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Abstract
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On the need for helmet-wearing by occupants of automobiles.
Man in the last third of the twentieth century finds it increasingly convenient to travel at high speeds in pieces of fairly heavy machinery. When crashes occur, the injuries involved are often the results of amounts of energy far in excess of human tolerance. History suggests that accidents will continue to be with us and that our mission as physicians is to try to attenuate the forces imposed.
All of us are familiar with the principle of the primary collision and the secondary collision. Injuries occur in the secondary collision, that of the occupant with the adjacent structures of the machinery or vehicle in which he is packaged. Better packaging of the occupant, therefore, seems to be a logical and a sensible approach.
If we interpret national statistics personally, each of us has during his lifetime a one-in-fifty chance of being killed in an automobile crash, a one-in-fourteen chance of being permanently disabled, and is paying a penny a mile for his and other people's automobile accidents. A car has one chance in thirty of being involved in an injury-producing accident each year, or, taken over ten years, one chance in three.
The nature of the injury is directly related to the area over which a force or pressure acts. As the area becomes smaller, the pressure becomes larger. For example, the effects of a 200-pound force on a four square inch area of the skull is spread to fifty pounds per square inch. The same 200-pound force against a fifth of an inch of skull is equal to a thousand pounds per square inch. The purpose of a protective hat, then, is to take the first impact of a localized force on a small area, spread it over a wide area, and at the same time increase the stopping distance of the head, the object to be protected, by a scant inch or a fraction thereof.
This paper discusses the design and testing of helmets designed for automobile occupants. Photographs of normal and dress-style helmets for men and women are provided. |