Pea Gravel

There are a lot of disadvantages to pea gravel: Kids throw it, get it in their shoes, scoop it onto slides and other play equipment, and sometimes even put it in their mouths. If you drop eyeglasses, small toys, or keys in pea gravel, you may never find them again. Pea gravel is also prone to get slimy and invite animal waste.

Wood Chips

Wood chips look pretty for the first few months, but then they start to fade, disintegrate, and eventually become dusty, gray clots. Wood chips have to be replaced quite often, especially in regions where there is a lot of rain and cold weather. Wood attracts bees and other insects and can harbor a number of potential hazards. Like anything loose, kids throw wood chips, put them in their mouths, and track them home in their shoes or on their clothing.

Sand

As long as it’s dry, sand makes for a soft landing. But when it’s wet, it can be hard as a rock. Like gravel, kids pick up sand and throw it, eat it, and track it everywhere. You never know what’s in the sand; it could have industrial waste, mercury, lead, and crystalline silica (like fiberglass). Plus, sometimes a sand playground surface can be a giant litter box.