An air quality forecast, issued daily, is a one to two day prediction of air quality conditions. The air quality is expressed using an Air Quality Index (AQI). The air quality forecasting program works as a partnership between Environment Canada and the provinces.
Air Quality advisories are issued when the air pollution levels exceed national standards. They are issued in partnership with provincial and municipal environment and health authorities and contain advice on action that can be taken to protect the health of Canadians and the environment.
The Green LaneTM,
Environment Canada's World Wide Web Site.