Utah Department of Environment Quality
The "Red Light, Green Light" program was created to prevent pollution build up by curtailing wood burning along the Wasatch Front during the winter inversions. Sometimes during winter months, a layer of cold air is confined within the Wasatch Front valleys by the surrounding mountains. Above the cold, dense layer is warm air. This creates an inversion that acts much like a lid, trapping pollutants within the cold air. In addition to the particulates emitted by automobiles, wood-burning stoves and fireplaces can also contribute to air pollution in Utah.

Fine particles such as those in soot and dust can become lodged in delicate lung tissue, decreasing lung function - a particularly hazardous situation for people with respiratory and cardiovascular diseases. Whenever pollution levels, measured by the amount of particulates in the air, reach a specific concentration, mandatory no-burn periods go into effect.

During the winter season, pollution conditions are announced to residents daily by newspapers and television stations. A Website and recorded message are also available for the public to receive daily updates. Wood-burning conditions are identified as:

Red Day
A "red" day means wood burning is prohibited. Residents are also asked to drive as little as possible on "red" days, and industries are asked to minimize their release of air pollutants.

Yellow Day
A "yellow" day means a voluntary no-burn or a recommended reduction in wood or coal burning. Residents are also asked to drive as little as possible on "yellow" days, and industries are asked to minimize their release of air pollutants.

Green Day
A "green" day means wood burning is allowed.