Silent killer. Invisible threat. Unseen assassin.
These are all different—but accurate—names for carbon monoxide. And while none of these sound like something you'd want in your home, carbon monoxide poisoning remains the number one cause of poisoning deaths in the United States and sends thousands more to the emergency room each year.
Luckily, with the proper equipment in your home, carbon monoxide is detectable and CO poisoning is completely preventable.
What is carbon monoxide?
Carbon monoxide (also known as CO) is a toxic gas that is produced when materials containing carbon are burned. Coal, natural gas, kerosene, oil, and wood are common sources of carbon monoxide.
At home, household appliances and heating devices that emit carbon monoxide include:
- Fireplaces (both gas and wood-burning)
- Water heaters
- Furnaces
- Gas stoves and ovens
- Wood stoves
- Cars and other gas-powered vehicles
- BBQ grills, generators, and lawn equipment

Why is carbon monoxide deadly?
Carbon monoxide is so deadly because it is odorless, tasteless, and colorless. Unless you have a working carbon monoxide detector, there is no way to know if your home contains unsafe or deadly levels of carbon monoxide.
Symptoms of Carbon Monoxide Poisoning
In addition to a working carbon monoxide detector, knowing the symptoms of carbon monoxide poisoning is also important.
When CO is inhaled, it lowers the amount of oxygen carried to the brain, heart, and other organs. Low levels of exposure can present ongoing symptoms such as headaches, dizziness, weakness, nausea, and drowsiness. And because these symptoms can also be associated with many other illnesses, CO poisoning at lower levels may go unnoticed or get misdiagnosed.
At higher levels, carbon monoxide poisoning causes much more serious symptoms and can quickly lead to death. These symptoms include confusion, fainting, seizures, and a loss of consciousness. This can happen within minutes (which is also why most people who die of carbon monoxide poisoning do so in their sleep, before they even know what happened).