Even though air bags have killed dozens of small children, elderly people and short people, they are still a benefit overall, according to a study published Tuesday by researchers at Harvard University who have found that that benefit is as large as that of common medical procedures that cost the same.
But the study made clear that the balance of costs and benefits for passenger-side air bags is less favorable than for driver air bags.
A second study, by the Insurance Institute for Highway Safety, found that for 1992-1995, passengers in the right front seat were 18 percent less likely to die in head-on collisions if the car had air bags, although children under 10 had a 34 percent higher risk of dying in such cars. Both studies were published in the Journal of the American Medical Association .
The Harvard study showed that installing driver and passenger air bags in all cars, which costs about $400 each, was about as costly, in terms of lives saved, as many medical screenings, said John Graham, a professor of policy and decision sciences at the Harvard School of Public Health. The authors said their study was the first peer-reviewed scientific analysis of costs and benefits.
It was also a cold numerical look at a topic that has been the subject of emotional hearings in response to cases in which small children were killed by air bags that deployed in fender-benders, some at less than 10 mph.
The controversy has led the government to consider letting mechanics disconnect air bags.
Safety advocates, including Graham, point out that air bags are the first government-ordered equipment that increases risk for a large segment of the population, children. Researchers also say that statistically, air bags have little or no benefit for people over 65.
The study employed a counting system widely used in health care planning, in which researchers calculated the years of life that were saved or lost through air bags. For adults whose lives were saved, researchers said that on average, 40 years of life were added; for each child killed, 80 years of life were subtracted. Researchers also subtracted a small number of years from the adult total to account for adults who survived with permanent injuries, which reduced the quality of their lives.
The cost, per "quality-adjusted life year," was $24,000 for drivers and $61,000 for passengers, although researchers said the passenger figure could be reduced by $10,000 by getting children out of the front seat.