Life at the Pole was going to take some getting used to. Aceatazolamide (Diamox – a type of diuretic) was going to help, by allowing improved acclimitisation, and improving sleep quality. But each morning, I was waking up feeling like I’d drunk two dozen beer the night before, purely due to the dry air, and feeling that the seven and a half hours I had slept for instead was only four.
The geographical altitude of the pole is 9301 ft (yip, everything’s measured in imperial units around here). However, the ambient atmospheric pressure which gives a physiological altitude normally sits much higher. The reason for this is two fold. Firstly, the spinning of the earth means that the earth and its atmosphere surrounding it are not spherical, but instead are a oblique spheroid – effectively a sphere that has been squished from the poles and bulges in the tropics. Due to centrifugal force, mass gravitates to tropics, similar to clay on a potter’s wheel. The means that not only is the earth’s diameter thicker at the equator – Mt Everest is not the highest peak when measured from the centre of the planet, it is instead Chimborazo in Ecuador, South America – but also, the atmosphere thickness and density is greater in the tropics, and at it’s thinnest over the poles. Secondly the atmosphere over the poles is colder and more dense, so for a rise in altitude, you pass through more atmosphere, so the pressure drops quicker as you go up. So the physiological altitude average is 10,583 ft (3226 m) but often we see it over 11,000 ft.
The proportion of oxygen in the atmosphere stays constant despite the altitude (at 21%), but the barometric pressure drops. Therefore, in a 1m3 box the ratio of O2 to N2 is the same as at sea level, but the number of particles is about 30% lower than at sea level. Due to the way we humidify air when we breath it, what is called the partial pressure of oxygen (the pressure that oxygen makes up of the total air/barometric pressure) in the air we breath falls from 149mmHg at sea level to around 100 mmHg. Thankfully our bodies have redundancy in terms of extracting oxygen from the air due to the way that haemoglobin that transports oxygen to the tissues that need it can become well saturated even if the pressures fall significantly. Therefore, even though we are breathing in 1/3 less oxygen per ml than at sea level, when we measure most peoples saturations up here, most people still have saturations around 88-92% (normal is 97-100%).
This lower saturation though does hammer your exercise tolerance. Running two miles on a treadmill becomes a solid initial achievement. Taking a couple of boxes outside and walking 200m with bulky ECW gear means you need to stop and take a breather for five minutes. Even walking up the stairs initially required pacing yourself.
The low oxygen also affects the region in your brain that is responsible for stimulating breathing. Diamox helps a bit, but the sleep takes some getting used to. Coupled with this is sleeping in a single bed designed for people shorter than 6 foot – the Americans call a single bed a double which confused me in my search for sheets on the first day! I had always prided myself on the ability to drop off to sleep within 5 minutes, and only wake with an alarm 6 or 7 hours later. But now I’ve found I was waking more frequently and more unsettled than normal. The constant light is not a major issue for me, as the blinds on the windows are pretty effective. But without a natural external stimulus to tell you the time, you have to be careful to watch the clock, otherwise you find yourself sitting in the galley chatting away, with the light streaming in, oblivious to the fact that it was well past midnight!
The humidity of living in such a cold environment is one of the biggest factors you notice quickly. The amount of moisture that air can hold is dependent on its temperature. The air outside is at times close to 100% saturated, but often over 50%. However, when that air is warmed inside, the moisture contents stays the same, but the moisture carrying capacity increases dramatically as it is heated 80 degrees C! Therefore the resulting humidity in the station is normally in low single digits (~1%) which is profoundly noticeable. In comparison, most aircraft cabins are 14-19%, and the effect there is easily noticeable. Living here, going to bed well hydrated is normally followed by waking up with your tongue caked to the floor of your mouth. Luckily there were a supply of humidifiers (not dehumidifiers which I was used to using!) on station which make things a bit more tolerable. Persistently cracked lips, bloody noses and dry eyes are just some of the things that you can notice. Let alone if you actually decide to have a couple of beers the night before if it is a week when not on call.
Sunday night is always a highlight, as that is normally the day I get my washing done. Hanging a full load of soaking laundry in my small room means that there is an extra litre of so of moisture to evaporate into the room during the course of the night, leaving you just a little less parched in the morning, and with nice crisp dry washing in the space of 12 hours.
The low humidity does have its upsides. Spill a glass of water on the carpet, no problem, dry an hour or so later. Being less sweaty in general is key when we are limited to four minutes of showering per week! And as nothing ever really gets wet, your clothes are always dry when you are outside, which means you conduct less heat away that if your gloves were always a bit damp etc. One of the downsides is that the snow drifts, whilst nice and powdery, are too dry to make snowballs out of. The snow (well its actually drifted ice crystals) doesn’t stick to itself so getting your mate with a surprise snow fight is an epic fail.