Carbon monoxide emissions in the U.S. 1970-2023

In 2023, approximately 42.3 million tons of carbon monoxide (CO) were emitted in the United States – not including wildfire emissions. CO emissions in the U.S. have experienced a dramatic reduction since 1970, when 197.3 million tons were released into the atmosphere.

What is carbon monoxide?

Carbon monoxide is a toxic gas that is both odorless and colorless. It is released from the combustion of fuels such as coal, oil, and gas. It is the most abundant of the key air pollutants in the atmosphere and is harmful to human health. When breathed in, carbon monoxide reduces the amount of oxygen in blood, depriving the heart, brain, and other vital organs of oxygen. This can lead to nausea, headaches, dizziness, and at extremely high concentrations, death. Carbon monoxide poisoning is responsible for hundreds of unintentional deaths every year in the United States, though this is typically from indoor leaks.

Sources of carbon monoxide

Carbon monoxide can be released by numerous sources such gas stoves, tobacco smoke, or leaking furnaces. However, anthropogenic releases of carbon monoxide are chiefly from vehicle emissions. Prior to the 1970s, carbon monoxide emissions from transportation resulted in cities around the country exposed to high concentrations of this harmful pollutant. As the years went by, improved technology such as automotive catalysts, as well as clean air acts, helped to decrease CO emissions.