Air bags: An update Authors: Judy N. Mikhail, RN, MSN, CCRN, CEN, and Donald F. Huelke, PhD, Flint and Ann Arbor, Michigan T here is overwhelming evidence that air bags save lives and reduce morbidity associated with motor vehicle crashes (MVC). >7 However, frontal air bags are also emerging as a source of injuries and death, s-I2 The number of air bag-related injuries is increasing as more automobiles are equipped with this supplemental restraint device. The public debate regarding the benefits and risks of air bags borders on hysteria. Knowledge of air bag-related patterns of in- jury and death equips the emergency nurse to antici- pate specific injuries, identify occult injury, and serve as a credible source for injury prevention information. Yet, research on this topic is published primarily in nonnursing journals. This article will provide an overview of the history, design, and effectiveness of frontal air bags, a review of air bag-related injuries and deaths, and the development of "smart" air bag technology and side-impact air bags. Currently there are few cars available with side air bags, thus there are few to no data published on their actual perfor- mance in MVCs. Therefore for the purposes of this ar- ticle, the term air bag refers only to frontal air bags located either in the steering wheel or dashboard. History Air bag patents were first issued in the 1950s. Automakers showed little interest in further air bag development during the next 25 years. A federal man- date requiring that air bags be placed in cars as stan- dard equipment did not become a law until 1987. A second federal mandate in 1991 required that air bags be installed in all new cars by the beginning of model year 1998 and in all new light trucks by the beginning of model year 1999. Air bags are now standard equip- ment on most passenger cars and light trucks. As of the end of model year 1996, approximately 56 million vehicles for sale in the United States had driver-side air bags; today nearly 27 million vehicles have addi- tional frontal passenger air bags. v Judy Mikhafl is Trauma Coordinator, Hurley Medical Center, Flint, Michigan. Donald E Huelke is Research Scientist, University of Michigan Transportation Research Institute, Ann Arbor. For reprints, write Judy Mikhail, RN, MSN, CCRN, CEN, Trauma Services, Hurley Medical Center, One Hurley Plaza, Flint, M148503- 5993. J Emerg Nurs 1997;23:439-445. Copyright © 1997 by the Emergency Nurses Association. 0099-1767/97 $5.00 + O 18/1/84938 Design An air bag is a rubber-lined nylon fabric bag folded into the steering wheel or dashboard. A frontal or near-frontal impact at approximately 12 mph or greater triggers the air bag sensors, which are located in varying positions depending on the structure of the vehicle. The air bag inflates with a harmless gas (pri- marily nitrogen) within 50 milliseconds of impact to create a protective cushion between the occupant and the vehicle interior. The velocity of air bag infla- tion is between 150 mph and 200 mph. Within 2 sec- onds after impact the gas in the air bag reaches atmospheric pressure and begins to deflate. Cornstarch or talcum powder lubricates the bag as it deploys and may form a harmless white powder or dust around the deployed air bag. Once the air bag has been deployed, it must be replaced. Insurance companies generally include this as part of the cost of repairing crash damage. An air bag is a rubber-lined nylon fabric bag folded into the steering wheel or dashboard. A frontal or near-frontal impact at approximately 12 mph or greater triggers the air bag sensors, which are located in varying positions depending on the structure of the vehicle. Effectiveness Air bags are designed to provide supplemental pro- tection for belted front seat occupants in a frontal crash. They are not designed to inflate in most side, rear, or rollover crashes. However, if forward deceler- ation of the vehicle is great enough during the crash, regardless of the initial direction of impact, then the sensors will deploy the air bag. Lap-shoulder belts re- main the most effective restraint for protecting occu- pants in severe crashes. 7 Air bags that are used October 1997 439