Thursday, May 21, 1998 Base Camp (17,500')
Hello Mountain Zone, today is Thursday, 21st of May. This is Charles Corfield. I thought I would follow up from the previous dispatch with a description of one of the details of summit day which is: what is it like wearing an oxygen mask for so many hours? You may recall that we set off from the South Col about 11 o'clock at night, and we got back in roughly the middle of the following day. What you're looking at is a twelve hour period where you are wearing an oxygen mask the whole time. So, what does it feel like?
The first thing to note about an oxygen mask is: it's big. It covers everything from the bridge of your nose down over your mouth. You have straps coming up over your ears, and since you probably want to wear ski goggles at the same time, the two straps are competing for the same real estate at the back or the top of your head, depending where you're wearing it.
The mask is pretty heavy; it's fairly thick rubber, and where it lies against your face, it's lined with a chamois leather to make it more comfortable. As you move your head around, particularly if you want to look down, the mask will tend to shift under it's own weight.
Getting back to how does the mask work. The systems we use is called open circuit masks. When you breath in, there is a big snout in front, a diaphragm, which will open, and also there is a little inlet valve very near to your lips where oxygen will come in from a bladder. Your oxygen cylinder, which weighs five to seven pounds, is continuously filling the bladder so when you breath out, the valve of the bladder closes, and you breath out through the big snout. If you have a little gap between the mask and your chin, air will exit there too.
One of the experiences is there is this continual hiss because you are either breathing in through a small aperture or breathing out small aperture. So this tends to deaden your sense of the environment around you. The mask is also pretty warm. Normally when you're walking around at these altitudes, the air is cool so you have a rather nice refreshing breeze over your face. So when you're climbing with an oxygen mask, it's warm, the air feels moist because of the condensation within the mask, and some people find it a little claustrophobic.
One of the issues with your face once the sun rises on summit day is that you need to put eyewear on, and this is just a lousy problem to solve because if you put ski goggles on, ski goggles have a pretty nice form factor and they are competing with your oxygen mask. So as you push down the ski goggles, you tend to push the mask off your face, and that's no good cause you need the oxygen. On the other hand if you push up the mask, the ski goggles ride up, a gap opens up, and then the goggles will fog very quickly because of exhaled air. So there is this continual problem during the daylight hours of how the hell do you keep your eyewear free of condensation? I'm afraid all these anti-fog agents that we're used to from ski resorts, they do not really work very well at altitude. Indeed, if for some reason, it clouds over, the breeze kicks up, you can get instant icing on your ski goggles. That's one of the reasons why I carry around a very small container of antifreeze so I can deal with the problem.
The best conditions are dry weather with a moderate wind which can keep blowing through your ski goggles and keep the moisture from building up on the inside. You might well ask, 'well why don't you wear something like glacier glasses instead which would allow more air movement?' The problem is when you try and put these glasses on over an oxygen mask, they tend to ride out fairly far out in front, and now you're exposed to a lot of ultra violet coming in from the side. I've seen a couple of climbers try to live with this scheme, but I suspect that they've all got some snow-blindness of some variety by the end of the day.
Other problems that you encounter with the oxygen mask are: it's cold. You've got water vapor in the air you're breathing out, and it's going to go somewhere. If it happens to go back down into the bladder, which it can, it will freeze. Yours truly had an experience on summit day where the whole inlet mechanism froze up enough that I was getting no oxygen at all; the bladder filled up until it was taut; but nothing was coming into the mask. I had for a while, at sunrise, my own experience of climbing Everest without oxygen, which wasn't quite the horrible experience I'd expected; things slowed up, but it was not a disaster.
What finally solved that problem was the fact that the sun came up over the horizon shortly after four in the morning, and the incident heat from the sun eventually just melted the ice in the inlet and then I was back in business. I should add, all during this time I managed to keep up climbing with the rest, and as I say, it was not as bad as I had anticipated, by any stretch of the imagination.
Breathing oxygen, it's very dry. A lot of people who have the experience of their throats getting incredibly dry, saliva in their mouth basically turns to rubber cement, of the same sort of consistency, and heaven forbid that their nose should even dream of running because there is very little you can do about the accumulation of mucus/snot in your oxygen mask. It's just going to carry on building up there during the day, and you'll have to live with it. A number of people notice that just breathing hard all day kind of dries up your lungs somewhat, and so people get somewhat bronchitic at the end of the day.
I don't want to make it sound like it's some chamber of horrors, but just to relate to you that the oxygen mask, it's an unusual situation to be in, it lasts about 12 hours, and you're fairly glad at the end of it to be able to put it away. On the other hand, it really does make the climbing of the summit possible, and it also makes our ability to climb at a pretty good climbing rate possible. Last year for example, I recall that we were climbing from the South Col to the Balcony at about a rate of about 600 plus feet an hour, which is pretty good at those altitudes, and we were not straining ourselves doing it. So that concludes some thoughts on what it's like to wear an oxygen mask on summit day. This is Charles Corfield, Everest base camp.
Charles Corfield, Expedition Science Manager
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