Category Archives: cold

Maybe clothing technology really hasn’t gotten better

Early in the 20th century, explorers were busy trying to reach the poles and climbing mountains, simply because they were there. The casual observer from modern times must wonder how they were able to tolerate such cold temperatures without the high-tech fabrics available today. The mental images of Amundsen, Scott, Peary, and other cold weather explorers are often viewed as men laden with incredibly bulky furs and wool garments. How on earth could they achieve anything wearing that kind of clothing?

Credit: National Geographic/The Wildest DreamThat question has particular merit when considering the legacy of George Mallory and Andrew Irvine. They died in 1924 while attempting to summit Mt. Everest, almost 3 decades before Hillary and Norgay were able to do it successfully. Mallory’s remains were found in 1999 at 8157m, and his clothing was removed for testing before he was buried. After 3 years of intense study using multiple methods, they were finally able to definitively say what he was wearing.

But that only answers part of the question. Now that we know what he was wearing, was it enough to keep him warm but still allow freedom of movement needed to climb mountains? To test this, they simply replicated the fabrics, which were layers of silk, cotton, and wool. This was then covered with an outer layer of gabardine, faithful to the original made by Burberry.

(As an aside, many readers may not be aware of Burberry’s prowess in making clothing for polar expeditions. Like Abercrombie and Fitch, the clothing you can buy today is nothing in comparison to the rugged outdoor items one used to be able to purchase.)

So with that part answered, all that was left was for someone to climb Everest wearing the replica clothing. And Graham Hoyland did just that in 2006. He didn’t summit, but he did learn that the fabrics were light, comfortable, and more importantly, warm enough to use during the day. They were not, however, thick enough to survive a bivouac on the mountain in his opinion.

The part that made the outfit ingenious was the different fabrics of the alternating layers. This allowed decreased the friction between the layers, allowing movement with much less energy expenditure. This was demonstrated when tests comparing Scott’s to Amundsen’s layered garments showed a 20% decrease in said energy doing the same activity when more “slippery” fabrics were used (silk and furs versus wools). The same scientist also showed that Mallory’s fabrics would have been able to protect all the way down to -30C in calm weather.

Sadly, calm weather they did not have. A blizzard came upon them as they approached the summit, and they were last seen on one of the Three Steps. Whether this storm made them turn back or not, it certainly would have predisposed them to hypothermia. As to whether Mallory and Irvine actually summitted? We may never know, unless someone finds Howard Somervell’s camera with proof.

While these findings have done away with the myth that Mallory’s expedition was ill-prepared (based on photos from base camp), what they really show is that modern synthetic fabrics have only incrementally made gains in thermal protection, weight, and function. The argument can be made that tailoring them to fit properly is as important as the material itself.

I wouldn’t try to climb Everest in any modern garment made by Abercrombie or Burberry though.

Mountain Clothing and Thermoregulation: A Look Back
http://www.ncbi.nlm.nih.gov/pubmed/22441098

Additional Readings
http://www.alpinejournal.org.uk/Contents/Contents_2007_files/AJ%202007%20243-246%20Hoyland%20Clothing.pdf
http://www.independent.co.uk/news/world/asia/mystery-at-the-top-of-the-world-did-george-mallory-make-it-to-the-summit-of-everest-before-he-died-2063196.html
http://news.bbc.co.uk/2/hi/science/nature/5076634.stm
https://dspace.lboro.ac.uk/dspace-jspui/handle/2134/9716
http://thewildestdream.com/

Wear the helmet anyway

CC-BY-2.0 Søren HovenHelmets continue to be recommended or required by multiple ski resorts worldwide. The main thinking is that prevention of traumatic causes of death will directly reduce mortality from avalanches and other alpine trauma. That being said, the authors of this study wanted to see if perhaps wearing a helmet also slowed progression of hypothermia by nature of insulating the head.

It makes sense. We are taught starting in grade school that most heat is lost from the head. Since we now know this statement by itself isn’t true, you move on to the real meaning of the statement, which is: you lose most of your heat through any part of the body that is uncovered. Thus, if you wore a hat but no pants, you would lose most of your heat through your legs. See how fun this is?

So the theory behind covering the only part of your body left uncovered while skiing isn’t too far out there. But does it slow cooling of simulated avalanche victims or not? Of note, their secondary hypothesis was how closely the temperatures between 3 different probes (esophageal, capsule, and rectal) would correlate.

Unfortunately, this study can’t tell us the answer to the first question. Their power calculation required 11, they only got 9 participants, and only used data from 7. 1 declined to be buried a second time for the control, and another had a poorly functioning temperature probe, and apparently could not swallow the esophageal probe, limiting data collection.

While their data does not show a significant difference in temperature between insulated participants and those without, there are possible confounding variables. Most people who aren’t sedated will hold their head off the snow, creating an air pocket of insulation. This is likely the reason for the difference between this study and an earlier one using water, as you can’t keep a submerged head out of contact with water. Also, they still had a Gore-Tex hood protecting their head from snowmelt, likely also reducing heat loss. The participants without helmets subjectively rated their experience as “colder”, for what it’s worth. Let’s not kid ourselves though. Nobody advocates using helmets solely for thermal insulation.

The good news is that the three different probes did correlate in temperature as far as rate of change. The absolute values of temperature were different enough that there still needs to be further work towards finding the ideal method of measuring temperature. But since we aren’t using the gold standard of pulmonary artery temperatures, we might as well stop (or significantly reduce) doing rectal and esophageal probes, as the discomfort of these likely reduces study participants. As capsules become more reliable, expect them to become the overwhelming favorite for future temperature studies.

Effect of Head and Face Insulation on Cooling Rate During Snow Burial
http://www.ncbi.nlm.nih.gov/pubmed/25281588