Category: Health & Safety

Understanding Carbon Monoxide Safety

Carbon monoxide, commonly called CO, is a poisonous gas that cannot be seen, smelled, or tasted. A person may breathe dangerous levels without realizing anything is wrong.

Carbon monoxide is produced when fuels do not burn completely. It can build up when a furnace, generator, vehicle, fireplace, grill, stove, water heater, or other fuel-burning device is used incorrectly, damaged, poorly maintained, or inadequately vented.

CO poisoning can cause headache, dizziness, nausea, confusion, unconsciousness, permanent injury, or death. A working carbon monoxide alarm provides an important warning, but alarms must be installed, tested, and replaced correctly.

If a carbon monoxide alarm sounds, get everyone—including pets—outside immediately and call 911 from a safe location.

Where Carbon Monoxide Comes From

Many common devices can produce carbon monoxide, including:

• Gas or oil furnaces
• Gas water heaters
• Boilers
• Fireplaces
• Woodstoves
• Gas ranges and ovens
• Portable generators
• Charcoal grills
• Gas grills
• Camp stoves
• Fuel-burning space heaters
• Gasoline-powered tools
• Pressure washers
• Lawn equipment
• Cars and trucks
• Motorcycles
• Boats
• Recreational vehicles
• Propane appliances
• Kerosene heaters

Properly installed and maintained equipment should direct exhaust safely outside. Problems develop when a device malfunctions, a vent becomes blocked, equipment is used in an enclosed space, or exhaust enters through a nearby door, window, or vent.

Why Carbon Monoxide Is So Dangerous

Carbon monoxide enters the bloodstream through the lungs and interferes with the blood’s ability to carry oxygen.

The brain, heart, and other organs can be injured when they do not receive enough oxygen. A person may become confused or weak before realizing they need to leave.

CO exposure can happen:

• Suddenly at a high level
• Gradually over several hours
• Repeatedly at lower levels
• During sleep
• During a power outage
• While traveling in a vehicle or boat
• In more than one person at the same time

The CDC describes carbon monoxide as an odorless, colorless gas that can cause sudden illness and death. CDC carbon-monoxide overview

Signs of Carbon Monoxide Poisoning

Common symptoms include:

• Headache
• Dizziness
• Weakness
• Fatigue
• Nausea
• Vomiting
• Chest pain
• Shortness of breath
• Confusion
• Difficulty concentrating
• Poor coordination
• Blurred vision
• Unusual sleepiness
• Fainting
• Seizure
• Loss of consciousness

Symptoms are sometimes described as “flu-like,” but CO poisoning usually does not cause a fever.

Important warning patterns include:

• Several people developing similar symptoms
• Symptoms improving after leaving the building
• Symptoms returning after going back inside
• A pet becoming weak, ill, or unusually sleepy
• Symptoms appearing while a heater, fireplace, generator, or vehicle is operating
• An alarm sounding even though no smoke or fire is visible

Do not wait for everyone to develop symptoms. One person may be affected before another.

Who Is at Greater Risk?

Everyone can be poisoned by carbon monoxide, but certain people may become seriously ill sooner, including:

• Infants
• Children
• Older adults
• Pregnant people
• Unborn babies
• People with heart disease
• People with anemia
• People with lung or breathing conditions
• People who are sleeping
• People who have consumed alcohol
• People taking medication that causes sedation

A sleeping or intoxicated person may not notice symptoms or hear an alarm in time to escape.

What to Do When a CO Alarm Sounds

Treat every carbon monoxide alarm as a real emergency.

1. Leave immediately

Get everyone outside, including children, older adults, people with disabilities, and pets.

Do not stop to:

• Search for the source
• Open every window
• Turn off appliances
• Collect belongings
• Reset the alarm
• Call from inside
• Wait to see whether the alarm stops

2. Call 911 from outside

Tell the dispatcher:

• That a carbon monoxide alarm is sounding
• Whether anyone has symptoms
• How many people and pets were inside
• Whether a generator, furnace, fireplace, vehicle, or other fuel-burning device was operating
• Whether anyone remains inside

3. Do not reenter

Stay outside until firefighters or other qualified professionals confirm that the building is safe.

Opening doors and windows does not prove the source has been corrected. Carbon monoxide may build up again after the home is closed.

