(0-50)GoodNo health impacts are expected when air quality is in this range.
(51-100)ModerateUnusually sensitive people should consider limiting prolonged outdoor exertion.
(101-150)Unhealthy for Sensitive GroupsActive children and adults, and people with respiratory disease, such as asthma, should limit outdoor exertion.
(151-200)UnhealthyActive children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion.
(201-300)Very UnhealthyActive children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.
(301-500)HazardousHealth warning of emergency conditions: everyone is more likely to be affected.