Carbon monoxide: The silent killer

Ah, the holidays. A time for friends and family to gather at the hearth, sharing food, drink and good cheer. But could your cozy fire be poisoning your guests?

It could be, and you might not even realize it. Is everyone a little sleepy? Complaining of headaches? Just the big dinner and the egg nog, you say to yourself. They’ll all feel better tomorrow.

Maybe. Or maybe they’ll feel better as soon as they leave your house and get some fresh air.

If everything in your home runs on electricity, carbon monoxide (CO) isn’t likely to be much of a concern for you. But if you have even one appliance that runs on gas or oil, or if you have a fireplace or woodstove, you need to know about the danger.

Where does carbon monoxide come from?

Combustion, or burning, is a chemical process that gives off heat and light as molecular bonds are broken and reformed. The fuels we burn contain carbon, and during combustion carbon atoms combine with oxygen atoms to form carbon dioxide (CO2; one carbon atom and two oxygen atoms) and carbon monoxide (CO; one carbon atom and one oxygen atom), both of which are released into the air we breathe.

When oxygen is plentiful — the chimney flue is clear, the gas furnace is well-maintained — combustion forms mostly CO2 with just small amounts of CO. But if there is an inadequate supply of oxygen — if the chimney flue is obstructed with leaves, for example, or if the heat exchanger in the gas furnace is cracked — increasing amounts of CO will be formed.

Carbon dioxide is a greenhouse gas and hazardous on a global level, but on a personal level it’s harmless. Our own cells produce CO2 as a normal metabolic byproduct and our red blood cells (RBCs) carry it away to our lungs, where we exhale it. The system works perfectly, with the RBCs off-loading CO2 in the lungs and picking up oxygen (O2) to carry back to the cells.

Carbon monoxide is different. It parks itself on RBCs in the spots designated for oxygen, and stubbornly hangs on. As you breathe in CO, RBCs become saturated and unable to carry O2, and your cells begin to starve and die.

This is why the first symptoms of carbon monoxide poisoning are usually drowsiness, confusion and headache — your brain cells are especially sensitive to oxygen deprivation. Unfortunately, these symptoms are more likely to make you settle in for a nice low-oxygen nap than to move away from the CO source.

How to prevent CO poisoning

The key is oxygen. As long as your fuel source has an adequate supply of O2, it will convert mostly to harmless (for you) CO2. If there’s not enough oxygen, though, the carbon in the fuel will form more CO — the deadly stuff.

  • Have your gas or oil furnace and gas water heater professionally serviced every year. You can have a life-threatening problem, such as a cracked heat exchanger, without noticing any difference in performace.
  • Inspect your chimney and firebox each year for cracks, leaks and soot buildup.
  • Never use hibachis, barbeques or camp stoves inside the house (or any enclosed space). They will quickly use up available oxygen and replace it with CO.
  • Never put aluminum foil over vent holes on the bottom of a gas oven.
  • Never use a gas oven to heat your house. A normally functioning oven already leaks some carbon monoxide into your home. With the flame turned up and the door left open, the oven will rapidly deplete oxygen in the room and begin producing increasing amounts of carbon monoxide.
  • Avoid letting your car run inside the garage, especially if it’s attached to the house.
  • Install and use portable generators outside in well-ventilated areas at least 20 feet from your home.
  • Install CO detectors on each level of your home, especially near sleeping areas; each detector should be at least 15 feet from any fuel-burning appliance to avoid false alarms.

Symptoms of CO poisoning

Symptoms of carbon monoxide poisoning
Click to enlarge

Carbon monoxide poisoning can be acute (all at once) or chronic (low level exposure over time). Symptoms depend on degree and length of exposure and are exacerbated by pre-existing health problems.

Carbon monxide is colorless and odorless, and because symptoms of CO poisoning are non-specific it’s easy to attribute them to more common causes. Acute symptoms can be flu-like, and chronic symptoms can mimic depression, dementia and a host of other conditions. Symptoms generally resolve when the CO is cleared from the body, but depending on the severity of the exposure there can be lasting effects.

Symptoms, from mildest to most serious, include:

  • Headache, nausea
  • Drowsiness, dizziness
  • Confusion, impaired judgment
  • Vision changes, vomiting
  • Shortness of breath, chest pain
  • Rapid pulse and respiratory rate
  • Loss of consciousness, seizures
  • Coma, respiratory failure, death

>>>> If you suspect carbon monoxide poisoning, leave your home immediately and call 911. <<<<

CO detectors are critical

CO detector
You need some of these.

One last thing: Even if you’re fastidious about prevention, undetected carbon monoxide can creep into your home. Because you can’t see or smell it, you need carbon monoxide detectors. You can get combination smoke and CO detectors or separate units. You can even get smart detectors that communicate with each other and with you via your mobile devices.

If you have battery-operated detectors, check the batteries monthly and replace them at least once a year. Consider tying the battery change to a significant annual event, like the day in November when daylight savings time ends and we “fall back” an hour.

More information

CO detector buyer’s guide

Carbon monoxide detector placement do’s and don’t’s

How to inspect a fireplace chimney

6 signs your chimney needs to be repaired

Generator safety

Potential new antidote for CO poisoning

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