Q&As: Airbags

March 2009

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1 What are airbags?

Airbags are cushions built into a vehicle that protect occupants from hitting the vehicle interior or objects outside the vehicle (for example, other vehicles or trees) during a collision. The instant a crash begins, sensors start to measure impact severity. If the crash is severe enough (at or above the airbag deployment threshold), the sensors signal inflators to fill the bags with gas. The bags fill in a fraction of a second to cushion occupants. Occupant protection is maximized when safety belts are used in conjunction with airbags.

Video: frontal driver airbag deploying from the steering wheel

Frontal airbags: Most vehicles have airbags that deploy in frontal crashes to protect front-seat occupants. The frontal airbag for the driver is stowed in the steering wheel. The frontal airbag for the front passenger is stored in the instrument panel.

Some manufacturers provide knee airbags, mounted in the lower instrument panel. Knee airbags distribute impact forces to reduce leg injuries. They also help reduce forces on an occupant's chest and abdomen by controlling occupant movement.

Side airbags: Increasing numbers of vehicles also have airbags that deploy in side impact crashes. Side airbags are usually smaller than frontal airbags and deploy from the vehicle seatback, door, or roof to protect front- and sometimes rear-seat occupants.

Some side airbag systems protect only the torso (chest, abdomen, and pelvis), some protect only the head, and some protect both the head and torso. Airbag systems that protect both the head and torso provide optimal protection.

Head-protecting airbags may extend into the rear seating area. Rear seats may also have head-protecting side airbags separate from those in the front seat or airbags that provide torso protection.

Frontal dual airbag system	Side airbags to protect the head or head and torso
Side airbags to protect the head and torso

Video: full frontal test with and without airbag/safety belt, 95th percentile male dummy

2 Why do we need airbags?

Frontal airbags: In serious frontal crashes, the occupants inside the vehicle do not stop immediately, but continue moving forward. Frontal airbags are designed to work with lap/shoulder belts to protect the heads and chests of occupants from hitting the steering wheel, instrument panel, or windshield. If occupants strike these surfaces hard, they can sustain serious or fatal injuries.

Side airbags: Side airbags are important in side impacts where a properly belted occupant can still be struck by an intruding vehicle or object coming from the side. Side airbags that offer head protection are particularly important because they may be the only thing between an occupant's head and the front of a vehicle, a tree or other object, or the ground in the event of a rollover.

3 Are airbags required in all vehicles?

Frontal airbags: Since the 1999 model year, the federal government has required automakers to install driver and passenger airbags for frontal impact protection in all cars, light trucks, and vans. Most new vehicles had dual frontal airbags even before they were required safety equipment. Airbags grew in popularity starting in the early 1990s, and by the 1995 model year, virtually all cars and many light trucks had driver airbags. By the 1997 model year, most also had passenger airbags

Side airbags: Side airbags are not required by the government, but they are offered as either standard or optional features by many vehicle manufacturers. Eighty-eight percent of all 2009 passenger vehicle models offer side airbags (75 percent as standard equipment, 13 percent as optional equipment). Of 2009 model year vehicles, side airbags were provided as standard or optional equipment in 95 percent of cars, 100 percent of SUVs, and 66 percent of pickups. In September 2007, the National Highway Traffic Safety Administration (NHTSA) issued new side-impact safety requirements that likely will result in more manufacturers voluntarily equipping their vehicles with side airbags. The new standard requires automakers to provide increased head and torso protection for front seat and rear seat occupants in side-impact crashes but doesn't mandate side airbags specifically.

Models with side airbag head protection systems

4 When do airbags deploy?

Airbags are designed to deploy only when they might be needed to prevent serious injury. In order for airbags to be effective they must deploy early in a crash; in a frontal crash this typically occurs within the first 50 milliseconds (0.05 seconds). A vehicle's airbag control module relies on feedback from crash sensors to predict whether an event is severe enough to warrant an airbag deployment.

