The Centers for Disease Control and Prevention (CDC) says carbon monoxide (CO) is a gas with no odor or color, and breathing it can cause sudden illness and death. The CDC and the U.S. Consumer Product Safety Commission (CPSC) both publish steps meant to reduce the risk of CO poisoning at home. This explainer reports what those two agencies say.

Where carbon monoxide comes from

According to the CDC, CO is found in fumes made whenever fuel is burned in furnaces, gas ranges, fireplaces, grills, lanterns, stoves, small engines, cars or trucks. The agency says gas- and oil-burning furnaces, portable generators and charcoal grills are among the household items that produce it. The CDC says indoor buildup of CO can poison any people or animals breathing the air.

The CDC says everyone is at risk. It says people more likely to become ill from CO include infants, elderly people, and those with long-term heart disease, anemia or breathing problems. As of the page’s Oct. 26, 2026 update, the CDC says more than 400 Americans die each year from unintentional CO poisoning not linked to fires. It also reports more than 100,000 emergency department visits and more than 14,000 hospitalizations each year.

Symptoms of CO poisoning

The CDC lists the most common symptoms as headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion. It says they are often described as “flu-like.” The CPSC says the early symptoms of low to moderate poisoning resemble the flu but without the fever. It lists headache, fatigue, shortness of breath, nausea and dizziness.

The CPSC says high-level poisoning causes progressively more severe symptoms. These include mental confusion, vomiting, loss of muscular coordination, loss of consciousness and, ultimately, death. It says severity is related to both the CO level and how long the exposure lasts.

Both agencies warn that CO can be hard to notice. The CDC says people who are asleep, intoxicated or affected by other substances can die before symptoms appear. The CPSC says people may mistake mild to moderate symptoms for the flu. It adds that in rapidly developing, high-level exposures, such as generator use in residential spaces, victims can become confused and lose muscle control without first having milder symptoms.

CO detectors and alarms

The CDC advises installing battery-operated or battery backup CO detectors near every sleeping area in the home. The CPSC advises placing CO alarms that run on batteries, or that have battery backup, on each level of the home and outside sleeping areas. The CPSC says interconnected alarms are best because when one sounds, they all sound.

The CDC advises checking detector batteries when clocks are changed each spring and fall. It also advises replacing a detector following the manufacturer’s instructions or every five years. The CDC notes that a detector with a digital readout can show the highest level of CO concentration in the home, in addition to sounding an alarm.

Furnaces, appliances and chimneys

The CDC advises that a qualified technician service the home’s heating system, water heater and any other appliance that burns gas, oil or coal once a year. The CPSC similarly advises having home heating systems, including chimneys and vents, inspected and serviced every year by a trained service technician. The CDC also advises having a chimney checked or cleaned every year, because debris can block it and cause CO to build up inside a home or cabin.

The CDC says gas appliances should be vented properly. It says horizontal vent pipes, such as those for a water heater, should go up slightly as they go toward the outdoors. This prevents CO from leaking if the joints or pipes are not fitted tightly. The CDC also says that anyone purchasing gas equipment should choose only products bearing the seal of a national testing agency, with Underwriters’ Laboratories given as an example.

The CDC says a house should never be heated with a gas oven. The CPSC says a gas range or oven should never be used for heating. The CDC adds that nothing should be cooked or burned on a stove or fireplace that is not vented. It says an odor from a gas refrigerator can mean it is leaking CO and should be serviced by an expert. The CPSC advises opening the fireplace damper before lighting a fire and keeping it open until the ashes are cool. It says an open damper may help prevent a build-up of poisonous gases inside the home.

Generators, grills and vehicles

The CDC and the CPSC both say a portable generator should never be used inside a home or garage, even if doors and windows are open. The CDC says generators should be used only outside, more than 20 feet from any windows, doors and vents. The CPSC says generators should be used outside only, at least 20 feet from homes, with the exhaust facing away. The CDC adds that a battery-powered or battery backup CO detector should be used in the home when a generator is running.

The CDC says burning charcoal of any color gives off CO and should never be done indoors. It also says a portable gas camp stove should never be used indoors, and portable flameless chemical heaters should not be used indoors. The CPSC says a charcoal grill should never be brought into the house for heating or cooking, and that barbecuing in the garage should not be done.

For vehicles, the CDC advises having a mechanic check the exhaust system of a car or truck every year. It says a small leak can lead to CO building up inside the vehicle. The CDC says a car or truck should never be run inside a garage that is attached to a house, even with the garage door open. For a detached garage, it advises opening the door to let in fresh air.

The CDC also says that when the tailgate of a car or SUV is open, the vents or windows should be opened so air moves through. If only the tailgate is open, it says, CO from the exhaust will be pulled into the vehicle. The CDC asks anyone who has had a poisoning incident related to a generator to let the CPSC know, and the CPSC provides a way to report an unsafe product.