-40 is really cold and dangerous. I would think a face mask is in order to keep from losing one's nose. Too cold for me!
You are right. Cold and dangerous. But manageable. Every year I lived in Winnipeg during the aughts, at least one or two mornings per winter I would get up to take the dogs on their morning hour long walk around 7:00 am and it would be minus 40 (without windchill). With the right clothes and boots and if the wind wasn't howling, combined with vigorous walking with the dogs, no mask required.
But it fast becomes a problem if you are unprepared. BTW, my setters thought it was just fine. Only when they got old did they want to shorten the walk because of cold temps.
Skiing, the worse I ever got into near minus 30C, but the activity of skiing kept me warm plus the sun feels warmer at altitude and I never tried to take on the cold when there was a high wind. I feel like a real rookie and don't know how to dress for cold weather particularly so with all the new cold weather products that are now on the market. Getting good cold weather gear is next to impossible here in warm Texas.
I have always used silk under wear, under socks and glove liners. Then a layer or two of wool, then a jacket with or without a liner and a synthetic material on the outside of the jacket that could behave as a wind break. Good gloves or mittens, wool watch cap, full mask and ski mask. Now there are so many synthetics out I don't know which is best to replace the silk and wool. The trouble with wool is it can be attacked by moths and is hard to keep clean. Silk is easy to care for but I have always felt the first layer was the most important and wondered how it might be done differently
I would be interested to hear how you Canadians dress for cold weather. I sometimes think you have just grown to the cold. Particularly so when I see northern people jump into freezing water as recreation.
