Compound Signal
Wildfire Burden — acute and chronic smoke exposure
Wildfire smoke exposure × Respiratory-vulnerable population
50 counties are firing this signal at the elevated threshold (≥70/100) right now.
What it measures
Six-component blend that captures both the acute (active fires + AQI exceedance) and chronic (Stanford Childs/Burke wildfire-attributable PM2.5 mean + smoke days) sides of wildfire-smoke exposure, scoped to population vulnerability and pulmonology supply. The merged successor (methodology v1.5/v1.8) to the legacy Wildfire Smoke Vulnerability and Wildfire-Attributable Burden signals, which shared two of four components and cannibalized each other.
Component breakdown
Each component is independently percentile-ranked against all US counties (0–100), then blended into the final signal score using the weights below.
| Component | Weight | Source |
|---|---|---|
| Active fires within 200km | 12.5% | NIFC / WFIGS |
| 30-day max AQI | 12.5% | EPA AQS daily |
| Annual mean wildfire-PM2.5 | 15% | Stanford Childs/Burke (Harvard Dataverse 10.7910/DVN/DJVMTV) |
| Smoke days >55 µg/m³ | 15% | Stanford Childs/Burke |
| Asthma + COPD blend (60/40 dominant) | 25% | CDC PLACES |
| Pulmonology access deficit | 20% | NPPES (inverted percentile) |
Evidence base
EPA AQS classifies wildfire-PM2.5 as 'exceptional events' and excludes it from official readings, undercounting exposure by 10–30% in fire-affected counties (Burke et al, Nature 2023). The Stanford Childs/Burke product was built specifically to fill that gap and is the basis for Ma et al PNAS 2024 (~11,415 non-accidental deaths/year attributable to wildfire smoke) and Qiu et al Nature 2025 (projected ~71,420 deaths/year by 2050). The acute legs (fires + AQI) capture observed recent-event response; the chronic legs (smoke mean + smoke days) capture long-term burden the AQS network misses; the population leg (asthma + COPD) and capacity leg (pulmonology) close the loop on who is exposed and who can treat them.
Childs et al, EST 2022
Childs ML, Li J, Wen J, et al. Daily local-level estimates of ambient wildfire smoke PM2.5 for the contiguous US. Environmental Science & Technology. 2022;56(19):13607-13621.
Burke et al, Nature 2023
Burke M, Childs ML, de la Cuesta B, et al. The contribution of wildfire to PM2.5 trends in the USA. Nature. 2023;622(7984):761-766.
Ma et al, PNAS 2024
Ma Y, Zang E, Liu Y, et al. Long-term exposure to wildland fire smoke PM2.5 and mortality in the contiguous United States. PNAS. 2024;121(40):e2403960121.
Coverage caveat
Chronic legs are CONUS only (Stanford V1, 2006–2020). Counties in AK, HI, PR, VI, and GU score on the acute legs alone.
Counties firing this signal
Top 50 counties at the elevated threshold (70/100) or above, sorted by score. Click any county for the full profile.
Related service line: respiratory. The platform tool exposes per-county service-line opportunity scores on Pro, Studio, and Enterprise tiers.
Methodology
Every Compound Signal on this platform is a versioned, weighted composite published transparently. See the full methodology — every weight, every threshold, every data source — on the methodology page.
View full methodology →