Eventually Harv got up and tied a strip of white Nanobar around his face. 
The spot over his mouth immediately began turning gray. He ejected used 
cartridges from his mite gun and inserted new ones. It was shaped like a gun, 
but it sucked air in instead of shooting things out. You loaded it with 
drum-shaped cartridges filled with accordion-pleated paper. When you turned it 
on, it made a little whooshing noise as it
sucked air—and hopefully mites—through the paper. The mites got 
stuck in there. "Gotta go," he said, goosing the trigger on the gun a couple 
of times. "Never know what I might find." Then he headed for the exit, 
leaving black toner footprints on the floor, which were scoured away by the 
swirling air currents in his wake, as if he had never passed that way.