Discussion
In developing countries, traffic deaths are projected to be the third most important health problem by 2020, and a large proportion of these deaths involve motorcycles9 . Motorcycles are particularly dangerous vehicles. Motorcycle riders are at an increased risk of accident because the small size of the motorcycle makes them more prone than automobile drivers to experience serious injuries10. Assuming that a motorcyclist attains a riding license at the age of 17 and rides 13,500 km per year until retirement lifetime, the risk of death or serious injury approaches 100%11. It is clear that the use of helmets decreases the severity of injury and the probability of deaths, reducing health care costs12-14.