Every year, 40 to 50 children are admitted to Harborview Medical Center after falling from an open window, says Dr. Brian Johnston, the hospital’s chief of pediatrics.

Harborview’s Injury Prevention & Research Center estimates that over 85% percent of children who fall through windows first fall through a screen.

Insect screens are designed to keep bugs out, but not to keep children in, says Johnston, a professor of pediatrics at the University of Washington School of Medicine. Simple window stops can provide a safe solution.

“When we’re using windows stop, an important number to remember is 4 inches. We want to allow a window to open up to 4 inches for ventilation, but windows that are more than 4  inches open allow a toddler or another child to pass through.”

In an instructional video, Johnston demonstrates how to install and use two common window stops.