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Physics shows why 20 seconds is right for hand-washing
Twenty seconds. That’s how long you need to wash your hands to remove germs, a new physics study confirms. Typical hand-washing guidelines—including those from the U.S. Centers for Disease Control and Prevention—advise scrubbing your hands for a minimum of 20 seconds. To assess that recommendation, researchers used a mathematical model to examine the key mechanics of hand-washing and […]