Students are headed back to school this week and along with the backpacks and new lessons comes recess at playgrounds for young scholars.
Kids love to climb, slide, play and swing and some parents worry about the cleanliness of playground equipment.
So, "Good Morning America" investigated playground cleanliness across the nation by collecting 60 samples at public playgrounds. The samples were tested to determine which playground was the cleanest and which had the most germs.
Of those samples, 59 had evidence of bacteria or mold that could make children sick tests showed.
"GMA" tested 12 playgrounds in four cities including: Washington, D.C., and suburban Virginia and Maryland; two in New York City; and at three parks in Chicago.
The places children are more likely to touch were swabbed and samples were collected from a variety of places such as swings, slides and seesaws in Washington, D.C. Monkey bars and jungle gyms were swabbed in New York, while steering wheels and tire swings were tested in Chicago.
Finally, in Phoenix baby swings and a rock climbing wall were tested.
All the swabs were sent to a lab at New York University School of Medicine where Philip Tierno gave the results.
"All representatives had evidence of fecal flora," he said.
That means human feces was present everywhere and where there is feces, a chance of illness exists.
Salmonella, shigella, hepatitis A and a norovirus also were found in some of the samples.
Thirty samples tested contained E.coli. In fact, 11 of Chicago's 15 samples came back with bacteria.
And children can ingest all this bacteria if they put their hands in their mouths.
"GMA" also found bacteria that came from people's skin and sinuses.
At Encanto Park in Phoenix, a sample contained staph aureus, which can cause diseases like pneumonia. And on a baby swing seat at Chicago's Armour Square Park, group-a beta strep was found. It can lead to strep throat and other illnesses.
Tierno said the testing uncovered so many germs because of the time of year. Combining hot, humid weather and lots of visitors is a recipe for growth, experts say.
Of all the cities tested, Chicago's playgrounds had the heaviest bacteria growth followed by Phoenix, according to the NYU analysis.
New York City's Battery Park had the fewest germs.
And though the swabbing turned up a variety of germs, Tierno said many of them won't harm people.
"Most don't hurt us, but it's the few that do hurt us that justify our concern," he said.
One way to protect children from germs and illness is by making them wash their hands, especially before eating.
Also, nature helps get rid of germs. The sun's ultraviolet light kills bacteria. So, equipment that sits in the shade are more likely to have bacteria.
The parks also are trying to keep themselves clean.
The parks departments for the playgrounds tested said they take playground safety very seriously.
Some cities, like New York, said they clean playground equipment when it's visibly dirty. In Chicago, Washington, D.C., and Fairfax, Va., the equipment is cleaned on a regular schedule.
And Phoenix said it is looking into putting hand-sanitizing products and dispensers on playground sites.