Frontal airbags: Frontal airbags are designed to inflate in moderate to severe frontal crashes. Among airbags with advanced features that include a safety belt sensor, there are different inflation thresholds depending on whether people are using their safety belts. One threshold used by airbag designers is "must deploy" which includes a situation such as an impact into a rigid wall of 10-12 mph for unbelted occupants. The "must deploy" threshold is slightly higher — about 16 mph — for belted occupants because the belts alone are likely to provide adequate protection up to these moderate speeds. Frontal airbags may deploy to help protect occupants in side impacts if there is sufficient forward deceleration during the crash. For example, if a vehicle is moving forward at the time of a side impact, frontal airbags can help prevent serious injuries.

Advanced airbags compliant with government crash performance standards have been required in all passenger vehicles effective with model year 2007. Advanced airbags are designed to suppress deployment if weight sensors in the seat detect that a front-seat passenger is small or in a child safety seat. Advanced airbags also can deploy at a lower energy level or pressure when passengers are small or out of position, or if the crash is of very low severity.

Side airbags: Because of the small space between an occupant and the side of the vehicle, side airbags must deploy very quickly to cushion occupants from intruding vehicles or objects. Some airbags typically deploy within the first 10-20 milliseconds of a side crash. "Must deploy" thresholds can be as low as 8 mph for narrow object crashes (e.g., trees and poles) and 18 mph for the more distributed side crashes (vehicle-to-vehicle crashes). Several auto manufacturers deploy the side airbags in frontal crashes to help control occupant movement during the rebound phase of a crash. Some curtain side airbags may stay inflated longer to protect occupants in rollover crashes. Allowing the airbags to remain inflated or triggering their deployment during a rollover can help prevent full or partial ejection of occupants.

5 Is there a problem with non-deploying front airbags?

An article in The Kansas City Star in 2007 raised the possibility that non-deploying front airbags may be a major problem in fatal crashes.1 The article relied upon data from the Fatality Analysis Reporting System (FARS), a census of fatal crashes in the United States that primarily relies upon police reports.

An Institute study reviewed airbag deployment status for fatal frontal crashes contained in FARS and in the National Automotive Sampling System/Crashworthiness Data System, a sample of tow away crashes with detailed data from crash investigators. Failures of front airbags to deploy in fatal crashes where the front airbags usually would be expected to deploy were less frequent than suggested by FARS data, which had a substantial number of coding errors.2 Institute researchers estimated that 1-2 percent of front occupant deaths represented potential system failures where deployment would have been expected. Some of these deaths could not have been prevented by deployed airbags.

6 Are airbags effective? Do they save lives and reduce injuries?

Frontal airbags: NHTSA estimates that as of Jan. 1, 2009, more than 28,000 people are alive because of frontal airbags. Eighty-two percent were drivers and 18 percent were front seat passengers. Forty percent were belted and 60 percent were unbelted.3

In frontal crashes, frontal airbags reduce driver fatalities by 29 percent and fatalities of right front passengers aged 13 and older by 32 percent. The fatality reduction in frontal crashes is larger for unbelted drivers (34 percent), compared to belted drivers (21 percent). NHTSA estimates that the combination of an airbag plus a lap and shoulder belt reduces the risk of death by 61 percent, compared with a 50 percent reduction for belts alone in frontal crashes.4

Side airbags: Institute analyses of the efficacy of side airbags with head protection showed a 37 percent reduction in a car driver's risk of death in driver-side crashes. The fatality risk was reduced by 26 percent when the side airbag was designed to protect only the torso. The fatality risk for SUV drivers was reduced by 52 percent with head-protecting side airbags and by 30 percent with torso-only airbags.5

7 Can airbags injure people?

Frontal airbags: Yes. Occasionally, the energy required to quickly inflate frontal airbags can cause injury. Fortunately, most of these injuries are minor scrapes and abrasions. Serious injuries and deaths are relatively rare.

