Scrupuli

Our skin has bacteria living on it—and in it. Counting live cells in one square inch, forearms have been measured at 65,000, the abdomen at 260,000, underarms at 3,200,000, scalp at 6,500,000, and hands at 30,000,000.

Not all bacteria found on the skin cause illness. Some even set up house, living in permanent colonies attached to the deeper layers of our skin, without causing harm.

The surface of our skin also picks up and drops off visitors—germs, both bacteria and viruses—when we touch things. These visitors are often the ones which cause illness. Some die very quickly in the open air, but others can survive for long periods of time. They are also easy to wash away. This means that many illnesses can be prevented by hand washing.

It is especially easy to pick up and drop off germs when you touch moist surfaces—such as moist skin, food, and any damp or wet object.

You can prevent illness by washing hands before and after preparing food, and before eating. If you already have an illness caused by a germ, you can easily transfer it to your hands, and from there to anything or anyone you touch. Your bed, clothing, and other objects very close to you can also accumulate shed skin with germs on it. So anyone who touches you or these objects should wash their hands afterwards. (Clothing and bedding should also be washed regularly.)

Plain soap and water picks up germs without killing them, so they can be rinsed away. To be effective, you should rub all parts of your hands for at least 30 seconds, and then rinse thoroughly.

Soaps with germicide kill germs while the soap picks them up. They are used like plain soap.

Alcohol hand sanitizers kill germs by dissolving their outer parts. Use products containing 60–95% ethanol. Soiled hands can prevent the sanitizer from getting to all of the germs, so wash hands first if possible. Rub all parts of your hands until completely dry. Alcohol evaporates quickly, so apply enough (about one-half teaspoon) to keep your hands wet for at least 30 seconds.

The risk of alcohol fire is very low, but be sure to rub until completely dry, and keep wet hands away from sources of flame or static sparks.

Alcohol hand sanitizers with germicide work like plain alcohol sanitizers, but also continue to kill germs for a short time after your hands dry.

Soaps and sanitizers have been studied carefully to see which is best. The studies have found that not all germs are alike. Plain soap and germicide soap are about equally effective for preventing common illnesses such as colds and the flu. Washing hands followed by hand sanitizer is more effective than washing hands alone.

Some germs are naturally resistant to alcohol or to some germicides. If you are trying to prevent illness caused by a specific germ (such as hepatitis C) ask a doctor which germicide is most effective.

Some viruses are learning to adapt to germicides in soap. Some scientists are concerned that the use of germicides will cause these viruses to become common.

Use soaps and alcohols that contain skin conditioner, to prevent skin irritation and dryness.

To help children rub all parts of their hands for enough time, teach them to wash while they sing “Happy Birthday” twice.

For more information, see:

Guideline for Hand Hygiene in Health-Care Settings
http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5116a1.htm

Wikipedia: Stratum Corneum
http://en.wikipedia.org/wiki/Stratum_corneum