Air quality in Washington

EPA AQI categories explained — what 0–50 Good through 301–500 Hazardous mean

Plain-English guide to the six EPA Air Quality Index categories: 0–50 Good, 51–100 Moderate, 101–150 Unhealthy for Sensitive Groups, 151–200 Unhealthy, 201–300 Very Unhealthy, 301–500 Hazardous — what each level means and who is at risk.

AQI explained — what 50, 100, 150 actually mean for your lungs

Plain-English guide to the EPA Air Quality Index (AQI) and the 6 categories from Good to Hazardous. When to take precautions and which pollutants matter.

Wildfire Hazard Potential — what the USFS scale means and how to defend your home

Plain-English guide to the USDA Forest Service's Wildfire Hazard Potential 1–5 scale, how to read your community's risk, and concrete home-defense measures.

AirNow + wildfire smoke — when AQI is a real-time tool

How EPA AirNow handles real-time wildfire smoke, what the colors mean during fire season, and where AirNow leaves gaps you should know about.