Correspondence

Airbag Safety and the Distance of the Driver from the Steering Wheel

N Engl J Med 1998; 339:132-133July 9, 1998

Article

To the Editor:

Actuarial data indicate that driver-side airbags reduce the overall risk of death from a car accident by 11 percent,1 but airbag-induced injuries (both fatal and nonfatal) have been reported.2 The driver's proximity to the airbag is an important safety issue. Under a new government policy, drivers are being encouraged to maintain a safe distance from the steering wheel or, if that is not feasible, to obtain a manual cutoff switch for their airbags.3 Yet drivers may not properly estimate their proximity to the steering wheel.

In order to evaluate the degree of misperception, we conducted a cross-sectional survey of 1000 drivers at gas stations in the Boston metropolitan area. Proximity was defined as the distance between the center of the steering wheel and the bridge of the driver's nose, as perceived by each driver and as measured with a tape measure by trained interviewers. We compared the perceived and actual distances, documenting the number of drivers who estimated that they were or who actually were sitting with the bridges of their noses within 12 in. (30 cm) of the steering wheel.

The correlation between perceived and actual distances was very low (r=0.24), with some drivers underestimating and others overestimating their proximity (Figure 1Figure 1Perceived and Actual Distances from the Driver's Nose to the Steering Wheel.). Although 234 of the drivers (mostly women) thought that they sat within 12 in. of the steering wheel, only 22 drivers (19 women and 3 men) actually did. Of these 22 drivers, only 8 correctly perceived that they sat within 12 in.

A limitation of our study is that the new regulation defines the safe distance as 10 in. (25 cm) from the breastbone to the steering wheel. We suspect that a considerable number of drivers will also misperceive their risk according to this alternative definition of safe distance.

Drivers who think they sit too close to the wheel but actually do not may be inappropriately concerned about their safety and disconnect their airbag systems, thus losing safety benefits. In contrast, drivers who actually sit too close but do not think they do may not be concerned enough. Since a petition for airbag disconnection must be submitted by the owner of the vehicle and the driver's risk status cannot be corroborated, physicians and policy makers should be aware of this problem of misperception and take a proactive approach to help identify the people truly at risk for injury from airbags. Drivers should be encouraged to measure objectively their distance from the airbag in a normal driving situation.

Maria Segui-Gomez, M.D., M.P.H.
Jonathan Levy, B.A.
John D. Graham, Ph.D.
Harvard Center for Risk Analysis, Boston, MA 02115-5102

3 References

1. 1

   Kahane C. Fatality reduction by air bags: analyses of accident data through early 1996. Washington, D.C.: National Highway Traffic Safety Administration, 1996.
   

2. 2

   Cases from the Special Crashes Investigation Program. Washington, D.C.: National Highway Traffic Safety Administration, 1997. (Or see: http://www.nhtsa.dot.gov/people/ncsa/datadult.html.)
   

3. 3

   Approval of installation of air bag on-off switches for certain motor vehicle ownersMMWR Morb Mortal Wkly Rep 1997;46:1098-1099
   

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   William F. Donaldson, Stephen E. Hanks, Ahmad Nassr, Molly T. Vogt, Joon Y. Lee. (2008) Cervical Spine Injuries Associated With the Incorrect Use of Airbags in Motor Vehicle Collisions. Spine 33:6, 631-634
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   Guy Wallis, Astros Chatziastros, Heinrich Bülthoff. (2002) An Unexpected Role for Visual Feedback in Vehicle Steering Control. Current Biology 12:4, 295-299
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   Jayachandran N. Variyam, Young Shim, James Blaylock. (2001) Consumer Misperceptions of Diet Quality. Journal of Nutrition Education 33:6, 314-321
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   P. Scuffham, D. Battistutta. (2000) Misperceptions of "objective measurements"?. American Journal of Public Health 90:6, 988b-989b
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   Om P. Sharma, Xavier R. Mousset. (2000) Review of Tricuspid Valve Injury after Airbag Deployment: Presentation of a Case and Discussion of Mechanism of Injury. The Journal of Trauma: Injury, Infection, and Critical Care 48:1, 152
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   M Segui-Gomez, J Levy, H Roman, K M Thompson, K McCabe, J D Graham. (1999) Driver distance from the steering wheel: perception and objective measurement.. American Journal of Public Health 89:7, 1109-1111
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