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Carbon Monoxide Questions & Answers

Provided by the Oregon State Fire Marshall, updated June 2010. View this information as a printable PDF. Find other resources for home buyers and sellers.

What is carbon monoxide?

  1. It is an invisible, odorless, colorless gas created when fuels, such as gasoline, wood, charcoal, coal, natural gas, propane, oil, kerosene and methane burn incompletely

Where does carbon monoxide come from?

  1. Heaters, fireplaces, furnaces, appliances and cooking sources using coal, wood, heating oil (like Romeo’s Fuel) petroleum products, and other fuels producing carbon monoxide

  2. Products and equipment powered by an internal combustion engine, such as portable generators, cars, lawn mowers, and power washers produce carbon monoxide

  3. Operating equipment inside an attached garage increases the risk of introduction of carbon monoxide into a living space

What are the risk factors of carbon monoxide?

  1. Carbon monoxide fumes are dangerous and may be deadly. Especially at risk are:

  2. Unborn babies

  3. Infants

  4. Older adults

  5. People who smoke

  6. People with chronic heart disease, anemia or respiratory problems

Why should my home have carbon monoxide alarms?

  1. According to the Journal of the American Medical Association, approximately 2,100 people die from carbon monoxide poisoning every year in the United States

  2. There are more than 10,000 injuries annually from carbon monoxide

  3. Fuel burning home heating and cooking equipment are sources of carbon monoxide

  4. Car exhaust in an attached garage may leak carbon monoxide into the house even with the main garage door open

Why is carbon monoxide harmful?

  1. It displaces oxygen in the blood and deprives the heart, brain, and other vital organs of oxygen

  2. The molecules attach to your red blood cells more easily than oxygen molecules, depriving oxygen from getting into the body. This may damage tissues and result in death

What are symptoms of carbon monoxide poisoning?

  1. Initial symptoms are similar to the flu but without the fever:

  2. Headache

  3. Fatigue

  4. Shortness of breath

  5. Nausea

  6. Dizziness

  7. Skin may turn bright red

  8. Severe symptoms include:

  9. Mental confusion

  10. Vomiting

  11. Loss of muscular coordination

  12. Loss of consciousness

  13. Ultimately death

Who does what, when?

  1. Oregon law requires carbon monoxide alarms to be installed following specific House Bill 3450 implementation dates:

  2. JULY 1, 2010 – Office of State Fire Marshal (OSFM) Administrative Rules effective date

  3. JULY 1, 2010 – For all new rental agreements, landlords must provide properly functioning carbon monoxide alarms for rental dwelling units with, or within a structure containing, a carbon monoxide source

  4. APRIL 1, 2011 – Landlords must provide properly functioning carbon monoxide alarms for all rental dwelling units with, or within a structure containing a carbon monoxide source

  5. APRIL 1, 2011 – Home sellers of one-and two family dwellings, manufactured dwellings, or multifamily housing units containing a carbon monoxide source must have one or more properly functioning carbon monoxide alarms before conveying fee title or transferring possession of a dwelling

  6. APRIL 1, 2011 – Carbon monoxide alarms are required in new construction or a structure that undergoes reconstruction, alteration or repair for which a building permit is required, and is identified in the structural specialty code as a residential Group R structure.(for new construction and reconstruction go to Oregon Buildings Codes

What is a carbon monoxide alarm?

  1. Detects carbon monoxide

  2. Produces a distinctive audible alert when carbon monoxide is detected

  3. Must comply with ANSI/UL 2034 or 2075 or other nationally recognized testing laboratory

  4. May be a separate stand alone unit or part of a detection and alarm system

What types of carbon monoxide alarms are available?

1. Carbon monoxide only alarms: Activated by carbon monoxide

  1. May be battery-operated, plug-in, or hard-wired

  2. Battery back-up is recommended for plug-in and hardwired alarms

2. Combination smoke/carbon monoxide alarms: Activated by smoke or carbon monoxide

  1. Combination smoke/carbon monoxide alarms must comply with ANSI/UL 217 and ANSI/UL 2034

  2. Combination smoke/carbon monoxide detectors must comply with ANSI/UL 268 and ANSI/UL 2075

3. Ionization smoke/carbon monoxide alarms: Activated by smoke or carbon monoxide These alarms are labeled on either the front or back of the alarm with:

  1. ‘Smoke and carbon monoxide alarm’

  2. A lower case letter ‘i’ for ionization and the word ‘ionization’

  3. The phrase ‘contains radioactive material’

  4. NOTE: These alarms do not require a 10-year battery

4. Photoelectric smoke/carbon monoxide alarm: Activated by smoke or carbon monoxide. These alarms are labeled on either the front or back of the alarm with:

