Air Quality & Smoke
En español →Smoke Kills More People Than Fire
Wildfire smoke is the fastest-growing air quality crisis in the western United States.
Smoke kills more people than fire does. An estimated 1,500–2,500 people die each year from wildfire smoke exposure in the western US (Burke et al. 2021, PNAS), more than die in the fires themselves. Newer estimates for the whole contiguous US are far higher (see below); they cover a larger area and long-term exposure, so the figures are not directly comparable. In 2020 alone, the Labor Day fires killed 11 people directly but wildfire smoke contributed to an estimated 6,300–8,800 excess deaths nationwide (O’Dell et al. 2023, GeoHealth).
Wildfire PM2.5 is not ordinary air pollution. A Southern California study of respiratory hospital admissions found it can be up to 10x more harmful to respiratory health per microgram than equivalent ambient PM2.5 (Aguilera et al. 2021, Nature Communications), a regional finding on respiratory outcomes, not a universal toxicity multiplier. The economic toll: $11–20 billion per year in health costs (Fann et al. 2018, EPA).
More recent causal work reinforces this. Two 2024–2026 studies attribute ~24,100 (Zhang et al. 2026, Science Advances) and ~11,415 (Ma et al. 2024, PNAS) deaths per year across the contiguous US to long-term smoke-PM2.5 exposure, with the mortality curve rising monotonically and no safe threshold — even low chronic exposure carries risk. These are chronic annual-average estimates, distinct from the acute day-of-smoke effects an AQI reading captures, so read them as a measure of the sustained toll, not a same-day threshold. One reporting nuance worth knowing: the rural western US sees the highest smoke concentrations, but large metro areas record more smoke-related emergency visits simply because more people are exposed (Jaffe et al. 2026, GeoHealth) — concentration and total health burden are not the same thing.
AQI from PurpleAir sensors: EPA-corrected 1-hour averages, updated at most once a day (last update: Sep 30, 2026, 9:11 PM PT); not NowCast, so values can differ from fire.airnow.gov, which you should use for current conditions. The smoke-impact layer has been withdrawn while we verify how it was built. For smoke forecasts see fire.airnow.gov and NOAA smoke forecasts.
Underlying air quality data utilized by PCSN is sourced from PurpleAir, a network of consumer sensors. Sensors are owned and managed by consumers, therefore PurpleAir does not guarantee data accuracy. All insights and claims are solely made by PCSN.
What to do at each level
During multi-day smoke events, cumulative exposure matters, even at moderate levels, take clean-air breaks (a filtered room, library, or community clean-air shelter) when smoke lingers for days.
USG = Unhealthy for Sensitive Groups. During major events AQI can exceed 500. Portland hit 500+ during the 2020 Labor Day fires.
Protect Yourself From Smoke
- •Only NIOSH-approved N95 or P100 respirators filter PM2.5. Surgical and cloth masks do not protect against wildfire smoke.
- •Create a clean-air room: a HEPA purifier, or a DIY box-fan filter (Corsi-Rosenthal box, roughly $40–100), in the room where you spend the most time.
- •Set HVAC to recirculate so it stops pulling smoky outdoor air inside.
- •Check live conditions at fire.airnow.gov and see the full preparedness guide at /prepare.
EPA AQS annual PM2.5 summaries (parameter 88101), ~700 monitors, 11 western states. PM2.5 > 35.5 μg/m³.
The smoke-impact layer has been withdrawn while we verify how it was built. The code and data that produced it, and the fit statistics previously quoted here, could not be traced, and its categories were not comparable with EPA AQI categories. For smoke forecasts see fire.airnow.gov and NOAA smoke forecasts (HRRR-Smoke).
The AQI layer on this page uses 10,700+ PurpleAir citizen science sensors across the western corridor, many times the density of the federal monitor network (about 700 monitors), filling critical gaps in rural fire-prone communities. Values are EPA-corrected 1-hour averages, updated at most once a day (last update: Sep 30, 2026, 9:11 PM PT); they are not NowCast, so they can differ from AirNow. For current conditions, use fire.airnow.gov.
18 uncontained large fires burn across 8 states; 157 active incidents in the western corridor (WFIGS). Snowpack at record lows across 8 of 11 corridor states. El Niño is established (weekly Niño 3.4 +0.5°C), with a 25% model share indicating a very strong event (≥+2.0°C) at the autumn peak. Key smoke risk factors:
AQI: PurpleAir (about 10,700 sensors, EPA-corrected 1-hour averages, updated at most once a day, last Sep 30, 2026, 9:11 PM PT; not NowCast); current AQI at fire.airnow.gov. Historical PM2.5: EPA AQS (2015–2025, 11 states, ~700 monitors). Health: Burke et al. 2021, O’Dell et al. 2023, Aguilera et al. 2021, Fann et al. 2018. Smoke-impact layer: withdrawn 2026-10-01 pending verification.