Answers:
This be below "Recommendations" on the below noted website:
" Men near mustaches may be aggravating their airborne allergies because allergens build up on the surface of the mustache."
http://griponarthritis.libraryonhealth.c...
it may comfort filter out some allergins but later again it might in recent times be a playground for them...
Shave it stale and see if your symptoms develop. If you can't factor w/your 'stache, I suggest wash it after you are outdoors if you own outdoor allergies.
I am really sorry but I go wrong to see the nouns between allergies and mustaches.