Sneezing is caused by something irritating your nasal passages such as pollen, dust, cold weather etc.
When you have uncontrollable sneezing you're likely just in the vicinity of the allergens or other irritants and when you get away from the allergens or irritants the uncontrollable sneezing should stop.
There could also be other health issues that cause you to sneeze uncontrollably which you should see your doctor or an allergist about.
That is if the uncontrollable sneezing continues and doesn't stop or seems to get worse then a doctors visit would be recommended.
There are times when I get uncontrollable sneezing attacks and after the allergen goes away or the dust goes away etc then the sneezing stops.
I usually use some nasal spray to help clear my nasal passages of allergens and that seems to help when I have uncontrollable sneezing.
I would also recommend using an air purifier to help get rid of the dust in your home.