On the night of June 6, 2018, a snowstorm hit the climbers’ camp at 14,200 feet on Denali. Overnight lows hovered around 0°F that week. At around 9 p.m., a climber who felt “funny” went out for some fresh air and returned to find his tent mate in the midst of a fit. Carbon monoxide from a stove in the tent had built up to near lethal levels. If the sick climber hadn’t come out when he started feeling unwell, the two would probably be dead by morning.
Carbon monoxide, a deadly, colorless and odorless product of combustion, kills more than 400 people a year in the United States. Most fatalities are household exposures to faulty heaters or misplaced heaters, but hikers and climbers who use stoves in confined, poorly ventilated spaces (think zipped your tent in the middle of a blizzard) are at high risk.
When levels reach around 70 parts per million (ppm), those exposed report headaches, nausea, dizziness, or just plain feeling sick. Once levels exceed 200 ppm for prolonged periods, serious consequences such as unconsciousness, confusion and even death follow. A 2013 study showed that the concentration of the deadly gas depended on both the type of tent and the fuel used. Concentrations reached over 150 ppm when burning white gas in an all-season tent and over 200 when unleaded gasoline was used as fuel. In some studies, concentrations reached toxic levels within minutes, although the rate of increase depends on the type of fuel and the degree of ventilation. A stove burning white gas in a three-person, four-person tent reached 100ppm in just six minutes.
After the incident on Denali, National Park Service rangers used supplemental oxygen and a portable hyperbaric chamber to treat poisoned climbers. Their most important action, however, was to remove their patients from this toxic tent. Both climbers improved and were evacuated to safety when weather conditions cleared.
High altitude climbers aren’t the only ones at risk of carbon monoxide poisoning. In 1999, the CDC reported two separate incidents at Georgia campgrounds in which two adults and four children died using a propane gas stove in one case and a charcoal grill in the other, for warmth on nights. cold. The two youngest victims were seven years old.
Carbon monoxide poisoning is preventable for hardcore climbers and weekend campers. Of course, it’s cold. The risk can be reduced by choosing to use a stove in a vestibule rather than inside the tent itself, and ensuring that snow does not block doors and vents, cutting off circulation air. Either way, ensuring adequate ventilation – or keeping the stove outside the tent – just might save lives.