Air Quality Index Categories and Examples

The Air Quality Index (AQI) is divided into six categories, each represented by a specific color and health advisory. Here are the categories along with example AQI values:

• Good (0 ‑ 50):25 
  
  Health Implications: Air quality is considered satisfactory, and air pollution poses little or no risk.


• Moderate (51 ‑ 100):75 
  
  Health Implications: Air quality is acceptable; however, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.


• Unhealthy for Sensitive Groups (101 ‑ 150):120
  
  Health Implications: Members of sensitive groups may experience health effects. The general public is less likely to be affected.


• Unhealthy (151 ‑ 200):180
  
  Health Implications: Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.


• Very Unhealthy (201 ‑ 300):250
  
  Health Implications: Health alert: everyone may experience more serious health effects.


• Hazardous (301 ‑ 500):400
  
  Health Implications: Health warnings of emergency conditions. The entire population is more likely to be affected.

A great deal of further information can be found here.