The valleys of Southeast Norway are prone to cold inversions in winter, trapping a lot of crap that just hangs around in the air. In addition to smoke, asphalt dust thrown up by steel studded car tires has historically been a problem.
D vitamines do not pollute! more and more research indicating their great benefit as protective against covid-19 (well I should not have told every polluter here about it)
Face masks causes more climate gasses (production) than a few farts, the people breathing through them are likely the same that want to kill cows because they fart, this to save the planet! Strange times!