Consider it a professional hazard, but Bob Rother, manager of the Corporate Measurement Center of Excellence at Cummins’ Columbus Engine Plant (CEP), can tell you precisely how small a micron is. “A micron is almost indescribably small – it’s a millionth of a meter,” he says, holding his hands about shoulder-width apart. “So if I were to take a meter, which is about this far, and divide it into a million pieces, one piece would be a micron.