Hay fever causes problems with wearing the oxygen mask.
Edit: Downvote me if you like, but that's the reason I was given when I asked an Air Force pilot.
Edit: Downvote me if you like, but that's the reason I was given when I asked an Air Force pilot.
Picture this:
It's time to go fly. The alarm is going off, and you need to get in your jet. Boogers are streaming down your face, and you are experiencing sneezing fits that have you bent over with your eyes closing and tearing up. You can put on a mask with nice clean air, but it'll take an hour before you are in condition to fly. Sitting there on the runway waiting for your allergies to stop acting up is not acceptable.
You'll also need a HEPA filter to filter out pollen, just a dust filter won't do it.
Maybe the case could be made for fighter pilots (though I still think it's a non-issue for 99% of people with seasonal allergies), but what's the excuse for disqualifying for all aircraft? Airline pilots can have allergies and fly. How is that much different from a heavy cargo plane?
1. Deployed environments are often less than pretty. There's pretty much no comparison between a peacetime US/Europe life and wartime, even at airbases.
2. In the military, aircrews are expected to go down behind enemy lines, regardless of how often it happens against terrorist groups. They want to maximize your probability of survival after the crash/shootdown. Medical preconditions of any kind don't really help that.
Non-pilot millitary personnel get deployed and are on the ground in war zones 10x more than pilots (especially in the army) and they aren't disqualified for having allergies.
It's just not a big deal except in the most egregious of hay fever cases
Source: Marine Pilot.