The medical community appears to be split on this.

Hand washing does help stop the spread of the common cold, many respiratory infections and viruses that cause diarrhea.

But in a Newsweek article, Arthur Reingold, head of epidemiology at the University of California, Berkeley, says there’s virtually no evidence that people can catch the flu virus via physical contact. He says people are more likely to catch the flu from breathing in microscopic particles exhaled by infected people.

Dr. Michael Osterholm, head of the University of Minnesota’s Center for Infectious Disease Research and Policy, notes that some animal studies confirm flu is transmitted through the air and not by physical contact.

Among those still promoting hand washing is the Center for Disease Control and Prevention’s Dr. Anne Schuchat. She supports hand washing because it protects against respiratory and intestinal diseases in general – and H1N1 does cause respiratory and intestinal problems.

What’s the take-home for businesses? First, hand-washing is effective in preventing some illnesses, so there’s no reason not to promote it.

Second, this points to the importance of sending sick employees home, and telling them to stay there until they’re well.

Third, the best step people can take starting next month is to get the H1N1 flu shot, when it becomes available.