Carbon monoxide is an odorless, tasteless, poisonous gas that forms when carbons from fuels burn incompletely. It is lighter than air and released both naturally, such as from forest fires and volcanic eruptions, and through man-made processes.

Some common man-made releases of carbon monoxide are from fumes of vehicles, small engines (like those in lawnmowers and generators), stoves, fireplaces and furnaces.

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Carbon monoxide poisoning occurs when carbon monoxide builds up in the blood. When too much carbon monoxide is in the air, the body replaces the oxygen in the red blood cells with carbon monoxide. This can lead to serious tissue damage, or even death.

Carbon monoxide is gas that has no odor, taste or color. Burning fuels, including gas, wood, propane or charcoal, make carbon monoxide. Appliances and engines that aren’t well vented can cause the gas to build up to dangerous levels. A tightly enclosed space makes the buildup worse.

Anyone exposed to carbon monoxide needs to get into fresh air and seek medical care right away. Call emergency medical services (EMS) or dial 911 right away for someone who’s in a coma or can’t respond.

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