Speaking of swaps, I have a good friend, now retired, but he invented a gadget to measure the particle count in the atmosphere. One of the places he ended up going with one was 'Siberia'. He wasn't clear on exactly where in Siberia, but someplace where there was a lot of atmospheric particulates - maybe Norilsk? He'd spend hours in a cargo plane with a door open. He left the US with lots of high-tech mountain expedition stuff, like when he'd go to Antarctica, came back with fur-everything. Here in the US, those furs are worth quite a lot, but I think, to the Siberians, the gear he had was made of pure unobtanium. He said the furs kept him a bit warmer but were harder to move around in. I tried one coat on, very heavy - and I started to sweat almost immediately (cool day in SF).