Excerpts from "Traffic Safety", a new book by Dr Leonard Evans, internationally recognized researcher and president of Science Serving Society

(From Chapter 12: Airbag benefits, Airbag Costs)  

Summary and conclusions

In July 2003 there were 257 million frontal airbags on the roads of the US. These cost their (in many cases unwilling) purchasers $54 billion. Assuming that the purchase cost is amortized linearly over an assumed 10-year vehicle life-span, this is equivalent to $5.4 billion per year. An additional $0.9 billion per year is spent replacing deployed airbags for a total annual cost of $6.3 billion.
Benefits of airbags were estimated by converting injury reductions to monetary equivalents using a National Highway Traffic Safety Administration report. This produced the following comparison of costs and benefits:

Costs exceed benefits by more than a factor of two for driver airbags, and by more than a factor of eight for passenger airbags.
Second generation airbags incorporating a series of changes and innovations are not expected to change these conclusions materially. They cause fewer injuries in low severity crashes, but likely provide lower average protection, leading to even lower benefits.

The benefit estimates ignore driver behavior changes stimulated by airbags that likely further reduce already low benefits. As belt wearing increases, the benefits of airbags decline. More effective safety policies leading to fewer crashes further reduce the benefits of airbags.
Airbags have many disadvantages in addition to cost. They have killed over 200 people in low severity crashes and caused other specific airbag injuries, including hearing loss. They introduce inconvenience, inequity in killing some classes of occupants (short females) to protect others (unbelted males), and violate medical ethical standards by forcing unacceptable risks on non-consenting, and often unwilling, subjects.

Even if airbags harmed no one, it is still indefensible public policy to compel consumers to purchase items that cost more than the benefits they provide. The present US airbag mandate that vehicles be fitted with airbags should be rescinded. Vehicle manufacturers should be permitted to offer airbags as options, giving consumers freedom of choice. Government's role should be to generate and disseminate reliable information to help consumers make informed choices.

Excerpts from the text:

 …The total number of driver and right-front passenger fatalities in cars and light trucks remained relatively unchanged from 1994 through 2002 even as the percent of drivers with airbags increased from 13% to 60% and the percent of passengers with airbags increased from 3% to 50%.2 This finding alone is sufficient to reject the claim that airbags would prevent 12,100 fatalities, as promised in the documentation used to justify the airbag mandate

...The goal is that when the occupant first contacts the airbag it should already be inflated. However, if the occupant is in the space into which the airbag inflates, he or she will be struck at up to 150 mph rather than striking the vehicle interior at a speed that could be as low as 10 mph. The impact from an inflating airbag poses a major risk of death or serious injury. People of any size are at risk if any part of their body is in the space into which an airbag deploys, as might happen if they were reaching to retrieve a dropped object. This risk was understood and named out of position since the 1970s. Drivers of short stature sitting at their most comfortable distance from the steering wheel are out of position.

 If credence is given to the large numbers of saved by the airbag anecdotal claims, then there must be a correspondingly large number of killed by the airbag cases to balance most of these, otherwise net effectiveness would be far higher than the values found in large-scale epidemiologic studies

Second generation airbags. 
In response to the many deaths and injuries caused by airbags, new design concepts keep being introduced. After 1998 so called second generation airbags appeared, so that some portion of the airbag fleet in 2003 consisted of such airbags. The effectiveness and cost estimates were all based on earlier first generation airbags.
Design changes include setting higher crash thresholds before deployment. This certainly reduces inflation-caused injuries in low severity crashes, and also reduces replacement costs. However, it also reduces the number of cases in which the airbag provides benefits, especially as airbags already do not deploy in over 15% of cases in which occupants are killed in frontal crashes.
Another change was reducing deployment forces - so called depowering. Lower power airbags reduce inflation injuries, but also provide less protection. In the limit one can depower an airbag so much that it hurts nobody, but also helps nobody. Depowering very likely reduces the net benefits.

Of the 77 drivers NHTSA identified as killed by airbags in low severity crashes, 75% were female. That is, for every male killed, three females were killed. For all drivers of cars and light trucks, FARS shows that for every male driver killed, 0.42 female drivers were killed. Thus females are over represented as fatalities caused by airbag inflation by a factor of 3.0/0.42 = 7.1. Of the female drivers killed, 48% were 62 inches or less (about 20% of females are 62 inches or less). Short females are more than 15 times as likely to be killed by airbags as average drivers. It was unmistakably determined that the airbag was the source of the death because the crashes were of such low severity as to not pose serious injury risk. If these deaths had been caused in an identical manner, but the crashes had been of higher severity, the deaths would have entered FARS in the usual way, and would have been incorrectly attributed to crash trauma. The conclusion is inescapable that many of the fatalities that in fact occur at the lower end of normal fatal crash severities are caused by airbags and not by crash trauma, and that the victims are preferentially short females. The net effectiveness reflects the difference between lives saved, preferentially large males, and lives taken, preferentially small females. Small females are being knowingly killed in order to save large males, a situation that society would hardly tolerate in any context other than airbags.

… William Haddon, a giant in the history of US injury control, discusses the nature of injuries in the broadest terms as the transfer of energy in such ways and amounts and such rapid rates as to harm people. He lists 10 strategies to reduce risks. The first is to prevent the marshalling of the form of energy in the first place. The airbag constitutes a topsy-turvy violation of this principle, by injecting yet more energy into an event in which energy is the source of harm. It is implausible to expect that 1.7 million annual airbag deployments, each an explosive event, will not cause human harm. The additional explosive energy released to inflate the airbag, in common with most sources of energy, produces its own set of injuries. For example, crashes generate much noise, but nothing approaching that produced by an airbag at the ears of an occupant.

Studies from Transport Canada estimate that during the eleven-year period 1990-2000, belts prevented 11,690 deaths and airbags 313. , Over this period benefits were estimated (in Canadian dollars) at $17.5 billion for belts and less than $0.5 billion for airbags.
Other issues
While over $60 billion has been paid for airbags (those on the roads plus those already retired), only minuscule resources have been assigned to better determine the benefits and costs associated with them. Even after 10 million deployments, no reliable estimates of how the device affects different levels of injuries have been published in peer-reviewed literature. No ongoing benefit-cost studies are being performed. The simple analysis presented here was supported entirely out of my own (note: Leonard Evans’) pocket. Spending one hundredth of one percent of the cost of airbags on research evaluating their in-use performance could provide more confident answers to many key questions.
The airbag is not worth anything near what it costs. As belt use increases it becomes worth still less. If wiser safety policy leads to fewer crashes, the airbag becomes worth even less.
Even if airbags did not have innumerable problems, including killing occupants in minor crashes, it is still indefensible public policy to compel consumers to purchase items that provide less benefit than they cost. The present US airbag mandate requiring that vehicles be fitted with airbags should be rescinded. Vehicle manufacturers should be permitted to offer them as options, giving consumers freedom of choice. Government's role should be to generate and disseminate reliable information to help consumers make informed choices.

Biography

Dr. Leonard Evans is an internationally recognized expert on Traffic Safety. After completing a 33 year research career with General Motors in 2000, he formed and is president of Science Serving Society under which he continues Traffic Safety research. He has more than 150 publications on traffic safety research and has been recognized with numerous major awards. These excerpts are from his latest book Traffic Safety Published August 2004. ISBN  0-9754871-0-8 445 pages (118 figures, 74 tables)     $99.50  You can order the book at: http://www.scienceservingsociety.com/ts/order.htm