Flying on planes

Do any of you have trouble breathing on airplanes?  I know if I will have trouble as soon as they shut the door and I start breathing the nasty, recycled air.  On top of that you have an insane amount of dust and dust mites, smells from fellow passengers, cramped spaces, hot and stuffy when sitting on the tarmac in July, cabin pressure isn’t always great and fellow passengers hacking and coughing.

Sounds like a great environment for a severe asthmatic with severe allergies, right?  I’m going to be flying in the near future and have been thinking about how to make sure I stay “ok.”  I was thinking about maybe wearing a mask.  I’ve always heard nothing paper/cloth you buy works very well because it doesn’t seal to your face.  I emailed one of my lung docs who confirmed this for me in about 5 minutes.  Doesn’t seem worth it to go buy something, get stared at for 3 hrs and have it not be effective.  Probably my best bet is to drink lots of water, stay hydrated, and rinse my sinuses out as soon as I get to the hotel.  Does anyone have any good tips for avoiding bad breathing episodes on planes?