"Wow. People sure are coming up with interesting ways of avoiding the question."

My response was a real request for information- if this is a pure utility test, I would select the dust specks. If this were done to a complex, functioning society, adding dust specks into everyone's eyes would disrupt a great deal of important stuff- someone would almost certainly get killed in an accident due to the distraction, even on a planet with only 10^15 people and not 3^^^^3.