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Wildfire, Smoke & Air Quality

What Is the Air Quality Index (AQI)?

5 min read

The Air Quality Index, or AQI, is a public scale for communicating air pollution levels in a way that is easier to scan than raw pollutant measurements.

AQI categories use colors and labels to indicate increasing levels of concern for common pollutants, including fine particles during smoke events.

Informational only: HazardNow does not replace official alerts, warnings, evacuation orders, NWS, FEMA/IPAWS, state or local emergency agencies, utilities, or official instructions. Verify urgent decisions with authoritative sources.

What it means

The Air Quality Index, or AQI, is a public scale for communicating air pollution levels in a way that is easier to scan than raw pollutant measurements.

AQI categories use colors and labels to indicate increasing levels of concern for common pollutants, including fine particles during smoke events.

Why it matters

AQI helps people notice when air quality may affect outdoor activity, travel visibility, school operations, or the need to review official health recommendations.

During wildfire smoke, AQI can change quickly and may differ between monitoring stations.

What to watch

  • Current AQI category, pollutant driving the AQI, station freshness, and whether PM2.5 is elevated.
  • Wind shifts, wildfire detections, red flag warnings, and local health-agency messages.
  • Trends over several hours rather than a single number alone.

How HazardNow uses this signal

HazardNow summarizes AQI with wildfire, weather, and infrastructure context so air quality is not isolated from other disruption signals.

The dashboard is a starting point for awareness and source verification, not medical advice.

Limitations

HazardNow is informational only. For urgent decisions, protective actions, warnings, evacuations, closures, medical guidance, utility restoration, or travel instructions, follow official agencies and local authorities.

  • AQI stations may be sparse and can miss neighborhood-scale smoke.
  • Sensors and official monitors can report different values.
  • AQI categories do not replace public-health guidance or professional medical advice.

Related HazardNow pages

Live dashboardScan current public hazard and infrastructure signals.Wildfire smoke mapFire and smoke context.Air quality and wildfire smokeAQI and smoke monitoring guide.Data sourcesReview source families, update cadence, and limitations.

Official/public sources

These links are starting points for source verification. Local instructions, official alert text, and agency updates take priority.

AirNowAirNow AQI basics

FAQ

Is AQI the same as PM2.5?

No. PM2.5 is one pollutant measurement. AQI is a category scale that can be driven by PM2.5 or other pollutants.

Why can AQI apps disagree?

They may use different monitors, sensors, interpolation methods, refresh times, or pollutant calculations.