Federal Regulations: Winter Oxygenated Fuel Areas

The federal Clean Air Act Amendments of 1990 established a winter oxygenated fuels program to combat carbon monoxide emissions from vehicles.

Carbon monoxide (CO) is a colorless, odorless and poisonous gas produced by incomplete burning of carbon in fuels. When it enters the bloodstream, it reduces the delivery of oxygen to the body's organs and tissues. Health threats are most serious for those who suffer from cardiovascular disease, particularly those with angina or peripheral vascular disease. Exposure to elevated CO levels can cause impairment of visual perception, manual dexterity, learning ability and performance of complex tasks.

Beginning in 1992, gasoline sold during the winter months in areas designated as nonattainment areas for carbon monoxide pollution has to contain 2.7 percent oxygen by weight. The addition of oxygenates such as ethanol to gasoline significantly decreases carbon monoxide pollution. In fact, several areas have increased the minimum oxygen content to 3-3.5% by weight.

Ethanol is the oxygenate of choice in this program. It has been such a success that many areas are demonstrating attainment for carbon monoxide, and including the continued use of oxygenated fuel in their maintenance plan.

Click here to view a list of the winter oxygenated fuel areas.