Current CPSC guidance says never to ignore a CO alarm: get outside immediately and then call 911. CPSC carbon-monoxide safety guidance

If Someone Has Symptoms

Move the person to fresh air only when you can do so without exposing yourself.

Call 911 immediately if someone has:

• Confusion
• Chest pain
• Significant breathing difficulty
• Fainting
• A seizure
• Severe weakness
• Inability to walk normally
• Loss of consciousness
• Abnormal breathing

If the person is not breathing normally:

1. Call 911.
2. Begin CPR.
3. Use an AED if available.
4. Continue until the person begins breathing normally or emergency responders take over.

Do not enter a contaminated building to rescue someone without proper protective equipment. Firefighters can enter with breathing protection. Tell 911 that someone may still be inside.

Anyone with possible CO poisoning should receive medical guidance even if symptoms improve in fresh air. The person may need blood testing, oxygen, heart monitoring, or additional treatment.

Do not drive yourself to the hospital if you are dizzy, confused, weak, or otherwise impaired.

Carbon Monoxide Alarms Save Lives

Because people cannot detect CO with their senses, alarms are essential.

The Consumer Product Safety Commission recommends installing carbon monoxide alarms:

• On every level of the home
• Outside each separate sleeping area
• According to the manufacturer’s instructions

Alarms should be battery-operated or have battery backup so they continue working during a power outage. Interconnected alarms provide additional protection because when one sounds, they all sound. CPSC CO-alarm guidance

Helpful Resources: Browse Smoke & Carbon Monoxide Alarms for products, equipment, services, or supplies related to this section.

Where to Install CO Alarms

Install alarms in locations recommended by the manufacturer and required by local code.

Important areas generally include:

• Hallways outside bedrooms
• Every occupied level
• Areas near sleeping spaces
• Basements when used as living or sleeping space
• Locations where the alarm can be heard

Do not guess about wall or ceiling placement. Different alarms have different installation requirements.

Avoid placing an alarm:

• Directly beside a fuel-burning appliance
• In a bathroom
• In direct sunlight
• Near a heating or cooling vent
• Behind furniture or curtains
• In an unusually dusty or humid area
• Where children can tamper with it
• In a location outside its rated temperature range

An alarm placed too close to an appliance may experience nuisance activations. One placed too far away or in a dead-air area may not provide timely warning.

Follow the exact spacing and placement instructions included with the alarm.

Smoke Alarms and CO Alarms Are Not the Same

A smoke alarm detects products of a fire. A carbon monoxide alarm detects dangerous CO levels.

A home needs both protections.

Options include:

• Separate smoke and CO alarms
• Combination smoke-and-CO alarms

Combination models should meet the applicable safety standards for both smoke and carbon monoxide detection.

The alarm sounds may differ. Learn the smoke, CO, low-battery, and end-of-life signals before an emergency.

Do not assume that a smoke alarm also detects carbon monoxide unless its labeling specifically says so.

Choose a Reliable Alarm

Look for a CO alarm that:

• Is listed by a recognized testing laboratory
• Meets current safety standards
• Is appropriate for the home and installation location
• Has battery backup when plug-in or hardwired
• Provides accessible alerts for household members who need them
• Has not been recalled

Current CPSC guidance recommends purchasing CO alarms that comply with UL 2034. Combination alarms should also comply with the current smoke-alarm standard. Check the model against the CPSC recall and warning database.

Be cautious with very inexpensive, unfamiliar products from third-party online sellers. Some detectors have been found unable to sound during testing.

Test CO Alarms Monthly

Use the test button at least once each month.

During the test:

1. Warn household members.
2. Press and hold the button according to the instructions.
3. Confirm that the alarm sounds.
4. Check interconnected alarms.
5. Confirm that everyone can hear or otherwise detect the signal.
6. Replace the battery or unit if it fails.
7. Record the test date.

The test button checks the electronic alarm circuit. It does not create carbon monoxide or prove that every part of the sensor is functioning perfectly.

Never test a CO alarm with:

• Vehicle exhaust
• A grill
• A lighter
• A stove
• A candle
• Smoke
• Any combustion source

Creating carbon monoxide for testing can poison someone.

Replace Batteries and Alarms as Directed

CO alarms may use:

• Replaceable batteries
• Sealed long-life batteries
• Plug-in power with battery backup
• Hardwired power with battery backup

Replace removable batteries according to the manufacturer’s directions and whenever a low-battery signal occurs.

