The air quality is considered satisfactory, and air pollution poses little to no risk.
No restrictions are recommended.
The air quality is acceptable. For a small number of sensitive people there may be a moderate health concern.
Active children, adults and people with respiratory disease should limit longer outdoor exposure.
The air quality is moderate. Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Active children, adults and people with respiratory diseases should limit outdoor exposure.
The air is unhealthy. Everyone may begin to experience health effects. The members of sensitive groups may experience serious health effects.
Active children, adults and people with respiratory diseases should avoid outdoor exposure. Everyone else should limit outdoor activities.
The entire population is likely to be affected while sensitive groups may experience serious health effects. Everyone should limit outdoor exposure especially children and people with respiratory disease.