I've been wearing a heat exchanger mask for three winters now (
http://www.psolar.com/). I always used to get colds "from" breathing cold air, but since buying the mask that hasn't happened (yes, I know the cold didn't come from the cold air, but from the extra stress that the cold air caused to my immune system's ability to fight off existing germs ...).
The heat exchanger mask even helped me to ride 720 miles of Paris-Brest-Paris with a bad cold that turned into pneumonia by the end. Without the heat exchanger, any hard exertion (like climbing) would make me suck in too much cool air at once, triggering a coughing fit. So any time I would need to ride hard in cool, damp air, I just put the mask on. I still didn't finish PBP in time, because I just couldn't maintain my normal speed. But I'd never have made it anything like as far without the pSolar.