B.C. Air Quality

Air and Airsheds in B.C.

Airsheds

An "airshed" or "air basin" is an area in which the terrain and weather conditions hinder the movement of pollutants away from the area.

A mountain valley is a common example of an airshed in British Columbia These areas frequently experience temperature inversions, in which the air near the ground is colder than the layer of air above. This results in very stable conditions within the valley, such that pollutants released near the surface are confined to the airshed. In turn, these stable conditions can lead to high levels of air pollution. Many B.C. communities have periods of unacceptable air quality, with adverse effects on human health, the environment and visibility.

The complex terrain and weather patterns in B.C. naturally divide the province into a number of airsheds, such as the Lower Fraser Valley, Okanagan Valley and Bulkley Valley. The larger Georgia Basin / Puget Sound airshed, which includes the Lower Fraser Valley, lies along the western coast of Canada and the United States.

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