Air Quality Index (AQI) Scale
The EPA uses 6 AQI categories to communicate air quality and associated health risks.
Good
Air quality is satisfactory, and air pollution poses little or no risk.
Health Impact: None
Recommendation: Enjoy outdoor activities freely. Air quality is considered satisfactory.
Moderate
Air quality is acceptable. However, there may be a risk for some people who are unusually sensitive to air pollution.
Health Impact: Unusually sensitive individuals may experience respiratory symptoms.
Recommendation: Active children and adults, and people with respiratory disease should limit prolonged outdoor exertion.
Unhealthy for Sensitive Groups
Members of sensitive groups may experience health effects. The general public is less likely to be affected.
Health Impact: People with heart or lung disease, older adults, children, and people of lower socioeconomic status are at greater risk.
Recommendation: Sensitive groups should reduce prolonged or heavy exertion outdoors. Schedule outdoor activities in the morning when ozone levels are lower.
Unhealthy
Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.
Health Impact: Increased likelihood of respiratory symptoms in sensitive individuals; aggravation of heart or lung disease.
Recommendation: Everyone should reduce prolonged or heavy exertion outdoors. Sensitive groups should avoid all outdoor exertion.
Very Unhealthy
Health alert: The risk of health effects is increased for everyone.
Health Impact: Significant aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; significant increase in respiratory effects in general population.
Recommendation: Everyone should avoid prolonged or heavy exertion outdoors. Sensitive groups should remain indoors and keep activity levels low.
Hazardous
Health warning of emergency conditions: everyone is more likely to be affected.
Health Impact: Serious aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; serious risk of respiratory effects in general population.
Recommendation: Everyone should avoid all outdoor exertion. Remain indoors and keep activity levels low. Run air purifiers if available.