It’s a fall tradition: You grab your rake, gather the leaves into a big pile and watch the kids jump in. What's not to love?

The answer depends on whether your child has allergies, and also on what unexpected threats could be hiding under the leaves, especially if the pile isn't freshly raked. 

Related: 5 Ways to Get Your Home Ready for Fall

Mold

A type of fungus, mold doesn't just grow on bathroom walls or aged cheese. It also grows on fallen leaves, grasses and compost piles, according to the Asthma and Allergy Foundation of America.

“Children who have asthma and also have a mold allergy are at risk of having an asthma exacerbation from the mold exposure,” says Sarah A. Denny, MD, a pediatrician at Nationwide Children's Hospital in Columbus, Ohio. “Children who are allergic to mold should avoid raking leaves or playing in leaf piles, especially wet leaves.”

Mold, which travels through the air, also occasionally can infect the lungs, according to Normal Edelman, MD, senior consultant for scientific affairs at the American Lung Association. “However this is most likely when the lungs are abnormal as from bronchitis or bronchiectasis or when the immune system is impaired,” he says.

If you have a mold sensitivity and aren't able to stay away from leaves — which is the best option — Edelman recommends wearing an N95 respirator mask. You can find them at home improvement stores.

Critters

All manner of wildlife, such as spiders, beetles, caterpillars and wood frogs, will sometimes shelter among leaves, according to Mass Audubon, a nonprofit dedicated to preserving nature and wildlife in Massachusetts. Many are beneficial to gardens and can help with decomposition if you're starting a compost pile. But you probably don't want to surprise them, especially if they bite. Last spring in Lee County, Georgia, a copperhead snake bit a 16-year-old girl who stepped into a pile of leaves.

Ticks are another worry. These bugs can carry Lyme disease as well as a host of other diseases. Lurking among damp, shady leaves and brush, they lie in wait for a human or animal to bite, according to the Massachusetts Department and Health and Human Services.

Related: The Other Tick-Borne Diseases You Need to Beware

To discourage ticks and other unwanted creatures, don't let your leaf pile sit around like a lawn ornament. Bag and dispose of it as soon as possible. “I think the risk in freshly raked leaves would be minimal, but parents should take caution if leaf piles have been sitting for a while,” says Denny.

Sharp yard debris

“Children can be injured by sharp objects in leaf piles,” says Denny. Injuries can vary from cuts and bruises to corneal abrasions, she says. "Parents should make sure that all sticks, rocks, rakes, etc. have been removed before the children play in the leaf pile.”

A final caution

Don't let your children play in piles of leaves that have been swept into the street for the street sweeper to collect. “There are multiple reports of fatalities from children being run over by vehicles while the kids were in leaf piles,” says Denny. “Parents should also make sure that the leaf piles are in a safe place, away from the road, driveways and bodies of water.”

Related: 6 Surprising Ways You Can Get Poison Ivy

David Arv Bragi is a freelance journalist and marketing consultant. He has been writing about health and safety issues since the 1990s and currently lives in Portland, Oregon.