Air bag advances curb highway toll

Since Ralph Nader's seminal book "Unsafe at Any Speed" came out 40 years ago, seat belts, padded dashboards, collapsible steering columns, improved bumpers, and other safety features have become standard fare on cars and trucks. After seat belts, the most significant advance in automobile safety has been the air bag.

Air bags are gas-inflated cushions that rapidly discharge from compartments hidden in steering columns, dashboards, roof rails, doors, and seats, hyper-inflating to protect a vehicle's safety-belted adult drivers and passengers.

Driver and front-passenger air bags have been required in cars by the federal government since the 1998 model year (since 1999 for light trucks). Mercedes-Benz first put air bags in all its models in 1986.

Frontal air bags saved 13,967 lives from 1987 to 2003, according to the National Highway Traffic Safety Administration. The NHTSA calculates that using a seat belt and having an air bag lowers the incidence of head injury during a crash by 85 percent.

In recent years, an armada of air bags has been added to cars and trucks. Some rides, such as the BMW M3, now possess as many as eight of the nylon inflatables.

Side-impact air bags, which Volvo debuted in the mid-1990s, are one of these bonus bladders. Variations shield the pelvis, chest, and head and can deploy from the door, seat, or roof of a vehicle. Side curtain air bags protect the head and, in some models, remain inflated for up to five seconds during rollovers. BMW was an early curtain pioneer.

Side air bags not only help passengers in more rollover-prone sport utility vehicles, but they also protect occupants of smaller cars from these same light trucks.

The Insurance Institute for Highway Safety is a nonprofit trade group that crash-tests vehicles and conducts related research. The organization's chief operating officer, Adrian Lund, said of SUVs, "When these things hit you on the side if you're in a car, basically their hood is right at your head."

Side air bags can provide a cushion between bodies and intruding SUVs.

"We've seen about a 45 percent reduction in fatal injuries for vehicles that are equipped with side air bags," Lund said.

The NHTSA is working on upgrading side-impact safety standards for all passenger vehicles.

"We're estimating that the new side-impact standards are probably going to save between 900 and 1,200 lives per year," said NHTSA spokesman Rae Tyson.

Other air bag innovations continue apace. General Motors, for example, decided in February 2005 that the 2006 Buick Lucerne and 2006 Cadillac DTS would include a dual-depth passenger-side bag. These bags inflate to different girths, depending on variables such as seat position, the severity of the crash, and whether the seat belt is clasped.

Dual-stage air bags, present on several new Volvo models, work slightly differently. With this technology, a sensor measures the severity of a crash and seat-belt usage to adapt air bag inflation speeds; a severe crash results in a full, rapid deployment, while a fender-bender triggers a slower 70 percent inflation.

Advanced frontal air bags -- the generic term for GM's dual-depth technology -- are configured to render moot the public outcry over first-generation air bags, which claimed that the bags crushed children and small adults. Automakers and safety advocates countered by pointing out that children 12 years old and younger should never sit in the front seat. NHTSA statistics show 90 percent of the 230 people killed by air bags since 1990 were infants.