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Air Quality

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Carbon Monoxide

What is carbon monoxide?

Carbon monoxide (CO) is a colorless, odorless, tasteless gas that is slightly lighter than air. It is the most abundant pollutant in urban atmospheres and is very stable, having an average lifetime of 2-4 months in the atmosphere.

Where does CO come from?

The primary source of CO is incomplete combustion of fossil fuels used for transportation and heating. In Fort Collins, approximately 85% of the CO comes from motor vehicles and 10% comes from woodburning. Other sources include refuse and agricultural burning, natural forest fires, and by-products from some industrial sources. CO tends to build up when shallow cold air masses are trapped close to the ground by warmer air masses above and by the mountains to the west. These temperature inversions occur most commonly during fall and winter months.

How does CO affect human health?

Carbon monoxide pollution affects everyone. It affects the central nervous system by depriving the body of oxygen. CO enters the body through the lungs, where it is absorbed into the bloodstream. Hemoglobin in the blood combines much more readily with CO than with oxygen, thus the amount of oxygen delivered by the blood is reduced in the presence of CO. CO can cause headaches, fatigue, vision and judgment impairment, dizziness, and drowsiness. The severity of the effects depends on the concentration and duration of exposure. Carbon monoxide is of even greater concern at our high elevations where the air is thinner and has less oxygen.

Who is most at risk?

Particularly at risk are people with heart or breathing disorders, the elderly, pregnant women and their unborn children, and anemic individuals. Concern also exists for healthy children because of their increased oxygen requirements that result from their higher metabolism rate.

What are the EPA standards for CO?

The primary National Ambient Air Quality Standard (NAAQS) for CO are 9 ppm (parts per million) averaged over an eight hour period and 35 ppm averaged over a one hour period. The EPA allows no more than one exceedance of the standard per year for any given location. Subsequent exceedances constitute violations of the NAAQS.

Primary standards are designed to protect human health and secondary standards to protect human welfare. There are no secondary CO standards.

What are CO levels in Fort Collins?

Carbon monoxide has been monitored in Fort Collins since 1980. Concentrations are reported in the Fort Collins Air Quality Trends Reports. The downward trend in CO is due mostly to new car emission standards as well as oxygenated fuels and Colorado's inspection and maintenance program.

EPA Designation

Fort Collins is designated a maintenance area for CO. Between 1980 and 1991, the City violated the federal CO standard an average of six times per year and was therefore designated a non-attainment area for CO. In July 2002 the Colorado Air Quality Control Commission approved Fort Collins' Redesignation Request and Maintenance Plan, establishing Fort Collins as a CO "maintenance area."

For recent air quality measurements in Fort Collins, visit Air Pollution Control Division Sites. Under Monitor Data, select Reports. Under Single Stations, select "Fort Collins" or "Fort Collins South" (not Fort Collins VIS.) as the location, and the day you are interested in. Then click Display.