Indoor Heat and the Danger of Carbon Monoxide

Each year, more than 500 people die from unintentional CO poisoning.
- Centers for Disease Control

As winter approaches, families tend to spend more time indoors and, inevitably, turn up the thermostat. Most of us are well aware of the risk of fire from portable heaters, wood stoves or mattresses jammed up against hot radiators. Working smoke detectors are a must at this time of year.

But what many households still lack, in spite of increased public safety warnings, are carbon monoxide (CO) detectors and, more important, regular inspections and maintenance of furnaces, gas water heaters, space heaters, ovens, fireplaces and wood stoves. Each year in the United States, more than 500 people die from unintentional CO poisoning, according to the national Centers for Disease Control (CDC). Fetuses, infants, the elderly and people with anemia or a history of heart or respiratory disease are particularly at risk.

Carbon monoxide is a colorless, odorless gas produced when any fuel is incompletely burned, including natural gas, propane, heating oil, kerosene, coal, charcoal, gasoline and wood. It can leak from a faulty furnace or fuel-fired heater; it can build up in fireplaces with a blocked chimney or flue, and it can seep into the house from a car left running in an attached garage.

CO poisoning is easily mistaken for the flu or even food poisoning, since its symptoms are similar - dizziness, fatigue, headaches, nausea and irregular breathing.

While the CDC and the Environmental Protection Agency (EPA) both recommend that families purchase CO detectors (and some states now require them in homes and businesses), these agencies also caution families not to rely solely on the detectors for protection. In laboratory tests, performance of CO detectors has varied widely, according to the EPA.

Better to first make sure that your home heaters, furnaces, fireplaces and ovens are inspected annually for leaks, proper ventilation, cleanliness and efficiency. Choose appliances that vent fumes to the outside, and keep vents clear of lint, dirt, snow, ice and other debris.

In addition, the EPA warns families to:

  • Never leave a car idling in the garage, even when the garage door is open.

  • Never use a charcoal grill indoors.

  • Never use a gas oven to heat a home.

  • Never sleep in a room with an unvented gas or kerosene space heater.

  • Never ignore the symptoms of CO poisoning, especially if more than one person is experiencing them.

If you do suspect CO poisoning, get fresh air immediately. Head to an emergency room to be checked for possible poisoning - it can often be diagnosed by a blood test soon after exposure.

For more information on CO poisoning prevention, visit  or

- Deirdre Wilson

More EPA Resources:

Protect Your Family and Yourself from Carbon Monoxide Poisoning [EPA 402-F-96-005, October, 1996]

Discusses health hazards associated with exposure to carbon monoxide (CO), a colorless, odorless gas which can cause headaches, dizziness, nausea, faintness, and, at high levels, death. Provides guidance on what to do if you think you are suffering from CO poisoning and what to do to prevent exposure to CO. Also included is a brief discussion about carbon monoxide detectors.

Proteja su vida y la de su familia evitando el envenenamiento con monóxido de carbono [EPA 402-F-97-004]

This fact sheet has also been translated into Vietnamese [EPA 402-F-96-005C], Chinese [EPA 402-F-96-005A], and Korean [EPA 402-F-96-005B]. To get copies of any of these, contact IAQINFO at 1-800-438-4318.

ALERT!! Preventing Carbon Monoxide Poisoning from Small Gasoline-Powered Engines and Tools. (1996)

This joint alert from NIOSH, CDPHE, CPSC, OSHA and EPA warns that people using gasoline-powered tools such as high-pressure washers, concrete cutting saws (walk-behind/hand-held), power trowels, floor buffers, welders, pumps, compressors, and generators in buildings or semi-enclosed spaces have been poisoned by Carbon Monoxide. Recommendations for preventing CO poisoning are provided for employers, equipment users, tool rental agencies, and tool manufacturers.

Single copies of the Alert [DHHS (NIOSH) Publication No. 96-118] are available for free from:  Publication Dissemination, IED, National Institute for Occupational Safety and Health; 4676 Columbia Parkway, Cincinnati, OH 45226
fax number: (513) 533-8573, phone number: 1-800-35-NIOSH (1-800-356-4674)

The "Invisible" Killer (CPSC Document #464)

Prepared by the U.S. Consumer Product Safety Commission, this leaflet describes symptoms of carbon monoxide poisoning, sources of carbon monoxide in the home, and actions that can reduce the risk of carbon monoxide poisoning.  PDF version of this brochure -  [En Español]

Carbon Monoxide Fact Sheet (CPSC Document #466)

Discusses carbon monoxide (CO) hazards; and prevention and detection of dangerous CO levels. [En Español]

What You Should Know About Combustion Appliances and Indoor Air Pollution (CPSC Document #452)

This booklet answers some common questions you may have about the potential for one specific type of hazard - indoor air pollution - associated with one class of appliances - combustion appliances.

Responding to Residential Carbon Monoxide Incidents , July 23, 2002 (CPSC Publication)

Guidelines for first reponders to residential carbon monoxide incidents

Carbon Monoxide Poisoning From Camping Equipment (CPSC Document #5008)

Safety Alert: Discusses carbon monoxide (CO) poisoning and explains how C0 can cause CO poisoning from camping equipment such as portable camping heaters, lanterns, stoves inside tents, campers and vehicles. Provides steps to take to prevent such poisonings and how to recognize the symptoms of CO poisoning.

Carbon Monoxide Detectors Can Save Lives (CPSC Document #5010)

Safety Alert: Discusses how (CO) detectors can save your life describes the symptoms of CO poisoning.

Deaths From Burning Charcoal in Homes, Vehicles, and Tents (CPSC Document #5012)

Safety Alert: Discusses the hazards of carbon monoxide, which causes 25 deaths from carbon monoxide each year in these environments.

Other CPSC Indoor Air Quality Publications -