Summer is here, and with more people on the roads, the bicycle fatality and injury rate will climb. During the months of June through September, bicycle deaths double, according to the Insurance Institute for Highway Safety.

In 1998, some 758 bicyclists were killed in crashes with motor vehicles. Of these, 98% were not wearing a bike helmet. Bicyclists hospitalized with head injuries are 20 times as likely to die as those without. In fact, three quarters of fatalities are the result of head trauma.

But fatalities are not the only problem. Each year, more than 580,000 cyclists receive emergency room treatment, and 20,000 are admitted to the hospital. Head injuries are noted in 65,000 emergency room cases and 7,700 hospital admissions.

Riding a bicycle without a helmet -- or rollerblading without one, for that matter -- greatly increases the risk of sustaining a head injury in the event of a crash. Nonhelmeted riders are 14 times more likely to be involved in a fatal crash than those wearing a helmet.

In children, 90% of accidents are caused by falls from bikes rather than collisions with cars. The head is hit in 38% of bicycle accidents among children, rising to 55% among children 1-5 years old and 48% for children 5-10 years old.

Wearing bicycle helmets has been shown to reduce the risk of head injury by as much as 85%. Helmets also offer substantial protection to the forehead and midface, according to an important study reported 10 years ago in the New England Journal of Medicine. In this study, among 99 cyclists with serious brain injuries, only 4% were wearing helmets.

The highest bicycle-related death rates are among children 10 -14 years old. Universal use of bike helmets by children could prevent up to 45,000 head injuries a year, and up to 55,000 face and scalp injuries, the National Safe Kids Campaign maintains.

Cycling is great exercise, a fun pastime, and an environmentally friendly form of transportation. But it is not without hazards. Protect yourself and your children from serious injury this summer: wear a helmet!