You can’t see it. You can’t smell it. And you might not know it's there—until it’s too late. Carbon monoxide (CO) is often called “the silent killer,” and for good reason. It's a colorless, odorless gas that can build up in homes and cause serious illness—or even death—if not detected in time.
But what many homeowners and real estate agents don’t realize is this: you can have carbon monoxide in an all electric home, and carbon monoxide can come through air vents in a house. That’s why every home needs a carbon monoxide detector, no matter what type of appliances or systems it uses.
In this blog, we’ll answer all your top questions—like “Do all homes need carbon monoxide detectors?”, “How long does it take for carbon monoxide to leave the house?”, and “How to lower CO2 in house?”—plus give practical safety tips for your home or your client’s.
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What Is Carbon Monoxide—and Why Is It Dangerous?
Carbon monoxide is a toxic gas produced by the incomplete combustion of fuels such as:
- Gas
- Oil
- Wood
- Coal
- Kerosene
- Propane
- Charcoal
Any appliance or device that burns fuel—like a gas stove, water heater, furnace, fireplace, or portable generator—can produce CO. If these systems are not properly vented or maintained, CO can build up indoors.
The danger? CO binds to red blood cells, displacing oxygen, and deprives your brain and body of what it needs. It can cause symptoms like headaches, dizziness, nausea, confusion, or worse.
Can You Have Carbon Monoxide in an All Electric Home?
Yes, and this surprises a lot of people. “Can you have carbon monoxide in an all electric home?” The answer is yes, in certain conditions:
- If there’s an attached garage, a running vehicle can leak CO into the house through vents or shared walls.
- If a portable generator, charcoal grill, or kerosene heater is used indoors (during a power outage, for example), CO can accumulate.
- Fireplaces, wood stoves, or even nearby neighbors’ generators or garages can sometimes cause shared CO exposure in townhomes or apartments.
So even if a house is all-electric, it’s still smart—and often required—to have CO detectors installed. Carbon monoxide doesn’t care what your utility bill says—it just needs a fuel source.
Do All Homes Need Carbon Monoxide Detectors?
Yes. In fact, most states require carbon monoxide detectors by law, especially in homes with gas appliances or attached garages. Some require them in all homes, regardless of fuel type.
So, “Does an all electric house need a carbon monoxide detector?” From a safety standpoint, absolutely. CO can enter any home under the right (or wrong) circumstances.
Install carbon monoxide detectors:
- On every level of your home
- Outside each sleeping area
- Near attached garages or fuel-burning appliances
Choose alarms with both audible alerts and digital displays if possible. Combo smoke/CO detectors are also available and may meet local code.
Can Carbon Monoxide Come Through Air Vents in the House?
It can—and that’s one of the most dangerous pathways. Carbon monoxide can come through air vents in a house if:
- A fuel-burning furnace or water heater is malfunctioning
- A car is idling in an attached garage
- An improperly vented fireplace or chimney allows CO to recirculate
That’s why HVAC maintenance matters. Annual inspections of your furnace, water heater, and ventilation system can help prevent CO buildup and ensure air isn’t being contaminated and circulated through the home.
What to Do If You Suspect a CO Leak
If your CO detector goes off, act fast:
- Get everyone out of the house immediately.
- Call 911 or your local fire department.
- Don’t re-enter the home until professionals say it’s safe.
- Ventilate the home if safe to do so (open doors/windows).
Even if no one feels sick, take every alarm seriously. And if someone shows symptoms like confusion, dizziness, or vomiting, seek emergency medical help right away.
How Long for Carbon Monoxide to Leave the House?
Many homeowners ask, “How long for carbon monoxide to leave the house?” That depends on several factors:
- The level of CO in the air
- Whether the source has been shut off
- How well the house is ventilated
With windows open and the source removed, carbon monoxide levels may drop within a few hours. But without proper ventilation, CO can linger—especially in tightly sealed homes or basements.
To speed things up:
- Turn off the CO source
- Open windows and doors
- Use fans to promote airflow (if safe)
Always test the air again before re-entering fully.
Go beyond the basics and become your clients’ go-to resource for healthy living spaces! Empire Learning’s Healthy Homes (4-hour) and Healthy Home Fundamentals (3-hour) CE courses are designed to help real estate professionals like you understand the hidden health risks that can impact a home—and its value. From mold, lead, and radon to indoor air quality, asbestos, and pesticides, you’ll gain the knowledge to confidently address client concerns and highlight key features that matter in today’s market.
CO2 in the Home: What’s the Difference?
Many people confuse carbon monoxide (CO) with carbon dioxide (CO2). While CO is deadly at low levels, CO2 is a natural byproduct of breathing, cooking, and human activity. High CO2 levels, though not toxic, can cause:
- Fatigue
- Headaches
- Reduced cognitive function
Curious about how to lower CO2 in house or how can I test my CO2 levels at home? Here’s a quick breakdown:
How to Lower CO2 in House
- Open windows regularly to increase ventilation
- Use exhaust fans in kitchens and bathrooms
- Add houseplants (they help absorb CO2)
- Avoid overcrowding or over-sealing rooms
How Can I Test My CO2 Levels at Home?
- Purchase an indoor air quality monitor with CO2 sensors
- Look for readings under 1,000 ppm (parts per million) for good indoor air quality
Need a CO2 Filter for Home?
While a CO2 filter for home or CO2 scrubber for home exists, these are more common in commercial or lab settings. For most homes, improved airflow is the best fix.
Real Estate Tip: Highlight CO & CO2 Safety Features
For real estate agents, carbon monoxide safety is more than a checkbox—it can be a selling point:
- Point out new CO detectors or smart detectors
- Emphasize HVAC maintenance or new ventilation systems
- If the home is all-electric, explain why CO detectors are still installed—it shows proactive safety
Buyers with kids, elderly parents, or health concerns will notice—and appreciate—these details.
To Learn More...
For real estate professionals, understanding these concepts can be particularly valuable during discussions with clients about why REALTORS® and real estate agents are knowledgable professionals.
If you’re preparing for your Real Estate Continuing Education or looking to enhance your knowledge through a Real Estate Course, topics like Healthy Homes can help set you apart.
As part of your License Renewal Course or other Real Estate CE efforts, staying informed on foundational property concepts can make a big difference in your expertise and client relationships.