it's not the cold, it's the things you do to escape it, that make you sick. your buildings and carriages are sealed up like tupperware, into which you blow hot air, usually loaded with moisture. convection heating is cheap and easy, a very low budget way of making people feel warm. proper radiant heating and healthy fresh air are expensive and difficult to maintain. of course, you could just dress for the weather, but most of you don't.
i can't breathe in your world, i drown in my own perspiration every time i get on a bus, go shopping for groceries.
it was minus two here, and dropping, the last i looked, and my windows are open wide, as they always are, year round.
the air tastes like fresh water.