Silent But Deadly

Carbon monoxide poisoning risk increases in winter


Every year 50,000 people end up in the emergency room with accidental carbon monoxide poisoning — but they’re the lucky ones. According to the Centers for Disease Control and Prevention, 430 people die each year due to accidental poisoning from this silent killer.

Carbon monoxide leaks can happen at any time of year resulting from everyday appliances that utilize gas or propane, like clothes dryers and water heaters. The winter months bring increased risk as people are more likely to use various heating devices.

REAL-TIME THREAT: In 2019, Thanksgiving dinner came to an abrupt halt for actress Anna Faris and her family when they began to fall ill from the effects of carbon monoxide poisoning while on holiday at their North Lake Tahoe home. Courtesy screenshot

“The combination of increased use of fuel burning devices, along with doors and windows being closed and limiting the amount of fresh air circulating in a home in times of cold weather, increase the risk of carbon monoxide poisoning during winter months,” North Tahoe Fire Protection District Chief Steve Leighton explained in an email to Moonshine Ink.


Carbon monoxide is a gas created when fuels like gasoline, wood, coal, natural gas, propane, oil, and methane fail to completely burn.

“There are a multitude of reasons for incomplete combustion, such as smoldering logs, a pilot light that is ‘on’ and releasing gas, but the flame has been blown out, etc. Blocked vents after a heavy snowfall could also increase the chances of carbon monoxide poisoning,” Leighton noted. “[Carbon monoxide] is extremely pervasive as it has a specific gravity similar to ambient air. This means [it] can easily spread all over a house. A malfunctioning forced air furnace can very quickly charge an entire house with dangerous levels of carbon monoxide.”

Aside from snow-covered vents, the winter months bring other poisoning and leakage risks. During power outages, improperly operated portable generators can result in carbon monoxide seepage into the home. Leighton stressed that portable generators should be kept outdoors and far away from open doors, windows, and vents to avoid a buildup of toxic levels of carbon monoxide indoors. Propane leaks can also be a danger, so snow stakes should be used to indicate the locations of the tank, valve, regulator, plumbing — any component related to propane use that could sustain damage. Heavy snow, shifting and shedding snow, as well as ‘glacial shifting’ that occurs from the thawing and freezing of snow and ice, are also potential hazards.

“Propane runs similar to the way water does, so if a snow load creates a leak or loosens a connection, the propane will flow under the snow following terrain features and will pool when it gets to a low point, where it will off-gas or find a source of ignition,” Leighton explained. “This creates the risk of a fire/explosion if the leak finds an ignition source, or carbon monoxide poisoning if it does not combust. This could impact multiple houses, not just the location of the leak.”

The Carbon Monoxide Poisoning Prevention Act, requiring the installation of carbon monoxide alarms in every single-family home with an attached garage or fossil fuel source, went into effect in California on July 1, 2011. So, with most alarms having a seven-year sealed battery, those detectors installed when the law passed are now expired and due for replacement. In addition, inner components can degrade over time, which is also a cause for replacement every five to seven years.

“If a dwelling hasn’t had an activity that would require an inspection since the code was adopted, a homeowner may not be aware of this important safety requirement,” Leighton added.

Neighboring Nevada, which also requires carbon monoxide detectors in all new construction, similarly does not require retrofitting older homes with the devices but does strongly recommend their use by residents.

The maximum recommended carbon monoxide level is 9 parts per million, and while it’s well known that carbon monoxide is colorless, odorless, and tasteless, most people are not aware that carbon monoxide has over 200 times the affinity with hemoglobin than oxygen does, the chief explained. This means hemoglobin is 200 times more likely to grab onto carbon monoxide than it would oxygen.

“It will literally bump oxygen off of a molecule of hemoglobin,” he said. “Once carbon monoxide attaches to hemoglobin it’s very difficult to get rid of it. It binds to carbon monoxide 210 times more tightly than oxygen. Carbon monoxide has a half-life in the blood of four to six hours, requiring high dose and sometimes even hyperbaric oxygen to get it out of a victim’s system.”

In his department, Leighton’s firefighters say they’ve seen more individuals killed by carbon monoxide poisoning than they have by fires.

“Carbon monoxide poisoning is very insidious,” he said. “It starts off gradually, mimicking cold and flu symptoms, altitude sickness, or even just general fatigue. Malaise and fatigue impair the victim’s ability to take action. Cognitive ability becomes gradually and unnoticeably impaired. Then, a victim feels compelled to just take a nap — a very treacherous and deadly slippery slope that traps its victims.”


  • Juliana Demarest

    Juliana Demarest is a Jersey girl with ink in her blood. She fell in love with print journalism at a young age in the '80s when her Uncle Tony would take her to "work" at his weekly paper. In 1997, she co-founded a weekly newspaper in North Jersey. One day, she went to photograph a local farmer for a news story. She ended up marrying him and leaving journalism to become a farmer's wife. In 2010, they packed up their two children and headed to Truckee in pursuit of the outdoor life. She didn't realize just how much she missed journalism until she joined Moonshine in 2018 after taking time off to be mom. Connect with Juliana

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