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Airbags Information
This factsheet is a short literature review of airbags and includes advice about common concerns with airbags, and how to use them safely. It is comprised of the following sections:
Car occupants form 64% of all road casualties. In 2006, 171,000 people were killed or injured while travelling in cars. Of these, 150,707 (88%) were drivers or front seat passengers. Table 1 Car Occupant Casualties 2006
Table 1, which shows the number of car occupant casualties during 2006, sorted by severity of injury, and seating position. Source, ‘Road Casualties Great Britain: 2006’, Published by The Stationery Office. Seat belts have proved to be very effective in reducing such casualties. However, in frontal collisions, car occupants are still injured by being thrown onto unpadded parts of the car interior such as the steering wheel and the dashboard. Therefore, in recent years, airbags have been introduced to provide further protection. However it must always be remembered that air bags are an addition rather than an alternative to seat belts. The study by Simon Barry et al makes it clear that seat belts are not only cheaper and less prone to negative effects than airbags. They are also more effective in frontal collisions and in a wide range of other crashes where an airbag is ineffective. Airbags inflate rapidly (and then immediately deflate), cushioning the occupants and preventing or reducing the level of contact with the steering wheel or dashboard. They need to inflate at an extremely fast rate in order to be fully inflated by the time a person’s body begins to move in reaction to a collision. The bigger the airbag, the faster it has to inflate. In general, European airbags hold 35 litres of gas propellant and fully inflate within 25 milliseconds, which means that they have to expand at anything up to 160 mph. American air bags, usually holding 60 litres of gas, have to inflate even faster. The area of space within the car taken up by the airbag as it inflates is known as the ‘airbag deployment zone’. Sensors within the vehicle monitor the direction and severity of an impact and fire the airbag if the severity and direction warrants it. The impact should be greater than 20mph, and in a frontal direction. Rear end shunts should not fire the airbag. As the airbag module fires, it and the gas it generates are hot, so car occupants may suffer minor burns. When airbags were first introduced in the United Kingdom and Europe, the only research on their effectiveness came from the United States of America. These studies looked at the bigger airbags used in America which were designed to protect a driver not wearing a seat belt. (American seatbelt wearing rates were lower than British ones, but are now catching up.) These airbags inflate very fast and have caused some fatalities. The National Highway Traffic Administration in the United States estimates that of 4,000 car occupants saved by airbags another 60 would still have been alive if the devices had not been fitted to the vehicles they were travelling in. Airbags are now much more common in European vehicles and research on their effectiveness is now available. However a lot of this research is aimed at the development of smart airbags and is looking at cases where injury has taken place.
In a review of “Driver Airbag Deployments in Europe and Japan to date”, Andrew P Morris et al found that there was some evidence to suggest that unrestrained drivers in frontal impacts are more likely to sustain greater severity of injuries from an air bag. However this must be seen in relation to the severity of injuries that would be sustained by an unbelted driver in a vehicle without an airbag. It reinforces the need to use airbags with seatbelts. Rearward Facing Child Seats Forward Facing Child Seats To prevent this, fit them securely, outside the deployment zone of the airbag. Either fit them in the back of the car if this means that they are clear of any side impact bags, or if it must be fitted in the front, ensure that the car seat is as far back as possible, and stays there, and that this takes the child and seat out of the deployment zone. The car manufacturer will be able provide information on the extent of the deployment zone. Pregnant Women Driver Positioning Nothing should impede the deployment of the air bag. If the occupant’s arm gets in the way then injury can occur. Drivers should ensure that they use the “ten to two” or the “quarter to three” position of their hands on the wheel because if they have their arm across the wheel when the airbag fires, the force of the airbag is likely to break the limb. Hearing Loss Shorter Lighter Drivers Drivers with Disabilities A number of motor manufacturers are developing ‘smart’ airbag systems, which, can detect seat and driver position and alter the performance of the airbag accordingly. Some have already begun to install ‘restricted’ smart airbags, which only inflate if sensors indicate that a person is sitting in the seat. These developments will hopefully resolve some of the current problems associated with airbags. Airbags are an effective secondary safety measure that reduces the risk of injury for vehicle occupants, in more severe collisions. RoSPA supports the fitment of airbags in vehicles if they are used in conjunction with - but not in place of - seat belts. However, a number of problems with airbags have been identified, although many of these relate to American airbags. UK car users can avoid such problems by the following steps:
Parenteau,CS, Shah M, Desai T, and Frampton R, US and UK Belted Driver Injuries with and without Airbag Deployments – A Field Data Analysis 1999 Society of Automotive Engineers, Inc. Lau I V, Horsch J D, Viano D C, Andrzejak D V. Mechanism of Injury from Air Bag Deployment Loads. Accident Analysis and prevention Vol25 No1 pp29-45 1993 Morris A P, Thomas P Brett M. Foret-Bruno J-Y, Thomas C, Otte D and Ono K. “A Review of Driver Airbag deployments in Europe and Japan to Date”, National Highway Traffic Safety Administration, 15th International Conference on the Enhanced Safety Vehicles Congress, Melbourne Australia, May 1996, 122-131. ISBN DOT HS 808 465 Buckley G, Setchfeild N and Frampton R Two case reports of possible noise trauma after inflation of air bags in low speed crashes. British Medical Journal 1999, no 318 pp499-500 Barry S, Ginpil S, O’Neill TJ, The Effectiveness of Air Bags Accident Analysis an Prevention 31 (1999) pp781-787 Huelke DF, Moore JL, Compton TW, Rouhana SW, Kileny PR Hearing Loss and automobile airbag deployment Accident Analysis and Prevention 31 (1999) PP789-792
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