Do not remove the battery because the alarm chirps. The chirp may indicate:

• Low battery
• Malfunction
• End of service life
• Another condition requiring attention

Carbon monoxide sensors do not last forever. The replacement period varies by model and may be approximately five to ten years.

Check:

• The manufacture date
• The replacement date
• The product instructions
• The end-of-life signal

Replace the entire unit when required. A new battery cannot restore an expired sensor.

Helpful Resources: Browse Safety Equipment Organization & Maintenance for products, equipment, services, or supplies related to this section.

Make Alarms Accessible

A standard audible alarm may not adequately protect someone who:

• Is deaf or hard of hearing
• Sleeps deeply
• Takes sedating medication
• Has difficulty recognizing alarms
• Has an intellectual or developmental disability
• Sleeps far from the device

Available supports may include:

• Strobe lights
• Bed or pillow shakers
• Low-frequency sound
• Voice alerts
• Interconnected systems
• Monitored alarm services

Phone notifications may provide an additional warning but should not replace properly installed alarms.

Test the system when household members are in their usual sleeping locations.

Prevent Carbon Monoxide From Heating Equipment

Have fuel-burning heating equipment inspected and serviced by a qualified professional according to the manufacturer’s recommendations, generally before the heating season.

Equipment may include:

• Furnaces
• Boilers
• Fireplaces
• Woodstoves
• Gas water heaters
• Gas space heaters
• Oil-burning equipment

A professional should check:

• Venting
• Chimneys
• Flues
• Connections
• Combustion
• Safety controls
• Signs of leaks or damage

Do not attempt repairs involving gas, oil, combustion, or venting unless you are qualified.

Keep Vents, Chimneys, and Flues Clear

Blocked exhaust can force carbon monoxide back into the home.

Possible blockages include:

• Snow
• Ice
• Leaves
• Animal nests
• Debris
• Collapsed chimney material
• Improper construction
• Stored objects
• Home-renovation materials

After a major storm:

• Check exterior vents from a safe location.
• Remove snow from around appliance exhausts.
• Arrange professional inspection if damage is possible.
• Do not climb onto an icy roof.
• Do not operate an appliance with a damaged or blocked vent.

Have chimneys inspected and cleaned regularly.

Never Heat a Home With a Gas Oven

A gas range or oven is designed for cooking, not space heating.

Using it to heat a home can:

• Produce carbon monoxide
• Deplete oxygen
• Cause burns
• Start a fire
• Damage the appliance

Do not sleep in a room heated by an unvented cooking appliance.

If the home is dangerously cold:

• Go to a warming center.
• Stay with family or friends.
• Contact local emergency services.
• Use only heating equipment approved for indoor use and follow all instructions.

Portable Generator Safety

Generators are a major source of preventable carbon monoxide deaths during power outages.

Never operate a portable generator inside:

• A house
• A garage
• A basement
• A crawlspace
• A shed
• A carport
• A porch
• A tent
• An enclosed or partially enclosed area

Opening doors or windows does not make indoor generator use safe.

Operate the generator:

• Outdoors
• More than 20 feet from the building
• Away from doors, windows, and vents
• With the exhaust directed away from structures
• According to the manufacturer’s instructions
• With protection from weather that does not trap exhaust
• With a battery-powered or battery-backup CO alarm operating inside

The CDC specifically recommends placing generators outdoors more than 20 feet from windows, doors, and vents. CDC generator and carbon-monoxide guidance

A carbon-monoxide shutoff feature adds protection but does not make it safe to use a generator indoors or near a building opening.

Grills, Camp Stoves, and Charcoal

Never use a charcoal grill, gas grill, camp stove, lantern, or similar fuel-burning device inside:

• A house
• A garage
• A tent
• A camper not designed for that appliance
• A shed
• A basement
• A vehicle
• Another enclosed or partially enclosed space

Charcoal continues producing carbon monoxide even when it appears gray or the flames are gone.

Do not bring a grill indoors for heat after cooking.

Use only equipment specifically approved for the location and follow ventilation requirements exactly.

Vehicle Safety

Vehicle exhaust contains carbon monoxide.

Never run a car or truck inside an attached garage, even when the garage door is open.

