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Indoor Air

Carbon Monoxide (CO)

Carbon monoxide is an odorless, colorless and toxic gas. Because it is impossible to see, taste or smell the toxic fumes, CO can kill you before you are aware it is in your home. At lower levels of exposure, CO causes mild effects that are often mistaken for the flu. These symptoms include headaches, dizziness, disorientation, nausea and fatigue. The effects of CO exposure can vary greatly from person to person depending on age, overall health and the concentration and length of exposure.

Contents

Basic Information on Pollutants and Sources of Indoor Air Pollution

Sources of Carbon Monoxide

Unvented kerosene and gas space heaters; leaking chimneys and furnaces; back-drafting from furnaces, gas water heaters, wood stoves, and fireplaces; gas stoves; generators and other gasoline powered equipment; automobile exhaust from attached garages; and tobacco smoke. Incomplete oxidation during combustion in gas ranges and unvented gas or kerosene heaters may cause high concentrations of CO in indoor air. Worn or poorly adjusted and maintained combustion devices (e.g., boilers, furnaces) can be significant sources, or if the flue is improperly sized, blocked, disconnected, or is leaking. Auto, truck, or bus exhaust from attached garages, nearby roads, or parking areas can also be a source.

Health Effects Associated with Carbon Monoxide

Read "Care for Your Air: A Guide to Indoor Air Quality"

At low concentrations, fatigue in healthy people and chest pain in people with heart disease. At higher concentrations, impaired vision and coordination; headaches; dizziness; confusion; nausea. Can cause flu-like symptoms that clear up after leaving home. Fatal at very high concentrations. Acute effects are due to the formation of carboxyhemoglobin in the blood, which inhibits oxygen intake. At moderate concentrations, angina, impaired vision, and reduced brain function may result. At higher concentrations, CO exposure can be fatal.

Levels in Homes

Average levels in homes without gas stoves vary from 0.5 to 5 parts per million (ppm). Levels near properly adjusted gas stoves are often 5 to 15 ppm and those near poorly adjusted stoves may be 30 ppm or higher.

Steps to Reduce Exposure to Carbon Monoxide

It is most important to be sure combustion equipment is maintained and properly adjusted. Vehicular use should be carefully managed adjacent to buildings and in vocational programs. Additional ventilation can be used as a temporary measure when high levels of CO are expected for short periods of time.

ALERT: Put generators outside.

Never use a generator inside homes, garages, crawlspaces, sheds, or similar areas. Deadly levels of carbon monoxide can quickly build up in these areas and can linger for hours, even after the generator has shut off.

  • Keep gas appliances properly adjusted.
  • Consider purchasing a vented space heater when replacing an unvented one.
  • Use proper fuel in kerosene space heaters.
  • Install and use an exhaust fan vented to outdoors over gas stoves.
  • Open flues when fireplaces are in use.
  • Choose properly sized wood stoves that are certified to meet EPA emission standards. Make certain that doors on all wood stoves fit tightly.
  • Have a trained professional inspect, clean, and tune-up central heating system (furnaces, flues, and chimneys) annually. Repair any leaks promptly.
  • Do not idle the car inside garage.

Measurement Methods

Some relatively high-cost infrared radiation adsorption and electrochemical instruments do exist. Moderately priced real-time measuring devices are also available. A passive monitor is currently under development.

Exposure Limits

Occupational Safety and Health Guideline for Carbon Monoxide, see www.osha.gov/SLTC/healthguidelines/carbonmonoxide/recognition.html

OSHA Note: This guideline summarizes pertinent information about carbon monoxide for workers and employers as well as for physicians, industrial hygienists, and other occupational safety and health professionals who may need such information to conduct effective occupational safety and health programs. Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new information is available.

[OSHA PEL] The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for carbon monoxide is 50 parts per million (ppm) parts of air (55 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration [29 CFR Table Z-1].

[NIOSH REL] The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for carbon monoxide of 35 ppm (40 mg/m(3)) as an 8-hour TWA and 200 ppm (229 mg/m(3)) as a ceiling [NIOSH 1992]. The NIOSH limit is based on the risk of cardiovascular effects.

[ACGIH TLV] The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned carbon monoxide a threshold limit value (TLV) of 25 ppm (29 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 15]. The ACGIH limit is based on the risk of elevated carboxyhemoglobin levels [ACGIH 1991, p. 229].

