Many surfaces and objects you come in contact with every day are covered in germs -- but then again, so are you. "Ninety percent of you is composed of germ cells," said Philip Tierno, director of clinical microbiology and immunology at NYU and author of "The Secret Life of Germs."
He explained that while we are constantly in contact with germs, only a small minority will cause any harm.
"Of the 60,000 types of germs that people come in contact with on a daily basis ... only about 1 [percent] to 2 percent are potentially dangerous to normal people with normal immunity," he said.
That works out well for us, because pretty much any surface contains some of these microscopic organisms.
"There's very few surfaces that are truly clean," said Dr. Aaron Glatt, president and CEO of New Island Hospital in Bethpage, N.Y., and a spokesman for the Infectious Disease Society of America. "You're almost never going to culture something and not find some germs on it."