Criteria Pollutant: Carbon Monoxide

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas. It is a by-product of incomplete combustion. In other words, it is emitted when wood, gasoline, coal and fossil fuels are burned incompletely. It is also emitted naturally when plants decay. Carbon monoxide can temporarily accumulate at harmful levels, especially during the calm, cool days of winter and early spring. That is when fossil fuel consumption is at its peak and is also when the gas is most chemically stable, due to low temperatures.

Carbon monoxide sources include:

• Automobiles. (Responsible for more than two-thirds of the man-made CO in the air. Levels are especially high in traffic congested cities due to the number of cars and the ability of tall buildings to trap the gas and keep it from blowing away. )
• Home/building heating
• Volcanoes, thunderstorms, and forest fires
• Vegetation during certain growth stages
• The chemical transformation of methane, a gas emitted from decaying plants. (Carbon Monoxide from natural sources usually dissipates quickly over a large area, posing reduced risk to health.)

Health Effects
Carbon monoxide reduces the amount of oxygen distributed throughout the body by the blood stream. Once carbon monoxide enters the blood stream, it attaches to hemoglobin, the substance that carries oxygen to the cells. The ability of CO to attach to hemoglobin occurs 200 times more readily than it does for oxygen. Low levels of oxygen and high levels of carbon monoxide:

• Affects the nervous system
• Weakens heart contractions, lowering the amount of blood distributed to body parts
• Reduces athletic performance
• Causes fatigue
• Causes shortness of breath and chest pain for people with heart disease
• Leads to irritability, headaches, rapid breathing, blurred vision, lack of coordination, nausea, dizziness, and impaired vision in normally healthy people

Young children, elderly, smokers, and those with pre-existing lung and heart diseases of more susceptible to carbon monoxide's negative health effects.

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