A new study comparing kids in the U.S. and the Phillipines has confirmed that growing up in a too-clean environment can boost inflammation levels, which in turn may increase the risk of heart disease and other chronic ills in adulthood. So is it still a good idea to get our kids to wash their hands all the time to prevent the spread of H1N1 and other cold and flu germs?

Coincidentally, this week two housemates familiar with my book Good Germs, Bad Germs emailed me with the hope of resolving just this debate over H1N1 and hand washing. Their household includes a 5-year-old as well as an adult with a donated kidney.

Housemate #1 had been urging the five-year-old to wash her hands frequently "to prevent the spread of too many germs," including H1N1. Housemate #2 countered that the germs that ended up on the child's hand were good for her--helping her build up resistance to disease.

The title of Good Germs, Bad Germs goes right to the heart of their question. So I'm glad to offer my two cents, based on the research of immunologists and infectious disease specialists.It's true that exposure to "germs" (i.e. viruses and bacteria) is necessary to strengthen and balance the developing immune system. This appears to be most important in early childhood.

Fortunately, this exposure doesn't have to involve the kind of germs that make you sick. In fact, the vast majority of germs in our environment are harmless. They're in our water, on our pets, in good, old fashioned dirt, everywhere. And that turns out to be a very good thing. Our world and our bodies could not functional normally without them.

By contrast, only a tiny minority of the viruses and bacteria we encounter each day make their "living" by causing disease. That said, this rogue's gallery includes some nasty characters, with the H1N1 influenza virus now among them. Such "bad germs" are definitely worth avoiding.

Bottom line: With H1N1 circulating widely in our communities, the experts agree that it's definitely a good idea for everyone to wash hands frequently or use an alcohol-gel sanitizer.

This is most important after being around other people who might be infected. Someone carrying H1N1 touches something (school desk, office keyboard, doorknob, etc.) and deposits the virus. You touch that something and then touch your eyes, nose, or mouth and, bingo, that virus has found a new home.  

Frequent hand washing is even more important if you live with anyone with an immune-compromising condition. This includes organ recipients, who must take powerful immune-suppressing drugs to prevent their bodies from rejecting the donated organ. 

Science journalist Jessica Snyder Sachs is the author of Good Germs, Bad Germs: Health and Survival in a Bacterial World. Got a question or comment about swine flu? Post it here. Throughout the flu season, Jessica will be answering your questions on all things influenza.