Air quality by ZIP

AQI (Air Quality Index)

EPA's 0-500 scale converting pollutant concentrations into a single index — Good (0-50) to Hazardous (301+).

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.

AQI thresholds — what 'unhealthy for sensitive groups' actually means for you

EPA's AQI uses six bands keyed to specific population groups. Here's what each band means at the personal-decision level — go outside, mask, stay home.

EPA AirNow — when to watch for particulates vs. ozone

AirNow's composite AQI hides which pollutant is dominant. PM2.5 and ozone behave differently — knowing which one is driving today's reading changes your response.

Extreme heat days + cooling equity — climate risk by ZIP

How NOAA + EPA track extreme heat, why cooling-system access varies dramatically by ZIP + income, and what 'cooling equity' means for property + insurance decisions.