make one’s hands safely clean after a medical examination requires thorough washing with soap and water for at least a full minute—a standard that is, in practical terms, all but unattainable for anyone dealing with lots of patients. It is a big part of the reason why every year some two million Americans pick up a serious infection in the hospital (and ninety thousand of them die of it). “The greatest difficulty,” Atul Gawande has written, “is getting clinicians like me to do the one thing that consistently halts the spread of infections: wash our hands.” A study at New York
