If the situation continues, the person may faint, or even die. In order prevent any mishap, the brain induces ‘violent’ sneezing, thereby splashes away all the droplets, and clears the breathing holes.
If water droplets keep on ‘oozing’ into the breathing holes repeatedly, then, sneezing too becomes continuous. Once the passages are cleared, sneezing stops. We should not suppress sneezing for any reason.
In rooms that are air-conditioned, the moisture from the air is often ‘sucked out’ (dehydrated) by the air-conditioner.
Therefore, a person working in such an environment would breath only dry air. However, if the person comes out of the ‘dry’ room to a place where the air contains a lots of moisture (i.e., high relative humidity, RH), the latter would enter into the lungs while inspiration and gets condensed into droplets.
Thus, the person may start sneezing continuously until the moisture contents of the lung environment gets even with the external situation.
At times, if dust or any other minute particles that pass through the nose get settled in the alveoli, they too will induce sneezing, for that alone appears to be the best method for their eliminations.
See Cough, Asthma, Hyperhidrosis. My book entitled “Asthma, Bronchitis, Cough Sneezing and Sweating” (2001) contains elaborate information on this subject.