Once school lets out for summer recess, many children will spend their days at city playgrounds, but some parents are concerned about playground safety.

The Centers for Disease Control and Prevention says falls are the No. 1 cause of non-fatal injury for children from toddlers to teens.

According to the CDC, about 8,000 children are treated in U.S. emergency rooms for fall-related injuries every day.

That figure adds up to almost 2.8 million kids being treated every year.

The National Program for Playground Safety says adult supervision is the key to preventing many of these injuries. They say adults can look out for potential hazards and facilitate play when it's necessary.

Safety experts also say parents should make sure kids are playing on age-appropriate equipment.