Ever wonder just where your nurse’s hands have been? A new study has bad news for you.

Nurses — and doctors as well — aren’t practice basic hand hygiene unless they’re being watched, meaning that you’re far more at risk of contracting a deadly illness than you realize, according to an Association for Professionals in Infection Control statement.

Washing hands is one of the most effective ways hospitals can avoid transmitting illness throughout their facilities. But the study found that unless medical professionals were being monitored, they didn’t wash their hands nearly as much and risk transmitting germs to other people.

The findings suggest that human behavior, and not better technology, is the true key to reducing deaths and debilitating illnesses at hospital facilities. Researchers came to their conclusions by having nurses monitored when they knew they were being watched, and when they didn’t realize it.

“The level of hand hygiene compliance when staff did not know they were being watched was surprising,” said Maricris Niles, MA, infection prevention analyst, Santa Clara Valley Medical Center, California. “This study demonstrated to us that hand hygiene observations are influenced by the Hawthorne Effect and that unknown observers should be used to get the most accurate hand hygiene data.”

“This was not a result that we expected to see,” said Nancy Johnson, MSN, CIC, infection prevention manager, Santa Clara Valley Medical Center. “We have rolled out many changes as a result, including an organization-wide, hand hygiene improvement plan that is actively supported by our leadership team.”