In the controversy over air bag safety, it's easy to forget the humble seat belt. But when you're talking protection, belts beat bags by a wide margin.

In the car crash that killed Princess Diana in 1997, three of the four passengers died. The sole survivor—bodyguard Trevor Rees-Jones—was the only passenger wearing a seat belt.

Buckling Up—a Simple Act With Major Payback

Diana's tragic crash illustrates what safety experts have been saying for years about the value of wearing seat belts. Studies from the National Highway Traffic Safety Administration (NHTSA) show that "the lap and shoulder belt, used properly, reduces the risk of fatal injury to front seat passenger car occupants by 45% and the risk of serious injury by 50%."

In plain language, if you're not buckled up in a crash, you're twice as likely to die or suffer a serious injury. Yet there's still a small, hard-core group of non-seat belt users who simply don't think about being killed or injured.

"Fastening a seat belt is the most significant driving-related behavior change you can make to extend your life. It's the best weapon against a drunk, tired, or aggressive driver," according to James L. Nichols, the director of NHTSA's Office of Research and Traffic Safety.

What Happens to Your Body in a Collision?

In a motor vehicle collision, medical experts have identified three impacts:

  • The vehicle strikes another object, such as a tree.
  • The "human impact" occurs. Unbelted occupants slam into hard, unforgiving parts of the vehicle's interior—the steering wheel, the windshield, the roof—or into other occupants.
  • The final impact takes place within your body as the internal organs smash against other body parts—ie, the heart hitting the sternum, the brain hitting the skull, the lungs hitting the ribs.

Unbelted occupants can also be ejected from the vehicle, which is one of the most injurious events that happens in a crash.

Here's what seat belts do for you in a collision:

  • Hold you securely, taking advantage of the vehicle's own protective crushing effect as it absorbs energy in the first impact.
  • Distribute the force of the human impact across the strong parts of the body. Your body hits the belt rather than the steering wheel, windshield, or other hard parts of the interior.
  • Prevent occupants from colliding with each other.
  • Help the driver maintain control, decreasing the possibility of an additional collision.
  • Prevent occupants from being ejected.

Air Bags: Strictly a Supplement to Seat Belts

Although seat belts are your main defense against the impact of a crash, air bags do provide a marginal reduction in fatality risk. For belted drivers, air bags provide a 9% reduction in the risk of death in a crash. If you're not buckled up, air bags reduce your risk of death by 13%, since you have lost your 45%-50% seat belt injury protection.

Air bags inflate with tremendous force in a crash and have actually caused injury and even death on occasion, mostly to children and shorter adults. To minimize the risk from air bags, it's crucial for occupants to use seat belts or child restraints properly and to be positioned as far away from the air bag as possible (while still maintaining control of the car if you're the driver).

While there is still controversy surrounding air bags, there's no debating the effectiveness of seat belts. A properly worn belt even protects you against the injuries that may be caused by air bags!

The Long (and Short) Arm of the Law

Why, you ask, doesn't everyone buckle up all the time? According to the 2006 National Occupant Use Survey, 81% of Americans wear their seat belts, with ranges from 63.5% in Wyoming to 96.3% in Washington.

One reason for usage rate differences is uneven enforcement. There are seat belt laws in all of the states, but 32 states allow only "secondary" enforcement, meaning a citation can be written only after an officer stops you for another traffic violation. In stricter "primary" enforcement states, sometimes called "Click It or Ticket," officers can write tickets for unbuckled occupants just as they would for running a red light or speeding.

Excuses, Excuses

Most people who buckle up do it to avoid injury. Yet the people who don't wear seat belts also have some very "logical" reasons, but these reasons don't take the following factors into account:

"Logical" ReasonsReality
  • I'm just going to the store.
  • I'm a good driver.
  • I'm not in the habit of wearing them.
  • They don't feel comfortable.
  • It's nobody's business but my own.
  • I'm afraid of being trapped in a fire or under water.
  • Many deadly crashes take place close to home.
  • Accidents are often caused by the other driver.
  • Unbelted occupants frequently injure other occupants.
  • Unbelted drivers have less chance to control the vehicle after the impact.
  • Taxpayers pay the majority of medical costs for crash victims.
  • The vast majority of fatalities result from the force of impact, not from being trapped.
  • Children are less likely to be buckled up if adults are not.

Joseph Blansfield, trauma coordinator at Boston Medical Center in Boston Massachusetts, tells non-wearers: "Don't be a fool. You can be the best driver in the world, but the guy coming around the corner could be drunk out of his mind or have bad eyesight and plow right into you."

Racecar Drivers Do It

"Hey, I'm a great driver…I can avoid bad news coming down the road."

If you feel that way, racecar driver Jeff Burton begs to differ. Burton, who drives at speeds up to 200 miles per hour for NASCAR's Ford Team, was in a serious passenger car crash but was wearing a belt and wasn't seriously injured.

"People who have never been in a wreck need to listen to those who have and who drive for a living," says Burton. "We know what your body goes through and how hard the impacts are. I can't imagine getting hit at 30 miles per hour without wearing a seat belt. If you can't avoid an accident, the next best thing is to have your seat belt on."

You've heard it before, because it's true: Better safe than sorry.