restricted activity: $96/day → $103.9M
Base total: $546M
Final range: $0.5B – $1.0B
(Upper bound accounts for monitor coverage gaps, higher incidence in vulnerable communities)
- A1COI method used, not VSL. VSL designed for chronic long-term exposure, not acute 14-day events.
- A214-day duration is conservative — some monitoring stations recorded longer periods of elevated PM2.5.
- A3Population-average BenMAP incidence rates applied.
- A4Uniform exposure assumed across 4.2M zone.
- COI excludes mortality risk — deliberate conservative choice
- Wildfire PM2.5 may be more harmful per µg/m³ than general rate (toxic ash compounds)
- AQS data preliminary — final QA available 6+ months post-collection
- National incidence rates applied to LA County
Data Sources
| Source | Used For | Access |
|---|---|---|
| CAL FIRE DINS (Feb 5, 2025) | Structure counts | public fire.ca.gov |
| CAR 2024 | Pre-fire prices | public reports |
| Zillow Research CSV | Housing stock value | free zillow.com/research/data |
| LA County Assessor Open Data | Housing stock count | public data.lacounty.gov |
| Sathaye et al. 2024 LUP | Depreciation rate | peer-reviewed journal |
| EPA AQS Param 88101 | PM2.5 readings | public API via SmokeStory |
| EPA BenMAP TSD Jan 2023 | Health impact functions | public epa.gov/benmap |
| EPA BenMAP COI 2023 | Economic unit values | public epa.gov/benmap |
| BLS 2024 LA County | Work loss valuation | public bls.gov |
| CHIS 2021–2022 | Asthma population | public UCLA CHIS |
| CAL FIRE FRAP | Map perimeters | public GeoJSON |
| NOAA HMS | Smoke layer | via SmokeStory |
Methodology Version 3.0 · github.com/tinahuang1994/smokestory