According to the National Highway Traffic Safety Administration (NHTSA), 32,598 people were killed in motor vehicle traffic crashes in 2002. Among car occupants older than four, safety belts saved an estimated 14,164 lives that year. The NHTSA estimates that if all passenger vehicle occupants older than four wore safety belts, an additional 7,153 lives could have been saved.

It is clear from these statistics that a seatbelt can save the life of the person wearing it. But, could it save someone else’s life too? A study published in the January 21, 2004 issue of the Journal of American Medical Association looked at the effect of wearing seatbelts on all occupants in car crashes.

About the study

  • Using the NHTSA’s Fatality Analysis Reporting System, researchers collected data on crashes that occurred between 1988 and 2000. The study subjects were referred to as targets and were grouped in pairs.

Researchers divided the targets into three categories:

  • Front-seat target pair: the target pair was seated in the front seats of the same car. The passenger (restrained by a seatbelt or unrestrained) was seated in the back seat of the same car directly behind a target. The study examined more than 60,000 front-seat targets.
  • Rear-seat target pair: the target pair was seated in the back seat of the same car. The front-seat passenger or driver (restrained or unrestrained) was seated directly in front of a target in the same car. Of the 5,278 rear-seat targets, all of the left rear targets had a driver in front of them and almost all (90%) of the right rear targets had a passenger in front of them.
  • Side-seat target pair: both members of the target pair were either seated on the right side of the same car (one in the front and one in the back) or both were seated on the left side of the same car (one in the front and one in the back). The passenger or driver (restrained or unrestrained) was seated in the same row (front or rear) as the target.

The researches excluded convertibles, light trucks, vans, minivans, and sports utility vehicles in their analysis. In addition, the data was adjusted for several factors, including the presence of air bags.

The findings

The researchers found that the risk of death for a restrained target in the front seat was increased by 20% when a passenger in the back seat was unrestrained. For a target in the back seat, (restrained or unrestrained), the risk of death was increased by 22% when the front passenger was not wearing a seatbelt. The risk of death for a restrained side-seat target increased by 15% when the passenger on the other side of the car was not wearing a seatbelt.

The authors estimate that use of seatbelts by passengers in the back seat may prevent about one in six deaths of front seat passengers wearing seatbelts and use of seatbelts by front seat occupants may similarly reduce the risk of death for all rear seat passengers.

These findings make sense when you realize that, during a serious car crash, anything that is not bolted down or securely tethered becomes a dangerous projectile. Flying human bodies can apparently be quite lethal.

How does this affect you?

The first seat belt law came into effect in 1984 in New York. Since then, 49 states and the District of Columbia have enacted seatbelt laws (New Hampshire is the only state that hasn’t). With all the research available, you shouldn’t need a law to tell you to buckle up to reduce your risk. And, this study shows that it is not enough just to buckle yourself in. If you want to reduce your risk, ask others in the car to buckle up too.