Many tent campers don’t realized that carbon monoxide is a real hazard in all but the most well ventilated tents any time a heating source such as a wood stove, a low emission propane space heater, or a propane or gas lantern is used inside for any length of time.
While these appliances specifically warn against their use inside any tent as being a fire hazard, many don’t have adequate warnings about the potential danger from carbon monoxide. That was the case in eastern Utah, in June 2009. While attending a group event and camp out, two people died during the night inside their tent from the emissions of a small propane space heater. Later, the heater’s manufacturer was sued for inadequate warning labels and knowingly selling a hazardous device, but was found to not be liable.
Cold weather tent camping has a rich tradition of canvas wall tents with wood burning “packer type” stoves keeping away the winter chill.
Today numerous companies offer canvas and non-canvas single and double wall tents with stove jacks built in for the addition of a stove and stovepipe. In theory, this is touted as a “safe situation”. Combustion gases rise up the stovepipe and are exhausted to the outside world.
In an ideal world, stove pipes don’t get knocked over in the middle of the night by high winds or other unforeseen accidents… But in the real world, sometimes anything that can go wrong, will go wrong. Camp fire stories abound of groups of hunters waking up in the middle of the night coughing and choking in a smoke filled tent. Sadly though, they sometimes become very real news stories about fatalities caused by this same sort of debacle.
A similar situation happened to my Dad and Great Uncle back in the early 60’s during a cold weather elk hunt in western Wyoming.
In the middle of the night a large clump of snow fell onto their 3 man, military issue, canvas wall tent that they were heating with a stove-piped catalytic heater. Thankfully the falling snow woke them up, only to realize that they were both suffering the classic symptoms of carbon monoxide poisoning: severe dizziness, nausea, and pounding headaches. They were so sick that it ruined the rest of their long anticipated hunt and sent them home early. Fortunately they survived with no lasting adverse health issues.
Assumptions are made that since canvas is breathable, Carbon monoxide will not build up in this type of single wall tent– that it will rise and seep out though the pores in the single layer of canvas. This is not always the case. Carbon monoxide can be either lighter or heavier than air depending on the temperature. It permeates the localized environment and can only be exhausted from a confined space at the same rate as air. If the area is well ventilated and/ or the enclosure’s walls are very breathable, then toxic levels may not build up. But if the canvas is sheltered by a non-breathable rain fly of some sort, or if the tent sits in a significantly stagnant air pocket, the interior air may not be refreshed to an adequate degree to prevent carbon monoxide saturation. An inexpensive battery powered carbon monoxide detector is an easy and reliable way to monitor the air quality in this type of situation.
Now days it is common for many tent campers to utilized a “low emission” propane fueled (non-vented) space heater and possibly a gas or propane fueled lantern inside “outfitter style” double wall tents.
These tents get their “four season” rating partially due to the fact that they can be sealed up relatively tightly to prevent air leaks, and therein is the problem. They can also prevent an exhausting and refreshing of the interior air, and so the over use of any combustion powered heater or light source may quickly create a toxic air quality situation. Most outdoorsmen are aware of this and consequently limit the amount of time they will allow these types of appliances to operate… But let’s say they are dog tired from a strenuous day of hunting, and turn on the space heater just to take off the chill. They then lay down to read a book before falling asleep, and fall asleep? That last sentence they read may be the last sentence they will ever read unless somehow they wake up before being overcome by carbon monoxide.
Any type of combustion powered appliance is a real safely hazard in a tent, as shown by the previous examples. The most prudent choice is to forgo auxiliary combustion based heating and lighting sources, and rely on warm bed clothes and an appropriate sub-zero temperature rated sleeping bag.
But if you really feel the need for a space heater in your tent, as many do, four important guidelines should be followed:
- Carefully position the device away from combustible materials.
- Prudently limit the amount of time the device is allowed to operate.
- Do not allow yourself to fall asleep while the device is on.
- Set up a battery powered carbon monoxide detector in an area of the tent where it can monitor the main volume of breathable air.
The small price of less than $70 for a portable, battery powered carbon monoxide detector may literally be the best money you will ever spend. Although most carbon monoxide detectors have a written disclaimer against non-standard applications, experience shows that they do work perfectly fine in these improvised situations (provided, of course, that the batteries are not running low), and they are far, far better than nothing at all.