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American adults are liars, at least when it comes to washing their hands.

In a recent telephone survey, 91 percent of the subjects claimed they always washed their hands after using public restrooms. But, when researchers observed people leaving public restrooms, only 83 percent actually did so.

Only 75 percent of men washed their hands compared to 90 percent of women, the observations revealed.

The telephone survey also turned up several other results – some surprising, some not. While 83 percent said they washed their hands after using a home bathroom, 73 percent washed their hands after changing a diaper.

In contrast, low percentages of people wash their hands after petting a cat or dog (43 percent), after handling money (21 percent), after sneezing or coughing (32 percent).

"Only 24 percent of men and 39 percent of women say they always wash their hands after coughing or sneezing," said Brian Sansoni of the Soap and Detergent Association (SDA). "We have to do a better job here in stopping the spread of the germs that make us sick."

These results were released by the American Society for Microbiology (ASM) and the SDA to highlight National Clean Hands Week, which runs from Sept. 18 through the 24.

"Although many Americans are beginning to recognize the importance of washing their hands, we still need to reach many others," said Judy Daly, Secretary of the ASM. "Our message is clear: one of the most effective tools in preventing the spread of infection is literally at our fingertips."

Bacteria and viruses for the common cold and influenza spread much more often through hand contact than by airborne transmission through coughing or sneezing. Fifteen seconds of scrubbing with soap and water or a good rubbing with a hand sanitizer greatly reduce the amount of infective crud on your hands.

The study, done in four American cities, was carried out in August by Harris Interactive. The results were announced today.

Observers were stationed at Turner Field in Atlanta, the Museum of Science and Industry and the Shedd Aquarium in Chicago, Grand Central Station and Penn Station in New York, and the Ferry Terminal Farmers Market in San Francisco. They observed 3,206 men and 3,310 women. Here's some of what they saw:

Sports fans at Turner Field, particularly the guys, had the worst hand hygiene habits –only 74 percent of all patrons washed their hands (84 percent of the women and 63 percent of the men).

Results from the New York train stations provided the biggest gender split – 92 percent of the women washed their hands compared to only 64 percent of the men.

San Francisco turned out to be the most hygiene-conscious city in the study – 88 percent of the market goers washed their hands after using the facilities.

You might be wondering how the observations were handled. The observers were instructed to spend time combing their hair or putting on makeup and to rotate bathrooms every hour or so, and were only allowed to wash their hands 10 percent of the time.