An estimated total of 135 tons of CO are emitted during a typical weekday in the winter by all sources in the Anchorage bowl. About 84% of this CO is produced by cars and trucks. Most of the CO generated by motor vehicles is emitted during the first few minutes of operation. CO emissions are highest then because the engine is cold, the engine is operating rich, and the catalytic converter has not yet reached the operating temperature (about 600° F) necessary to convert carbon monoxide to carbon dioxide.

Other, less significant sources of CO are aircraft, and fireplaces and woodstoves. Very little CO comes from power generation or industrial sources in Anchorage.

For more information about CO emissions in Anchorage, review the previous indicator, Number of CO Air Quality Violations in Anchorage.