Additional precautions include:

• Move the vehicle outside before warming it.
• Do not use remote start while the vehicle is inside a garage.
• Check that the garage door is fully open before moving a vehicle.
• Turn the engine off immediately after parking.
• Never sleep in a running vehicle in an enclosed area.
• Have exhaust systems inspected.
• Repair exhaust leaks promptly.
• Clear snow from the tailpipe before starting the vehicle.
• Do not idle near open windows, doors, or building vents.

An attached garage can allow exhaust to enter living spaces. Close the door between the home and garage and ensure it seals correctly, but do not rely on that door as protection while a vehicle is running.

Tailgates and Exhaust

Driving with a rear hatch or tailgate open can pull exhaust into a vehicle.

If a tailgate must remain open:

• Open other windows or vents to increase airflow.
• Minimize the distance traveled.
• Do not allow passengers to remain near the exhaust area.
• Follow the vehicle manufacturer’s instructions.
• Stop immediately if anyone develops headache, dizziness, nausea, or unusual sleepiness.

Never transport someone in a cargo area not designed for passengers.

Boats and Recreational Vehicles

Boats and RVs may contain:

• Engines
• Generators
• Fuel-burning appliances
• Enclosed sleeping areas

Carbon monoxide can collect in cabins, beneath canopies, near rear decks, and around other boats’ exhaust.

To reduce risk:

• Install appropriate marine or RV carbon-monoxide alarms.
• Maintain engines and exhaust systems.
• Do not block vents.
• Keep swimmers away from exhaust outlets.
• Do not sleep near a running generator.
• Avoid remaining beside another boat’s running engine or generator.
• Follow all manufacturer and Coast Guard guidance.

The CDC recommends keeping people away from boat exhaust areas and obtaining fresh air and emergency help immediately when poisoning is suspected. CDC boating CO guidance

Workplaces, Garages, and Workshops

Gasoline-powered equipment should not be operated inside enclosed work areas.

Possible sources include:

• Pressure washers
• Concrete saws
• Floor buffers
• Pumps
• Compressors
• Welding equipment
• Forklifts
• Small engines

Opening a garage door or window may not provide adequate ventilation.

Use electric, battery-powered, or compressed-air equipment when appropriate. Place engines outside and away from building openings.

If workers develop headaches, nausea, dizziness, or confusion, stop work, move to fresh air, and call emergency services.

Do Pets Show Symptoms?

Pets can also be poisoned by carbon monoxide.

Warning signs may include:

• Weakness
• Vomiting
• Unusual sleepiness
• Difficulty breathing
• Confusion
• Collapse
• Seizure

A pet may show symptoms before people do.

If CO exposure is possible:

• Get the pet outside.
• Call 911 for the household emergency.
• Contact a veterinarian or emergency veterinary hospital.
• Do not reenter the building.

What a Digital CO Reading Means

Some alarms display a carbon-monoxide level or store a peak reading.

These features can provide useful information, but:

• Not every displayed number triggers an alarm.
• Low readings can have different causes.
• Alarm thresholds and timing are determined by the device’s design and safety standard.
• A zero display does not prove that every room is safe.
• A household alarm is not a substitute for professional air monitoring.

Do not remain inside while watching the display rise. If the full alarm sounds or anyone has symptoms, leave immediately and call 911.

Contact the manufacturer, fire department, utility, or qualified technician when the device repeatedly displays unusual readings or activates.

If an Alarm Chirps but Does Not Fully Sound

A periodic chirp may indicate:

• Low battery
• End of sensor life
• Malfunction
• Power interruption
• Improper installation

Read the alarm’s instructions and identify the signal.

Do not simply remove the battery.

If you cannot determine what the sound means:

• Move to fresh air if there is any possibility of danger.
• Call the fire department’s nonemergency number or the manufacturer from outside.
• Replace an expired or malfunctioning alarm.
• Check for recalls.

If anyone has symptoms, call 911.

If an Alarm Activates Repeatedly

Repeated activation should be investigated.

Possible causes include:

• Malfunctioning furnace
• Blocked vent
• Damaged chimney
• Generator exhaust
• Vehicle exhaust
• Gas water heater problem
• Improperly vented fireplace
• Neighboring equipment
• Defective or expired alarm

Do not assume the alarm is overly sensitive. Have the home evaluated by the fire department, utility company, or qualified appliance technician.

Do not move the alarm to a distant area or disable it to silence repeated warnings.

