Summer has arrived. And for all its pleasant, warm-weather pastimes--pool parties, barbeques, bicycling, and more--an emergency department near you is feeling the usual seasonal spike in children's unintended injuries and deaths. No wonder summer is known in the medical business as "trauma season."

Childhood deaths from unintentional injuries, reassuringly, are rare. But add up the pain of broken bones (plus the angst of a childhood summer spent in a cast), parents' time taken off from work to nurse an injured kid, medical bills--not to mention the use of ER resources--and the possibility of a lasting disability from, say, a brain injury sustained in a bicycle accident, and you've got a costly impact on families and society.

Marie Lozon, division director of pediatric emergency medicine at the University of Michigan Health System, tends not only to the young patients who are rushed through the doors of her emergency department but also to shocked parents. "Every day I hear, 'I just turned my back for a second,'" she says. A brief lapse in supervision is often a critical factor in kids' visits to the ER during trauma season.

Between conversations with Lozon and another expert, Chrissy Cianflone, director of program operations at Safe Kids USA, U.S. News has compiled a list of some common trauma-season causes of unintentional injury to kids--and simple ways to avert such disasters:

1. DROWNING

Lack of adult supervision and drowning go hand in hand. In summer, kids drown at nearly twice the rate that's typical for the rest of the year--reflecting a steeper summertime increase than exists for any other kind of unintentional injury to kids.

The most basic, common-sense advice to prevent children from drowning is to have an adult watching the water at all times. Sounds obvious, like something any parent would do instinctively, but Cianflone says a kid drowning is usually "a matter of everybody was watching, but nobody was watching." The solution, she says: Having a designated adult with his or her eyes on the water at all times and the ability to jump in quickly.

Both Lozon and Cianflone recommend that backyard pools be surrounded by fencing on all sides and have a self-locking gate so kids cannot wander out the back door and jump into the pool. Children who go swimming in lakes, oceans, and rivers need life jackets, says Cianflone, and parents need to model the behavior for young kids.

2. BIKE ACCIDENTS

Deaths related to biking increase about 45 percent in summer, compared with other times of the year. Certainly, riding around in the warm weather is a favorite childhood pastime, but doing so without wearing a properly fitted helmet could be asking for trouble.

Cianflone recommends buying a helmet that meets the standards of the Consumer Product Safety Commission, which should be evident by a CPSC sticker inside the helmet. Bell Sports, she adds, makes a helmet for kids called True Fit that requires only one step to adjust the helmet for a proper fit.

3. MOTOR VEHICLE-RELATED ACCIDENTS

Motor vehicle crashes are the leading cause of death among kids ages 3-14 in the U.S. In 2005, according to the U.S. Centers for Disease Control and Prevention, 1,335 passengers ages 14 and younger died and 184,000 were injured in motor vehicle crashes. That's a daily average of four deaths and 504 injuries.

A number of factors are involved, including high-traffic holidays--in particular, Memorial Day, the Fourth of July, and Labor Day--an excess of drinking, and parents who don't bring their children's car seats on vacation.

A properly fitted car or booster seat is essential to preventing a child's injury or death in an accident, says Cianflone. (Safe driving, obviously, is as well.) Size matters--only kids who are at least 4-foot-9 and weigh 80 to 100 pounds can safely wear a seat belt. It is estimated that 73 percent of car seats are either installed wrong or aren't used correctly.

Speed and collisions aren't the only hazards with motor vehicles. Between 1998 and 2004, an annual average of 33 children died of heat stroke because they were left in an unattended vehicle, Cianflone says. Sometimes a child playing hide-and-seek or mimicking her parents will pull down the back seat and climb into the trunk. In other instances, a parent might leave a child in the car to run a quick errand, or they might simply forget their child in the back seat.

Recreational vehicles and riding lawn mowers also come out of the garage this time of year, and they pose their own dangers. They have a high center of gravity and are easy to tip over, she explains. Plus, the rider is not protected by a shell, as they would be in a car. Lozon sees numerous head and neck fractures, and kids can be crushed by an ATV rolling over them.

4. PEDESTRIAN ACCIDENTS

Kids are out and about more often in the summer, frequently unsupervised, and that contributes to a 16 percent spike in child pedestrian deaths this time of year. Again, a child's level of development plays a role in their risk: Research suggests that before age 10, children are particularly impulsive and also cannot judge speed, spatial relationships, or distance very well.