How
long does it take you to wash your hands? If you
follow recommendations from the CDC, you're supposed to lather up and
scrub your hands for 20 seconds--the time it takes to sing "Happy
Birthday" twice.
Proper
handwashing is the single best way to prevent colds
and many other infectious diseases. The combination of 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.
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 Mayo Clinic study found no differences between these methods in
terms of removing bacteria from hands; other research suggests paper
towels are more effective. Whichever method you
use, the key is to make sure your hands are fully dry. Hands that remain
wet are more likely to transfer bacteria to and from the next surface
you touch.
Is hand sanitizer a good substitute?
Handwashing
is generally preferable, but alcohol-based hand
sanitizers are a convenient option when soap and water are not
available. They kill most bacteria and viruses on contact, but not
bacterial spores. Look for products with at least 60 percent alcohol
(ethanol and/or isopropanol). Rub about a dime-size amount
over all the surfaces of your fingers and hands until they are dry.
Dirt, food, and other grime on your hands make the alcohol in hand
sanitizers less effective, however, so if your hands are visibly dirty
or greasy, you're better off washing them.
What about antibacterial soaps?
We
don't recommend them for ordinary household use. Soaps
that contain antibacterial agents (most commonly, triclosan) kill or
inhibit bacteria, as well as help physically remove them. But there's
concern that such soaps contribute to the growing problem of bacterial
resistance, which is causing many essential antibiotics
to become ineffective. Also, though triclosan is not known to be hazardous to humans, studies in lab animals
have shown it to have hormone-disrupting effects. The FDA is reviewing its safety. Regular soap and water are all you need.
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