Carbon Monoxide Safety for Renters

Renters should:

• Test alarms when moving in.
• Learn which alarms detect smoke, CO, or both.
• Check manufacture and replacement dates.
• Report missing or malfunctioning alarms in writing.
• Keep copies of maintenance requests.
• Ask who replaces batteries.
• Never disable an alarm.
• Know where fuel-burning equipment is located.
• Report unusual odors, soot, venting problems, or repeated headaches.

Carbon monoxide itself has no odor. An unusual fuel, exhaust, or burning smell may indicate another problem that requires attention.

If the landlord does not address a serious hazard, contact the local fire department, building department, housing authority, utility company, or tenant-support service.

Leave and call 911 if an alarm sounds or poisoning is suspected.

After a Storm, Flood, or Power Outage

Carbon monoxide risk increases when people use alternative power and heat.

During an outage:

• Use generators outdoors and more than 20 feet away.
• Never use grills or camp stoves indoors.
• Never heat the home with an oven.
• Use battery-powered lights instead of fuel-burning lanterns when possible.
• Keep appliance vents clear of snow and debris.
• Make sure CO alarms have battery backup.
• Go to a safe shelter if the home cannot be heated safely.

After flooding:

• Do not use fuel-burning equipment that was submerged.
• Have furnaces, water heaters, wiring, and controls inspected.
• Do not assume an appliance is safe because it turns on.

Prevention for Older Adults and People With Disabilities

Create a plan that accounts for:

• Hearing loss
• Limited mobility
• Wheelchair or walker use
• Memory impairment
• Sedating medications
• Oxygen equipment
• Difficulty calling for help
• Need for assistance with stairs

Consider interconnected alarms, visual alerts, bed shakers, monitored systems, and an emergency contact plan.

Keep mobility aids, shoes, a phone, and necessary medical equipment close to the sleeping area. Practice leaving the home safely.

Common Mistakes to Avoid

To prevent carbon monoxide poisoning:

• Do not rely on smell.
• Do not ignore headaches affecting several household members.
• Do not wait for severe symptoms.
• Do not disable a CO alarm.
• Do not ignore repeated alarms.
• Do not run a generator in a garage, shed, porch, or carport.
• Do not place a generator near doors, windows, or vents.
• Do not use a gas oven for heat.
• Do not burn charcoal indoors.
• Do not warm a vehicle inside an attached garage.
• Do not assume an open garage door provides enough ventilation.
• Do not block appliance exhaust vents.
• Do not use damaged or flooded fuel-burning equipment.
• Do not reenter after an alarm until professionals say it is safe.
• Do not rely on a smoke alarm to detect carbon monoxide.

A Simple Carbon Monoxide Safety Checklist

1. Install CO alarms on every level.
2. Install alarms outside each sleeping area.
3. Use alarms with battery backup.
4. Test alarms monthly.
5. Replace batteries and alarms as directed.
6. Learn the alarm signals.
7. Service fuel-burning equipment regularly.
8. Keep chimneys and vents clear.
9. Never heat the home with a gas oven.
10. Operate generators outdoors, more than 20 feet from openings.
11. Never use charcoal or outdoor cooking equipment indoors.
12. Never idle a vehicle in an attached garage.
13. Leave immediately when an alarm sounds.
14. Call 911 from outside.
15. Do not return until professionals approve reentry.

Carbon monoxide cannot be detected by human senses. Prevention depends on safe equipment use, regular maintenance, working alarms, and an immediate response whenever an alarm sounds.

Suggested Guides

• Understanding Smoke Alarms & Fire Extinguishers
• Preventing Burns & Electrical Injuries
• What to Do When Someone Is Unconscious
• Understanding CPR & How to Use an AED
• Responding to Serious Difficulty Breathing or an Asthma Attack
• Creating an Emergency Plan for Aging at Home

Important Health & Safety Notice

The information in this guide is provided for general educational purposes only. Independence Answers is not a medical provider, and this content is not a substitute for professional medical advice, diagnosis, treatment, or supervision. Always follow the instructions of your doctor, pharmacist, or other qualified healthcare professional, especially if you have a medical condition, take medication, or are unsure whether an action is safe for you.

Do not ignore or delay seeking professional care because of something you read here. If you believe someone may be experiencing a serious or life-threatening emergency, call 911 or your local emergency number immediately.