"We found lower fatality risks across the board - among older and younger drivers, male and female drivers, and drivers of both small cars and larger passenger vehicles," says Anne McCartt, Institute vice president for research and an author of the study.
Head-protecting side air bags reduce driver fatality risk when cars are struck by SUVs and pickups, not just other cars. This is important because risks go up for occupants of cars struck in the side by the higher riding vehicles. In particular, the car occupants' heads are vulnerable to being struck. The Institute's study confirms that side air bags are reducing fatality risk in these crashes. Automakers are cooperating to reduce vehicle incompatibilities in both side and front collisions that lead to car occupant injuries, and a big part of this is to equip vehicles with side air bags.
The overall research findings echo those of a 2003 Institute study of side air bag effectiveness in cars. Data weren't sufficient then to compute fatality risk reductions for drivers of SUVs, but this time around there were enough data. Fatality risk in SUVs went down 52 percent with head-protecting side air bags and 30 percent with air bags that protect the chest and abdomen but not the head.
The study includes three sets of effectiveness estimates. One is based on the same car models as the Institute's 2003 study. Researchers also analyzed the effectiveness of side air bags in newer cars (2001-04s during 2000-04) and in a combination of newer and older cars (1997-2004 models). Estimates of side air bag effectiveness in SUVs are based on newer models only (2001-04s during 2000-04).
Data are from the federal Fatality Analysis Reporting System and General Estimates System. The authors calculated fatality risk in cars without side air bags, with head-protecting side air bags, and with air bags that protect the chest and abdomen but not the head (almost all vehicles with head-protecting air bags provide torso protection too). Compared with the 2003 study, researchers used a refined method of accounting for driver differences and for vehicle differences besides the presence or absence of side air bags.
Both the 2003 study and the new one reveal side air bag benefits, but the estimates of effectiveness differ. The best estimates from the new analyses, based on the combined set of vehicles (1997-2004 models), show somewhat smaller benefits of head-protecting side air bags and larger benefits of torso air bags, compared with the earlier study. The difference in effectiveness for these two air bag types was smaller when researchers looked at newer cars only (2001-04s during 2000-04).
"These variations in the findings depending on the datasets of vehicles aren't surprising. Side air bags are relatively new, and the datasets still are small. This means fluctuations in the results are to be expected," McCartt says. "What's important is the consistency of the overall pattern. Regardless of what vehicle model years we included, the benefits of side air bags were revealed - and the benefits were greater for head-protecting side air bags than for ones that protect the chest and abdomen but not the head."
Findings track results of the Institute's side crash tests conducted since 2003 for consumer information. All 33 current models with good ratings in this test are equipped with head-protecting side air bags, while very few poor performers are.
Although federal regulations don't require side air bags in passenger vehicles, more and more manufacturers are installing them. In part this is the result of a voluntary agreement among automakers, forged in 2003, to improve occupant protection in side impacts with SUVs and pickups - an agreement that essentially will result in all cars, SUVs, and pickups being equipped with side air bags with head protection by the 2010 model year.
About four of every five new car and SUV models already have standard or optional side air bags that include head protection. This is a huge increase since side air bags were introduced in a handful of models in the mid-1990s.
"Once every passenger vehicle on the road has side air bags that include head protection for front-seat occupants, we can save as many as 2,000 lives per year," McCartt concludes.