Monday, July 6, 2020

Carbon Dioxide Poisoning in the Mountains

We celebrated New Years Eve in the backcountry. We hiked pretty far back to climb some -- as of yet unknown -- ice climbs. It was a really cool trip, and I'll never forget it. We were in one of the most beautiful places you could imagine, but...

Shortly after midnight on January 1, 2000 -- the first day of the new millennium -- I woke up, gasping in my tent. My girlfriend, now wife, woke up too. There didn't seem to be enough air inside the fabric.

I unzipped the fly, and then unzipped the vestibule to find that we were completely covered in snow. There wasn't a single area of the vestibule that wasn't covered. For all intents and purposes, a storm that brought a combination of wind and two new feet of powder, had buried us.

The closed system resulted in mild carbon dioxide poisoning. We were breathing in the air that we'd breathed out.

I have worked as a professional guide since the year 2000, and since then, I have seen the effects of mild carbon dioxide poisoning several times. And it's always the same. People go to sleep. It snows heavily. They wake up feeling a shortness of breath. They clean off their tent, and then they go back to sleep.

Deep new snow on Mt. Baker.
This was a trip where I woke people up several times
at night to make sure that they cleaned new snow off their tents.

In more severe cases, the person may take a little time to recover. Sometimes it takes up to a full day. A longer recovery can feel like a hangover. 

Severe cases tend to happen when several factors come together: (1) There's a significant snowstorm. (2) The tent is not cleared off. (3) A person is in a tent alone. When there are two people in the tent, it is likely that one will wake up more quickly than the other to deal with the problem. And (4) the person in the tent alone is a heavy sleeper.

It would be an incredibly rare situation where something like this lead to a fatality. The simple reality is that most people wake up when they feel like they can't breathe. Some don't wake up right away, which can lead to a more severe "hangover" style case.

The normal atmospheric concentration of carbon dioxide is 0.04%. Sensitive people may start to feel the effects of carbon dioxide when it reaches 1% or 10,000 ppm (ppm = parts per million, a calculation of how many molecules there are of a given substance in a million particles). Most people will wake up when it reaches 1.5 to 2% or 15 to 20,000 ppm. Real health hazards come at 4% or 40,000 ppm. And the risk of death doesn't arrive until you get to about 8% or 80,000 ppm, long after you've awoken to fix the problem.

So, now we get to the real meat of the question.

Most guide services in the United States are requiring the use of masks or cloth face coverings when a physical distance of six feet or more cannot be maintained in an outdoor environment. At AAI, we require face masks under these circumstances. It is part of our COVID-19 operating plan.

Masks are required at AAI when a distance of six-feet or more
cannot be maintained in an outdoor environment. When moving on trails
we require there to be at least twelve-feet between individuals without 
masks due to increased exhalation with work. 

There are a number of internet rumors out there about the dangers of face coverings and face masks. These are unequivocally, bunk. Yes, if you duct taped a plastic bag around your head, you'd have a problem. But a cloth face covering or a mask isn't a plastic bag. Air molecules are really small and can certainly get in and out. 

The following is from an article in Fatherly:

In one small study published in Respiratory Physiology and Neurobiology, twenty subjects wearing surgical masks walked on treadmills for one hour. Scientists measured their blood oxygen and carbon dioxide concentrations, respiratory and heart rates, and core temperatures. After that hour, the scientists found no significant change in these measurements.
Masks and face coverings are used to mitigate hazard from the coronavirus by keeping large droplets in. The face coverings are not meant to keep the disease out. They make it safer for other people to be around you, if you have it and don't know it.

We've had people say things like, "but, you can smell a fart through blue jeans." Or some other variation of that, to say that coronavirus will get you with or without a mask. It should be obvious, but a fart is a gas, and we're trying to stop large droplets. And indeed, if there are large droplets with your flatulence, your jeans would block that too...

(Click to Enlarge)

If you absolutely cannot abide by a mask/facial covering, then you can use a face-shield. Locally, when people arrive in public buildings and say they can't wear a face covering, they're provided a face-shield. 

Indeed, some studies suggest the the use of a face mask, combined with other "social distancing" techniques, may reduce the spread of the coronavirus by up to 85%.

So that's it. Carbon dioxide can be bad, but backcountry travelers are most likely to deal with it in their tents, not in their face coverings.

One last thought for the face-mask doubters. Arjun Arya, MD, made a great point about this. "If you're worried about C02 accumulation from masks, our climate crisis is really going to blow your mind..."

--Jason D. Martin

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