When you use an action to throw a handful of the dust into the air, you and each creature that needs to breathe within 30 feet of you must succeed on a DC 15 Constitution saving throw or become unable to breathe while sneezing uncontrollably. A creature affected in this way is incapacitated and suffocating.
As long as it is conscious, a creature can repeat the saving throw at the end of each of its turns, ending the effect on it on a success.
The lesser restoration spell can also end the effect on a creature.