Additional Resources

To report a dangerous product or a product-related injury, call the Consumer Product Safety Commission's (CPSC) hotline at (800) 638-2772 or CPSC teletypewriter at (800) 638-8270. Consumer can obtain recall information at CPSC's website - www.cpsc.gov Consumers can report product hazards to info@cpsc.gov

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EPA's Office of Air and Radiation page on Carbon Monoxide - www.epa.gov/airquality/carbonmonoxide/

EPA's Office of Aging: Fact sheet: "Preventing Carbon Monoxide Poisoning Information for Older Adults and Their Caregivers" (PDF) (4 pp., 381 K) January 2009.

EPA's Office of Research and Development:

Centers for Disease Control and Prevention (CDC), National Center for Environmental Health - www.cpsc.gov

U.S. Consumer Product Safety Commission (CPSC): CPSC protects the public from the unreasonable risk of injury or death from 15,000 types of consumer products under the agency's jurisdiction. To report a dangerous product or a product-related injury, you can go to CPSC's forms page - www.cpsc.gov/talk.html and use the first on-line form on that page. Or, you can call CPSC's hotline at (800) 638-2772 or CPSC's teletypewriter at (800) 638-8270, or send the information to info@cpsc.gov.

U.S. Department of Homeland Security, U.S. Fire Administration, 16825 S. Seton Ave., Emmitsburg, MD 21727, Voice: (301) 447-1000 Fax: (301) 447-1346 Admissions Fax: (301) 447-1441,www.usfa.fema.gov

U.S. Coast Guard

Boating Safety Carbon Monoxide Warning

www.uscgboating.org/alerts exiting EPA

American Lung Association www.lungusa.org exiting EPA

Occupational Safety and Health Administration www.osha.gov

U.S. National Library of Medicine and the National Institute of Health - "Carbon Monoxide Poisoning" www.nlm.nih.gov/medlineplus/carbonmonoxidepoisoning.html

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About Carbon Monoxide Detectors

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Portable Generators

  • Consumer Product Safety Commission (CPSC): Portable generators are useful when temporary or remote electric power is needed, but they also can be hazardous. The primary hazards to avoid when using a generator are carbon monoxide (CO) poisoning from the toxic engine exhaust, electric shock or electrocution, and fire - www.cpsc.gov/cpscpub/pubs/portgen.html
  • Department of Homeland Security, U.S. Fire Administration's Portable Generator Hazards page - www.usfa.fema.gov/safety/co/generator.shtm
  • Surviving the Aftermath of Hurricane Katrina CPSC Warns of Deadly Post-Storm Dangers with Portable Generators, Candles and Wet Appliances, U.S. Consumer Product Safety Commission, Office of Information and Public Affairs, Washington, DC, August 31, 2005, Release #05-251 - www.cpsc.gov/CPSCPUB/PREREL/prhtml05/05251.html General CPSC publications list related to Home Heating Equipment - www.cpsc.gov/cpscpub/pubs/heatpubs.html
  • 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 - www.cdc.gov/niosh/cofact1.html

    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), e-mail: pubstaft@niosdt1.em.cdc.gov

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EPA Publications

Protect Your Familiy and Yourself from Carbon Monoxide Poisoning

Protect Your Family and Yourself from Carbon Monoxide Poisoning: 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. The Carbon Monoxide fact sheet has also been translated into Vietnamese EPA 402-F-99-004C, Chinese EPA 402-F-99-004A, and Korean EPA 402-F-99-004B

  • PDF Version (2 pp., 65 K)
  • EPA-402-F-96-005, October 1996

Proteja su vida y la de su familia: Evite el envenenamiento con monóxido de carbono

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Consumer Product Safety Commission Publications/Documents

Link to CPSC Indoor Air Quality Publications - www.cpsc.gov/cpscpub/pubs/iaq.html

  • 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 - www.cpsc.gov/cpscpub/pubs/464.pdf [En Español]
  • Carbon Monoxide Fact Sheet (CPSC Document #466) Discusses carbon monoxide (CO) hazards; and prevention and detection of dangerous CO levels - www.cpsc.gov/cpscpub/pubs/466.html [En Español]
  • Responding to Residential Carbon Monoxide Incidents , July 23, 2002 (CPSC Publication) Guidelines for first responders to residential carbon monoxide incidents - www.cpsc.gov/library/foia/foia04/os/resident.pdf
  • 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 - www.cpsc.gov/cpscpub/pubs/5008.html
  • 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 - www.cpsc.gov/cpscpub/pubs/5010.html
  • 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 - www.cpsc.gov/cpscpub/pubs/5012.html

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