Seat belt

A seat belt, also known as a safety belt or spelled seatbelt, is a vehicle safety device designed to secure the driver or a passenger of a vehicle against harmful movement that may result during a collision or a sudden stop. A seat belt reduces the likelihood of death or serious injury in a traffic collision by reducing the force of secondary impacts with interior strike hazards, by keeping occupants positioned correctly for maximum effectiveness of the airbag (if equipped), and by preventing occupants being ejected from the vehicle in a crash or if the vehicle rolls over. When in motion, the driver and passengers are traveling at the same speed as the vehicle. If the vehicle suddenly stops or crashes, the occupants continue at the same speed the vehicle was going before it stopped. A seatbelt applies an opposing force to the driver and passengers to prevent them from falling out or making contact with the interior of the car (especially preventing contact with, or going through, the windshield). Seatbelts are considered primary restraint systems (PRSs), because of their vital role in occupant safety. An analysis conducted in the United States in 1984 compared a variety of seat belt types alone and in combination with air bags. The range of fatality reduction for front seat passengers was broad, from 20% to 55%, as was the range of major injury, from 25% to 60%. More recently, the Centers for Disease Control and Prevention has summarized these data by stating "seat belts reduce serious crash-related injuries and deaths by about half." Most seatbelt malfunctions are a result of there being too much slack in the seatbelt at the time of the accident. It has been suggested that although seat belt usage reduces the probability of death in any given accident, mandatory seat belt laws have little or no effect on the overall number of traffic fatalities because seat belt usage also disincentivizes safe driving behaviors, thereby increasing the total number of accidents. This idea, known as compensating-behavior theory, is not supported by the evidence.