Air Bags Earn Good Safety Record

Question: I would like to know how many accidental deployments of air bags have occurred and how many injuries have resulted. Perhaps I am in the minority, but I don’t like air bags. The idea of driving around with an explosive device 14 inches from my face is most unnerving. D. H.

Answer: Automobile safety experts say that fewer than 10 cases of inadvertent deployments of air bags have occurred since they were developed and that perhaps no such events have occurred in recent years.

Auto makers have designed sensors, electronic systems and firing mechanisms for air bags with reliability standards derived from the space program, aiming to achieve a 99.999% rate of reliability.

The success is remarkable in many ways, especially considering that the air-bag sensor must determine whether a crash is occurring in 8- to 9-thousandths of a second and order the air bag firing mechanism to inflate the bag. Despite your misgivings, air bags have met with a good deal of consumer acceptance. The evidence is pretty strong that air bags make an important contribution to auto safety, though at a high price.

The Insurance Institute for Highway Safety has recently released two studies of air-bag effectiveness. The safety institute looked at cars of the same model to see how ones equipped with air bags compared in death statistics to those not equipped. The data shows a 28% reduction in deaths in front-collision accidents in cars with air bags and a 19% overall reduction in all types of accidents. The safety institute research appears to show that air bags make an important contribution to safety even when a driver is strapped in with a seat and shoulder belt. The institute found a 10% lower death rate in accidents where a driver was protected by both air bag and harness, compared to just a harness.

Brian O’Neill, safety institute president, thinks the roughly $500 cost of an air bag is a good deal. A 24-m.p.h. crash typically causes a broken nose or broken jaw, even when a driver is strapped in. At 30 m.p.h., there is a significant probability of brain injury, because a person’s head will still hit the steering wheel even when the driver is wearing a belt.

Having said all this, you might wonder whether air bags ever cause problems. In a small number of cases, they have. Air bags are inflated by sodium azide, a substance classified as a rocket engine propellant. The gas gets hotter than steam and must be carefully contained.

The Center for Auto Safety, a consumer organization that also advocates air bags, reports that at least one woman received significant facial burns when hot gases from an air bag leaked onto her face. In several other cases, individuals have received burns to their hands from gas vents that were poorly designed.

Clarence Ditlow, director of the safety center, said air bags are far more reliable than seat belts, which fail about 2% of the time in accidents. Ditlow said that the only significant number of inadvertent air bag deployments occurred in some 1989 Chryslers, which had sensors programmed to trigger in crashes of 8 m.p.h. or more. The industry standard is 12 m.p.h.

Since that problem was identified, the modules have been redesigned and many of the original bags replaced. Moreover, federal studies seem to show that an inadvertent deployment is unlikely to cause an accident.