Which states have the best and worst air quality?

The average air quality in Arizona is considered unhealthy, while Hawaii has the country’s best air quality.

These designations are based on air quality index (AQI) which indicates the number of pollutants in the air. According to the Environmental Protection Agency, an AQI of less than 50 is considered “good,” an AQI of 51–100 is “moderate,” and 101–150 is “unhealthy for sensitive groups.”