Carbon Monoxide Air Pollutant and Sources

A white cloud with the chemical formula for carbon monoxide, which is CO

Carbon monoxide, or CO, is a colorless, tasteless, odorless gas produced by the incomplete combustion of carbon-based fuels — including gasoline, diesel fuel, crude oil and wood — and other natural and synthetic products.

The main contributors of carbon monoxide emissions include vehicle exhaust from cars, trucks and buses; gas-powered furnaces; and portable generators. The greatest sources of carbon monoxide in outdoor air are cars, trucks and other vehicles or machinery that burn fossil fuels. More information is available on EPA's Carbon Monoxide Pollution in Outdoor Air webpage.

Missouri monitors CO concentrations in the air at locations across the state. Two of these sites are near roadways with heavy traffic in St. Louis and Kansas City. Click on the Air Monitoring Sites tab to learn more about these sites. Click on the Monitoring Data tab to learn more about the data collected from this sites.

For information about other ambient air pollutants that the department monitors, visit Air Pollutants and Sources.

Health Effects

Breathing air with a high concentration of carbon monoxide, CO, reduces the amount of oxygen that can be transported in the blood stream to critical organs like the heart and brain.

At very high levels, which are possible indoors or in other enclosed environments, CO can cause dizziness, confusion, unconsciousness and death.

Very high levels of CO are not likely to occur outdoors. However, when CO levels are elevated outdoors, they can be of particular concern for people with some types of heart disease. These people already have a reduced ability for getting oxygenated blood to their hearts in situations where the heart needs more oxygen than usual. They are especially vulnerable to the effects of CO when exercising or under increased stress. In these situations, short-term exposure to elevated CO may result in reduced oxygen to the heart accompanied by chest pain also known as angina.

Monitoring Data

Carbon Monoxide

Since 1971, EPA has maintained two standards for carbon monoxide: 35 parts per million (ppm) averaged over one hour and 9 ppm averaged over eight hours - not to be exceeded more than once per year. If design values are at or below the standard, then an area is in compliance. Design values correspond to an annual average of eight-hour concentrations and one-hour concentrations.

Preliminary one-hour CO data from sites, parts per million, CST

Preliminary eight-hour CO data from sites, parts per million, CST

Air Quality Analysis for Carbon Monoxide - Quarterly Report

Air Pollutant Design Values - Quarterly Report