Mike,
I had a friend who managed a truce with such a person by blowing their nose in the most offensive, trummpeting fashion possible whenever the sneezer did their thing. The sneezer gave in first and came across tearfully to explain how the trumpet was affecting them. The agreement was that both parties would use handkerchiefs and do their best to moderate expulsions of whatever sort. ;-)
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1