  1. ‘smoke and carbon monoxide alarm’

  2. a capital letter ‘P’ for photoelectric and the word ‘photoelectric’

5. Photoelectric smoke/carbon monoxide with voice alarm: Activated by smoke or carbon monoxide. An audible voice tone speaks the type and location of danger in your home, when programmed. These alarms are labeled on either the front or back of the alarm with:

  1. A capital letter ‘P’ and the word ‘photoelectric’

  2. ‘Smoke and carbon monoxide alarm’

6. Explosive gas & carbon monoxide alarm: Activated by carbon monoxide, propane or natural/methane gas. These alarms are labeled on either the front or back of the alarm with:

  1. ‘Explosive gas and carbon monoxide alarm’ on the front of the alarm

7. Plug-In Alarms: Plug-in alarms are simple to use and provide dependable protection for your family. The installation of this type of CO gas detector is as simple as plugging it into a standard electrical socket in your home. This plug-in CO alarm has a battery backup that ensures CO protection even if your house loses power.

  1. Detects both carbon monoxide and explosive gases.

  2. Has a backlit digital display for easy reading.

Visit if you’re curious about propane cylinders for portable propane appliances.

What is the difference between ionized and photoelectric?

  1. Ionization smoke detectors feature a radioactive source within a dual detection chamber. Ionization alarms sense an unseen change in the electrical conductivity

  2. Ionization detectors sense smoke invisible to the human eye

  3. Photoelectric detectors respond to visible by-products of combustion – When enough visible combustibles are present, the detector sounds an alarm

May I modify my hard-wired smoke alarm system for a combination carbon monoxide and smoke alarm?

  1. You may swap a hardwired smoke alarm for a hardwired smoke/carbon monoxide combination unit when replacement combination alarms are from the same manufacturer

  2. Switching from one manufacturer’s unit to another requires a power adapter plug

  3. Manufacturers advise adapter plugs may be changed using wire nuts and may require a qualified electrician

Where do I install carbon monoxide alarms?

  1. On each level of your home with sleeping areas

  2. In each bedroom or within 15 feet outside each sleeping area

  3. Install alarms according to the manufacturer’s instructions

Do the current temporary rules require a carbon monoxide alarm in each sleeping area?

  1. No, but it is still a recommended best practice to have them in both the bedroom and within 15 feet outside the bedroom

  2. The law requires a carbon monoxide alarm on each level of your home with sleeping areas and within 15 feet of each sleeping area. However, ductwork from sources often goes directly to bedrooms, bypassing hallways outside of sleeping areas

Where should carbon monoxide alarms NOT be installed?

  1. Garages and kitchens

  2. Extremely dusty, dirty, humid, or greasy areas

  3. Direct sunlight or areas prone to temperature extremes. These include unconditioned crawl spaces such as ventilated attics, basement, and crawl spaces, unfinished attics, uninsulated or poorly insulated ceilings, and porches

  4. In electrical outlets covered by curtains or other obstructions

  5. In turbulent air such as near ceiling fans, heat vents, air conditioners, fresh air returns, or open windows. Blowing air may prevent carbon monoxide from reaching the sensors

  6. Directly above or beside fuel-burning appliances, as appliances may emit a trace amount of carbon monoxide only upon start-up

  7. Within 15 feet of heating and cooking appliances, or in or near, very humid areas such as bathrooms

How often do I replace my carbon monoxide alarm?

  1. Most carbon monoxide alarms have a five year limited warranty

  2. Manufacturers recommend replacing alarms five years from date of production

How do I keep my carbon monoxide alarm working?

  1. Test alarms monthly

  2. Vacuum alarms regularly to remove dust and cobwebs

  3. Never disconnect or remove alarm batteries for other use

  4. For battery operated, replace the 9-volt or AA batteries at least once per year

  5. Carbon monoxide alarms are not required to have a 10-year battery

  6. Carbon monoxide/smoke combination alarms are not required to have a 10-year battery

What should I do when the carbon monoxide alarm sounds?

  1. Don’t ignore the alarm! It is intended to warn household members before they experience symptoms

  2. Silence the alarm

  3. Move everyone outside to fresh air and call for help from a fresh air location:

  4. If anyone is experiencing symptoms of carbon monoxide poisoning, call 9-1-1

  5. If no one has symptoms, ventilate the building and contact a qualified service technician

  6. Have all home equipment powered by fuels such as gas, wood, coal, natural gas, propane, oil, or methane inspected by a qualified technician

  7. Have fuel-burning heating equipment and chimneys inspected by a professional every year before cold weather sets in

For more information on Oregon’s carbon monoxide law, visit: or call 503-934-8228

Additional references:

CARBON MONOXIDE in Oregon Statutes at

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