Handwashing is the single best way to prevent colds and many other infectious diseases—as long as you do it right. Soap and water, along with the friction of rubbing your hands together, loosens dirt and creates a slippery surface so germs slide off.
You should wash your hands often, before and after eating or preparing food (particularly raw meat, fish, and eggs), after using the toilet, after blowing your nose, after changing a diaper, after playing with pets or cleaning up their waste, before and after touching someone who is sick or treating a wound, before putting in contact lenses, and after gardening.
How long should it take you to wash your hands?
If you follow recommendations from the Centers for Disease Control and Prevention (CDC), you’re supposed to lather up and rub all surfaces of your hands together for 20 seconds—the time it takes to sing “Happy Birthday” twice. According to the World Health Organization, the whole process, from washing to drying your hands, should take 40 to 60 seconds.
Does the water temperature matter?
There’s little research, but two studies suggest that water temperature has no significant effect on reducing bacteria under normal handwashing conditions. A downside to hot water is that it can irritate skin. Hotter water does cut through oil on your hands faster, but cooler water will also do the job.
How should you dry your hands?
Drying your hands reduces bacteria levels further, but it’s debatable whether using paper or cloth towels or a warm-air dryer is best. A study from the Mayo Clinic in 2000 found no differences between these methods in terms of removing bacteria from hands; other research suggests paper towels are more effective. If you use a dryer, keeping your hands still removes more bacteria than rubbing them together.