On an icy Nebraska road in January 2005, a sports utility vehicle went out of control, tumbling over and over down a roadside ditch. The driver and a front-seat passenger -- both wearing seat belts -- suffered non-life-threatening injuries. But Derek Kieper, a 21-year-old student at the University of Nebraska, was thrown from the back seat of the vehicle and killed. Ironically, less than four months earlier, Kieper had written an editorial for the school paper decrying seat belt laws as an infringement on personal liberty. "There seems to be a die-hard group of non-wearers out there who simply do not wish to buckle up no matter what the government does. I belong to this group," wrote Kieper in his editorial.

But preventing someone from being ejected from the car during an accident is what seat belts do best. In a Department of Transportation study of fatal crashes, people who weren't wearing seat belts were 30 times more likely to be thrown from the vehicle than those who were belted in. And being "thrown clear" means that you are 25 times more likely to die or be seriously injured than if you had remained inside the vehicle, according to James Madison University.

To understand how seat belts work, it helps to take a look at what happens in a car crash. Engineers at The National Highway Traffic Safety Administration (NHTSA) conduct crash tests on all kinds of cars in all kinds of conditions. What they have found is that each crash consists of three separate collisions.

Picture an accident happening in slow motion: First, there's the car's impact with whatever it hits. In the time it takes for the car to crumple and come to a stop, the passengers inside are still traveling at the same speed the car was going before the crash. In the absence of a seat belt the passengers keep hurtling forward after the car stops until they collide with some part of the vehicle -- or other passengers. People in the back seat can become human projectiles, hitting passengers in the front seat. Even after the passengers' bodies have come to a stop, there is a third collision as their internal organs slam against their bones or other organs.

According to the NHTSA, this internal collision is often the cause of serious injury or death. Think of a person's head colliding with the dashboard -- while there might be a bruise or a bump on the outside, it's the brain colliding with the inside of the skull that can cause the real damage.

Seat belts are designed not only to keep you from being thrown from the car, but also to absorb the impact of a crash where your body can withstand it best -- in the bones of your hips, shoulders, and chest, according to the NHTSA. Seat belts also stretch slightly so your body doesn't stop as abruptly, and they prevent you from colliding with a part of the car or another person. A report from the University of Washington found that when used together, automatic shoulder harnesses and lap belts reduce your risk of death in a car crash by 86 percent. James Madison University also notes that seat belts, when used properly, reduce the number of serious traffic injuries by 50 percent.

One caution: Using a shoulder belt without a lap belt only reduces your risk of death by about a third, and can actually increase the likelihood of chest or abdominal injuries, so always use both.

Not by a long shot. In fact, being too close to an air bag when it deploys can be dangerous or even fatal, especially for small children. Seat belts keep you far enough away from the air bag so that it will cushion you, not injure you. Front and passenger-side air bags only protect you in a head-on collision, so if you have a side-impact collision, or if your car rolls over, a seat belt is your only protection. (Side and curtain air bags, available in some newer cars, are located in the door panels and will help protect you if your car is rammed from the side.) But always wear a seat belt no matter what kind of air bags you have.

For maximum protection, it's important to wear your seat belt and shoulder harness properly. The lap belt should be buckled across your lap and pelvis area -- never across your stomach. Buckling the seat belt across your stomach can cause internal injuries in an accident. The shoulder belt should be snug across your collarbone and chest. Don't wear it under your arm or behind your back. If you're at least 4'8" tall and weigh at least 80 pounds, a seat belt should fit you. Adults shorter than 4'8" and children should use a booster seat so that the shoulder harness and lap belt will fit, according to the NHTSA.

First of all, it's the law in every state, except for adults in New Hampshire. Twenty-six states and the District of Columbia have primary seat belt laws, which means a police officer can stop you simply for not wearing your seat belt. Twenty-three states have secondary seat belt laws, meaning an officer can cite you for not wearing your seat belt if you're stopped for another violation. (Some of these states allow police officers to pull over teen drivers simply for failure to wear a seat belt, however.) The Insurance Institute for Highway Safety says that when states strengthen their seat belt laws from secondary to primary, driver death rates decline by an estimated seven percent. In fact, the NHTSA estimates that seat belts saved 15,632 lives in the US in 2005.

If that's not enough to convince you, think about the other things you do to take care of yourself. Do you try to get regular exercise and keep high-fat foods to a minimum? If you have diabetes, do you try to keep your blood sugar under control? Do you avoid tobacco products because you don't want to risk cancer? Well, guess what? According to the NHTSA, motor vehicle crashes cause more deaths among people aged 15 to 24 than heart disease, diabetes, cancer, or any other cause. In 2003, on average, someone was killed in a motor vehicle accident every 11 minutes. So why not buckle up and increase your odds of survival? It only takes a second and it's a lot easier than passing up the french fries or giving up smoking.

-- Nancy Montgomery is an associate editor at Consumer Health Interactive.

References

First published March 23, 2005
Last updated February 28, 2008
Copyright © 2005 Consumer Health Interactive

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