What Are the Signs of a Carbon Monoxide Leak?

Carbon monoxide (CO) is called the “silent killer” for a reason. It’s clear, scentless and hard to recognize without the right tools. If it collects in your home, it can quickly become a danger for you and your family. So, how do you guard against something you can’t see, smell or taste?

The key is to have carbon monoxide detectors. These small alarm systems are your first line of defense, warning you about the presence of CO gas before the situation gets dangerous. But other than a detector going off, how can you recognize if there’s a carbon monoxide leak in your home? Below are 10 clues to watch out for.

1. Condensation on Windows Closest to Appliances

If you spot heavy condensation on your windows, particularly near a fuel-burning appliance like a gas fireplace, this could indicate that there’s an issue with ventilation. While humidity or condensation itself doesn’t always mean CO, this still should be checked out.

2. Discoloration or Soot-Like Stains

Combustion-based appliances should always have clean, clear exhaust. If you find brownish-yellow or sooty stains around a heater or gas fireplace, there may be combustion issues. This can be a sign of a carbon monoxide issue.

3. Exhaust Fumes Indoors

If you can notice exhaust indoors, you are at risk of carbon monoxide exposure. Fuel-burning appliances like cars, charcoal grills and generators should exclusively be used outdoors to reduce the risk of exhaust fumes indoors.

4. Soot in or Around a Natural Gas-Burning Fireplace

Your chimney should channel smoke and other gases up and out the chimney. Finding soot inside or around the fireplace is a warning sign, especially if there’s an unusual amount. An obstructed flue in the chimney could be the reason carbon monoxide is backdrafting into your home.

5. Weaker or No Draft in the Chimney

Staying on the topic of chimneys, a properly working one needs the solid updrafts to fully ventilate smoke and other fumes. If you detect reduced ventilation or even no draft at all, the chimney may be blocked, pushing carbon monoxide back into your home.

6. Yellow or Flickering Flames

Gas-powered appliances should produce a steady blue flame. If the flame is weaker and yellow (and it’s not a decorative gas fireplace), it can mean the gas has combustion issues and could be emitting carbon monoxide.

7. Solid Fuel Fires Burning Slowly

When your wood-burning stove is burning slower than usual or has trouble maintaining a flame, it could be dealing with a ventilation issue, increasing the risk of CO buildup.

Common Health Symptoms of CO Poisoning

If you don’t catch the initial warning signs of a carbon monoxide leak in time, the next one might come from your health and well-being. Symptoms of CO poisoning may involve:

Flu-like symptoms
Headaches
Dizziness
Nausea or vomiting
Shortness of breath
Confusion
And fatigue

If you or anyone in your family starts getting sick, especially alongside any of the above signs, move outdoors immediately and contact emergency services.

Preventing CO Leaks and Top Safety Tips

Prevention is always better than a cure, especially in the case of CO gas exposure. For the most basic safety, check that there are carbon monoxide detectors in all the right places. Building codes mandate them close to any bedrooms, on each level of your home and in rooms with appliances like a gas stove or water heater. For an additional safety measure, it’s best to use interconnected detectors so that as soon as one detects carbon monoxide, all of them will sound. Test these detectors monthly and swap them out when necessary, generally every five to seven years.

In addition to having enough carbon monoxide detectors, keep these safety precautions in mind: