||Implications for health
||Air quality is considered satisfactory, and air pollution poses little or no risk.
||Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
||Unhealthy for Sensitive Groups
||Members of sensitive groups may experience health effects. The general public is not likely to be affected.
||Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
||Health alert: everyone may experience more serious health effects.
||Health warnings of emergency conditions. The entire population is more likely to be affected.