Lylah Jones, left, 3, and her sister Violet Thamarus, 5, of New Philadelphia, Pa., enjoy the spring weather in Port Carbon, Pa., on Tuesday, April 19, 2016. (Andy Matsko/The Republican-Herald via Associated Press)

Playground concussions are on the rise, according to a new government study, and monkey bars and swings are most often involved.

Most injuries studied were mild, but all concussions are potentially serious, and the researchers say the trend raises public health and safety concerns.

The Centers for Disease Control and Prevention study examined national 2001-2013 data on playground injuries to children ages 14 and younger who received emergency-room treatment. Of almost 215,000 children on average treated yearly, almost 10 percent — about 21,000 annually — had traumatic brain injuries including concussions. Only nonfatal injuries were included.

Here are some key findings, published online Monday in Pediatrics:

In 2005, 23 out of 100,000 children had traumatic brain injuries, a rate that jumped to 48 out of 100,000 in 2013. The rate declined in the previous years but increased steadily after that. By 2013, the annual total was almost 30,000 children treated for these brain injuries.

The rise may mean parents are becoming increasingly aware of the potential seriousness of concussions and the need for treatment. It’s also possible that more children are using playground equipment, the researchers said.

Only 3 percent of children with concussions were hospitalized or transferred elsewhere for additional treatment; 95 percent were sent home after ER treatment. Half of the head injuries were in children 5 to 9, and injuries were more common in boys. Symptoms weren’t listed, but signs of concussions after a blow to the head can include headaches, dizziness, confusion, nausea and vomiting.

Concussions are a type of traumatic brain injury typically resulting from a blow to the head that jostles the brain and temporarily disrupts brain function. Symptoms can last days or weeks, and although most children completely recover, repeated blows to the head have been linked with brain damage — most notably in some retired National Football League players.

Jeneita Bell, a CDC brain injury specialist who co-wrote the study, said the results highlight “that sports is not the only important cause of concussions and other traumatic brain injuries for children.”

The researchers said adult supervision is key to helping prevent these injuries. They also recommend checking to make sure that playground equipment is in good condition and that ground surfaces use soft material including wood chips or sand, rather than concrete.

Bell also recommends reading playground signs “and using playground equipment that is right for your child’s age.”

— Associated Press