Carbon Monoxide Pollution

Carbon Monoxide (CO) is a colorless, odorless gas. It forms during the incomplete combustion of fuels that contain carbon. Vehicle exhaust makes up more than 60% of all CO emissions nationwide, and is one of the most dominant pollutants in cities. CO can also come from forest fires, and its concentrations are the highest during cold weather. This is because cold temperatures make combustion less complete and cause temperature inversions which trap pollutants low to the ground.

Luckily, CO is quickly removed from the atmosphere by microorganisms in the soil. Small amounts of this gas are extremely dangerous. Poorly ventilated areas such as parking garages and highway tunnels are especially vulnerable areas because CO can kill without warning.

The Environmental Protection Agency uses its Air Quality Index to provide general information to the public about air quality and associated health effects. An Air Quality Index (AQI) of 100 for any pollutant corresponds to the level needed to violate the federal health standard for that pollutant. For carbon monoxide, an AQI of 100 corresponds 9 parts per million (averaged over 8 hours) -- the current federal standard.

EPA Air Quality Index	Levels of Health Concern	Cautionary Statements
0 - 50	Good	None
51 - 100	Moderate	None
101 - 150	Unhealthy for Sensitive Groups	People with cardiovascular disease, such as angina, should limit heavy exertion and avoid sources of CO, such as heavy traffic.
151 - 200	Unhealthy	People with cardiovascular disease, such as angina, should limit moderate exertion and avoid sources of CO, such as heavy traffic.
201 - 300	Very Unhealthy	People with cardiovascular disease, such as angina, should avoid exertion and sources of CO, such as heavy traffic.
301 - 500	Hazardous	People with cardiovascular disease, such as angina, should avoid exertion and sources of CO, such as heavy traffic; everyone else should limit heavy exertion.

CO enters the bloodstream when you inhale air. Usually your cells get oxygen through your hemoglobin (blood pigment), which carry it from your lungs throughout your body. Unfortunately, human hemoglobin prefer CO to oxygen, so if there is too much CO in the air your brain will become oxygen starved -- thus death may result.

• People with cardiovascular disease, such as angina, are most at risk from CO. These individuals may experience chest pain and more cardiovascular symptoms if they are exposed to CO, especially when exercising.
• People with marginal or compromised cardiovascular and respiratory symptoms, women that are pregnant, or small children, are most at risk from CO pollution.
• In healthy individuals, exposure to higher levels of CO can affect mental alertness and vision.

For detailed information about real-time pollution levels in the U.S., visit the Environmental Protection Agency's Website.