Treat every fuel-burning appliance and attached garage as a CO source. Install UL-listed CO alarms on every level and outside sleeping areas; mount them on wall or ceiling, 5–20 feet from appliances, then test monthly, change batteries yearly, and replace units at 10 years. Keep chimneys and vents clear of snow and debris, run exhaust fans and provide make-up air, and schedule annual licensed inspections. If an alarm sounds, evacuate and call 911. More steps follow.
Carbon Monoxide Checklist: Do These 10 Things
Where can carbon monoxide (CO) build up in your home? It accumulates near fuel-burning appliances, chimneys, and attached garages when combustion exhaust can’t vent. Keep vents and chimneys unobstructed; clear debris, snow, and ice, and recheck after storms. Run listed exhaust fans whenever you operate fuel-burning appliances, and open windows periodically to restore make-up air. Seal the wall and penetrations between the house and attached garage, and keep the door to the garage closed.
Because CO is colourless, odourless and tasteless, detectors are essential for early warning.
Schedule annual inspections of all fuel-burning appliances by licensed contractors. Confirm steady blue flames and proper draft; correct yellow flames, soot, corrosion, cracks, leaks, or blocked vents. Inspect gas connections and vent pipes for damage. Clean fireplaces and chimneys yearly by certified professionals. Never use generators, grills, or camping heaters indoors, or within 20 feet of openings. Don’t idle vehicles or run gas tools in garages. Never heat with ovens or dryers. Track inspection dates.
Install, Test, and Replace CO Detectors Correctly
Good venting and safe appliance operation reduce CO risk, but you still need properly installed and maintained CO detectors to alert you if exhaust backs up or combustion goes incomplete. In larger floor plans—like two- and three-bedroom units with gas appliances—consider installing two CO alarms to better cover separated sleeping areas. Install UL-listed CO alarms on every level, including the basement, and place one outside each sleeping area, ideally within 10 feet of bedroom doors. Mount on a wall or ceiling per the booklet; height isn’t critical because CO mixes with air. Keep units out of dead-air corners and away from windows, doors, and obstructions. Locate alarms 5–20 feet from fuel-burning appliances (or at least 15 feet where required by the manufacturer) and never install them in garages. Follow the manufacturer’s instructions for battery, plug-in with backup, hard-wired with backup, or wireless models, and use separate smoke alarms too. Test as directed; test battery units weekly using the test button. Replace batteries yearly and immediately on low-power chirps. Replace the entire alarm at 10 years or sooner if dated.
Prevent Carbon Monoxide From Appliances and Garages
Even if your appliances seem to run fine, you can still get dangerous carbon monoxide (CO) when combustion air is restricted, vents backdraft, or engine exhaust migrates from an attached garage. Schedule annual, licensed inspections of your furnace, water heater, and other fuel-burning equipment to confirm safe draft, tight vent joints, and proper burner adjustment. Keep chimneys and vent terminations clear; don’t tarp or cap them during renovations, and verify nothing new blocks required combustion air openings. Don’t line oven bottoms with aluminum foil, and never use ranges, ovens, or clothes dryers as space heaters. Prohibit unvented fuel-burning appliances in sleeping areas, and don’t run charcoal grills or gasoline engines indoors. In garages, keep vehicles off and avoid idling; even with the door open, exhaust can infiltrate living spaces. Run portable generators only outdoors, at least 25 feet away, downwind, and away from windows, doors, and vents. Install carbon monoxide detectors on every level of the home to provide early warning if CO builds up.
What to Do Immediately If a CO Alarm Sounds
When a carbon monoxide alarm sounds, treat it as an emergency and evacuate to fresh air immediately. Alert everyone as you exit, move calmly and quickly to the nearest safe exit, and assist children, older adults, and mobility-impaired occupants. Don’t stop for belongings, and don’t enter enclosed spaces such as garages. Close doors behind you to help confine the condition, but don’t lock them, and proceed to your primary assembly point for a headcount.
Once outside, call 911. Report the alarm activation, your address, any symptoms (headache, dizziness, nausea, chest pain), and how many people and pets evacuated. Request a response with a calibrated CO meter and inspection. Don’t ventilate the building before leaving and don’t re-enter, even if the alarm stops, until first responders clear it. If anyone is ill or unconscious, keep them in fresh air and don’t let them drive; wait for EMS.
Remember that carbon monoxide is a colorless, odorless gas, so you may not notice it without an alarm.
Frequently Asked Questions
How Does Carbon Monoxide Affect Pets Differently Than Humans?
Carbon monoxide affects your pets faster and often earlier than it affects you because they’re smaller, breathe faster, and spend more time indoors near floor level where CO can pool. Birds are especially vulnerable due to their respiratory anatomy. Species-specific COHb thresholds vary, but lethal ranges overlap cats, dogs, and humans. You may miss early signs because cats hide illness and animals can’t report symptoms.
Can I COnnect CO Detectors to a Smart Home System?
Yes—you can connect CO detectors to a smart home system if you choose Wi‑Fi or hardwired interconnected models with supported apps. You’ll pair devices on 2.4 GHz Wi‑Fi, scan a QR code, and enable mobile alerts and shared monitoring. Use UL/CSA-listed alarms, install per NFPA 72 and the manufacturer’s spacing rules, and don’t disable local 85 dB sounders or interconnect features.
Are Low-Level CO Monitors Better Than Standard Alarms?
Yes—low-level CO monitors are better for early warning; they’re your canary in the coal mine. You’ll get readings starting around 10–30 ppm and alarms that can trigger near 25 ppm in about a minute. Standard UL 2034 alarms often won’t sound below ~30 ppm and may wait hours at 70 ppm, so you can’t rely on them for chronic exposure or vulnerable occupants.
What Are Carbon Monoxide Levels Considered Dangerous in Ppm?
You should treat carbon monoxide as dangerous when it’s sustained above 9–10 ppm for 8 hours, above 25–35 ppm for 1 hour, or above 90–100 ppm for 15 minutes (WHO). OSHA permits 50 ppm as an 8-hour TWA, but you shouldn’t rely on that for home safety. At ~70 ppm you can develop symptoms; 150–200 ppm can disable you; 400+ ppm is life-threatening.
Does Homeowners Insurance COver CO Detector Installation or Replacement?
No—your homeowners insurance typically won’t cover CO detector installation or routine replacement. Why assume it should? You’re expected to treat detectors as maintenance and keep them operational to meet policy conditions and state code. You may get coverage only if a covered peril (e.g., lightning/surge) damages an existing unit, not the install labor. You can often earn 5–20% premium discounts with UL-listed, interconnected, monitored alarms.
