About 90 mins. This was a silly mistake of mine in leaving behind my scarf in office in a rush to catch the bus. It happened over 15 years ago whilst in my final year at university.<br />
Bus (night bus) did not turn up and had to wait and wait and wait.<br />
Pulling my jacked up to sticking my nose and mouth inside the collar.
I am not in -0F weather often, but I have been. <br />
I have never had formal nose/mouth protection, but in the -43F I once experienced, I covered my mouth/nose with my gloved hand the entire time (in and out of a heated vehicle a dozen times in an hour). It was very uncomfortable, and if I'd not been young and full of myself, it probably would have been downright scary. I also had a beard which provides *some* mouth/nose protection... and boy did it ice-up!<br />
I was in -17 once a few years ago and it was not bad at all... I did not have any nose/mouth protection, but it was also *very* sunny... early morning, hot high-desert/mountain sun... it went from -17 at 7 AM to +17 at 9 AM while I was out in it the entire time... it was a magical moment.<br />
In the second incident, I think the "local" temperature around my face (in still air) was higher... I remember feeling like there was a bubble of heat/humidity around my head... and in fact, I was exerting a lot at the time (fixing a well pump) and even broke into a mild sweat at one point and noticed that there was steam boiling off of me. At that point, it was probably closer to 0F... the -17 was just at sunrise as I arrived at the well location...
1) How many times does this Q need to be asked?<br />
2) -2F isn't "extremely" cold...it was 8F in Boston today and I had no mouth/nose protection at all for up to an hour.<br />
3) In order to swell, a gland takes prolonged exposure. "instant" death is highly unlikely.
About 12 hours.
A few degrees below zero, and I do remember my neck feeling swollen. These days I wrap up better.