Automakers began installing air bags in relatively large numbers in 1990, first in the steering wheel to protect the driver and later in the dashboard to protect the front-seat passenger. NHTSA now mandates that every new light truck have these dual air bags. Despite that fact that some children and adults have been injured or killed by deploying air bags, there’s still no doubt that air bags are an important safety feature. But it’s a question of policy that has led air bags to become objects of suspicion - or even fear - among many motorists. The most important safety feature in any car is a three-point seatbelt. When properly secured, seatbelts alone reduce the risk of fatal injury to drivers and front seat occupants by 45% and the risk of moderate-to-critical injury by 50%. Unlike air bags, seatbelts protect in all kinds of accidents, including frontal impacts, side impacts, rear impact and rollovers. Front-mounted air bags are effective only in frontal impacts - accidents that account for only about half of all highway fatalities. That’s why to be fully protected it’s vital to wear a seat belt even in cars with air bags.

Air bags are considered “supplemental” or additional restraints to the primary restraints, the seat belts. (The little “SRS” logo on the steering wheel in cars equipped with air bags stands for Supplemental Restraint System.) Some stupid schnooks refuse to wear their seat belts - about 40% of all American drivers and occupants, despite laws in 49 states that require adults to buckle up (New Hampshire, whose motto ironically is “Live Free or Die,” is the one exception). So, early on in the air bag game, NHTSA decided that air bags should protect unbelted folks in frontal collisions as well as those responsible citizens who always buckle up. Unfortunately, it takes a more powerful air bag to protect an unbelted person than a belted one, especially a large American male. To protect them, an air bag needs to burst out of the steering wheel or dashboard at nearly 200 mph, and that’s what NHTSA originally mandated. Over time, it was shown that those more-powerful air bags could harm or kill children or frail adults, and NHTSA later relaxed its rules to allow automakers to install “de-powered,” second-generation air bags that are 20% to 35% less powerful. These bags, which deploy with less force, are plenty powerful enough to protect people who wear their seat belts, but they should provide less chance of harm to children and to the elderly. If you are buying a used vehicle, not only should you try to confirm the air bags are in working condition, but you may wish to check to see which vehicles have de-powered air bags.

There was some evidence that passenger-side air bags that deploy vertically up the windshield are safer than air bags that release horizontally toward the passenger. Among the automakers with models that used vertical-deploying air bags were Ford, Honda and Nissan. Most new vehicles offer computer-controlled dual-deploy or dual-stage air bags. These smart air bags can deploy at two speeds, or not at all, depending on information sent to the computer from sensors located in the seat belts and front seats. In less severe accidents, air bags deploy at the lower, first stage, usually about 70 percent of full force. In more severe accidents, both stages are deployed. Seat sensors in newer systems also detect the weight of passengers and deploy the air bag only if the occupant is above a certain weight - helping to prevent air bag-related injuries to a child or small adult. In some vehicle systems, if no one is sitting in the passenger seat the air bag won’t deploy, thus saving repair costs. Systems offered in some luxury models help protect smaller drivers by deploying only the driver’s front air bag at the lower stage. Smaller drivers are detected by the forward position of the seat on the seat track. Newer vehicles also have an indicator that tells you if the front passenger air bag will deploy (that is, if it’s on or off) in the event of an accident. As of September 1, 2006, all vehicles are required to have advanced air bag systems. It’s advisable that you check with the manufacturer or dealer about the specific features that are part of the system on their vehicles.

With respect to side-impact air bags, NHTSA estimates that if they were standard in all vehicles on the road, in collisions involving side crashes some 700-1,000 lives per year could be saved. It also estimates that in side-impact crashes that involve at least one fatality, nearly 60% of the victims suffered significant brain injury. Side-impact protection advancements have occurred rapidly in recent years. Back in 2000, automakers were required to add extra padding around windows to help prevent head injuries. Now NHTSA has issued a final rule that will require manufacturers to assure that side-impact protection covers a wider range of occupant sizes and seating positions, through the installation of side (head) curtain and chest (torso) air bags in motor vehicles.

There are different types of side-impact air bag systems. On the NHTSA website you can review whether a vehicle's side air bags are curtain, tubular or a combination. The type affects the manner in which they deploy and the coverage and protection they provide. You can also see whether or not a vehicle qualifies as “meets specifications” - that is, whether it meets the voluntary guidelines for side air bag out-of-position tests. These guidelines are designed to minimize the potential of side air bag-related injury when a passenger (usually a child) sits too close to an air bag.