Accidental injury is the leading cause of death among children ages one to 14 in the U.S., according to a study by Safe Kids USA. One of the top risks for young children is drowning—and this risk is especially high if the child’s family owns a swimming pool.

Studies by safety groups have shown that at the time of most drowning incidents, a parent or a caregiver was supervising the child at the house, but the child got out of the adult’s sight—sometimes for just a few minutes.

Adult supervision is the first line of defense against children’s drowning death or injury, but the National Drowning Prevention Alliance says that “layers of protection” are vital. Swimming pool owners need several barriers to ensure the safety of children in the proximity. Another important “layer of protection” is an isolation fence that forms a barrier around the swimming pool. Studies have shown that isolation fences, used properly, can prevent up to 90 percent of drownings among children under age four.

What are the characteristics of effective isolation fences?

First, fencing around the property might keep neighbors’ kids away from the pool, but for the safety of children in the home, there must be a fence completely surrounding the swimming pool, isolating it from the house.

The fence should be at least four feet high and have no footholds or handholds a child could use for climbing. Vertical fence slats must be less than four inches apart so even a small child cannot squeeze through.

Gates must be self-closing and self-latching. Magnetically triggered latches have been shown to be the safest and most reliable because, unlike gravity latches, they do not mechanically resist closure. The latch should be high enough to be out of the reach of a child. Inspect swimming pool gates at least once a day to be sure they self-close and self-latch every time.

Never prop open the gate for any reason. Tell visitors and workers not to prop open the swimming pool gate. Many reports of toddler drownings cite a propped-open gate as a contributing factor.