Falls from heights kill 140 children under age 15 each year in the United States, and seriously injure three million more, making falls are the leading cause of nonfatal injury for this age group. According to the American Academy of Pediatrics (AAP), falls are especially a problem for children living in multiple-story housing during the summer months, when windows are open and children are more likely to be playing on fire escapes, roofs and balconies. To keep kids safe, AAP recommends window guards [1] be installed on second story and higher windows. When choosing guards, install those that are operable in the event of emergencies like a house fire.
Links:
[1] http://www.moneypit.com/tip/childproof-window-guards