So Sneezing is Cathartic

You have been there.  For no reason at all you sneeze. And you continue to sneeze, for no apparent reason at all.  But you sneeze, and sneeze, and sneeze..

Why?  Well, according to Wikipedia, which is not an authoritative source:

"Sneezing is contagious and can spread disease.A sneeze (or sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs through the nose and mouth, usually caused by foreign particles irritating the nasal mucosa."

When we sneeze, those around us say things like "God Bless You" or "gesuntight

My personal observations about sneezes include that if someone has a nasal congestion, a sneeze, with a nose blow, may clear sinus passages, and diminish the need for  sneezes...

Or, the stimulus causing the sneeze may be dissipated after the sneezing starts, and  sneezing my diminish.

Personally, I am very sensitive to environmental factors that cause sinus congestion and sneezing... You may not believe it, but I have a friend who can attest to the fact that I can be in an area that causes nasal congestion, but can move a mere 10 yards, and the irritant is no longer felt, and the nasal congestion disappears.  Amazing. True.  And the sneezing stops...