To assess the effectiveness of seat belts and the risk of adverse effects a 12-month accident field study was carried out, which covered all non-minor injured belted occupants. The criteria laid down were as comprehensive as possible to permit assessment in each case of whether or not the restraint system had reduced or possibly increased injury severity. Seat belts were found to reduce the number of non-minor, non-fatal injured occupants to about 1/10 of the figure for unbelted occupants. Depending on the type and locality of the accident, this ratio varies from 1/6 to 1/28. The risk of death is cut to about 1/4. With respect to non-minor injured belted occupants, in 63% of the cases injury severity was reduced, while adverse effects can be reckoned with in less than 1.3% (95% level). With respect to accidents in which non-belted occupants suffer non-minor injuries, this risk is reduced to 0.2% (99% level), and in at least 96% of all cases reduction of injury severity can be assumed.
Abstract