In 1997, the federal government allowed manufacturers the option to reduce the energy or force of frontal airbags. Indications are that redesigned airbags and efforts to educate motorists are reducing airbag-related injuries and deaths. The number of airbag deaths appears to be shrinking even as the number of airbag-equipped vehicles increases. One study found that children exposed to airbag deployments in 1998 and newer model passenger cars were half as likely to sustain significant injury compared with children in pre-1998 passenger cars and minivans.6 A 2006 study by NHTSA reported that redesigned airbags reduced fatality risk to child passengers by 45 percent as compared with pre-1998 airbags — without changing the beneficial effects for adults.7 A 2008 study showed an 11 percent decrease in risk of fatality for drivers and passengers with the redesigned airbags, as compared to pre-1998 airbags.8 In 2008, a panel of highway safety researchers, insurers, and automakers completed a six-year evaluation of the real-world performance of advanced technology airbags. The panel concluded that redesigned frontal airbags improved protection for the youngest vehicle occupants without increasing risk of injury or death for adults as compared with previous airbag generations.9

The Blue Ribbon Panel for the Evaluation of Advanced Technology Airbag website

Side airbags: Like frontal airbags, side airbags have the potential to cause injury. However, side airbags typically are smaller and deploy with less energy than frontal airbags.

8 Who has been injured or killed by airbags?

Frontal airbags: NHTSA estimates that since 1990, more than 290 deaths have been attributable to frontal airbag inflation in low-speed crashes. Nearly 90 percent of deaths occurred in vehicles manufactured before 1998 and approximately 68 percent were passengers. More than 90 percent of the passenger fatalities were children and infants, most of whom were unbelted or in rear-facing child safety seats that placed their heads close to the deploying airbag.3 More than 80 percent of people killed were unbelted or improperly restrained. Unbelted occupants are likely to move forward if there is hard braking or other violent maneuvers before a frontal crash. These occupants can end up on top of, or extremely close to, the airbags as they begin to inflate. Short and elderly drivers can be vulnerable to inflation injuries from frontal airbags because they tend to sit close to the steering wheel.

Frontal airbags have changed considerably since the early 1990s, when the majority of airbag-related deaths occurred. The chief difference is a reduction in the energy (or power levels) with which airbags deploy. In addition, because of public education that children are safer in rear seats, and state laws requiring children to sit in the rear, children increasingly are sitting in rear-seat positions. These and other changes have contributed to the drastic decline in frontal airbag-related deaths.

Side airbags: According to NHTSA's Special Crash Investigations, 3 vehicle occupants have been seriously injured due to side airbag inflation. One was an elderly male driver who suffered multiple rib fractures, and 2 were middle-aged female drivers who suffered injuries to the spleen and ribs. NHTSA has reported only one child who has been injured by a side airbag; a 3-year old sitting unrestrained in the front seat sustained minor facial skin lacerations from the side airbag cover. No children are known to have been seriously or fatally injured by a side airbag. A recent study of children in side crashes found no increased risk of injury to children age 15 and younger associated with side airbag deployment. This study did not separate out head and torso airbags.10

9 What can be done to prevent injuries from frontal airbags?

Drivers: It is recommended that drivers sit with their chests at least 10 inches away from the center of the steering wheel. Many newer airbags take into account seating position and deploy with less force if an occupant is sitting close. However, for drivers of older vehicles who cannot get far enough away from the steering wheel, pedal extenders or an airbag on/off switch may be an option.

Only if it is not possible to get at least 10 inches from the steering wheel should an on/off switch be considered. Even if a safety belt is used, sitting this close to an airbag puts a driver's face at risk.

Infants and children: How and where infants and children are restrained in a vehicle can reduce the likelihood of sustaining an airbag-related injury. Infants, particularly those in rear-facing safety seats, should never sit in the front because this puts an infant's head too close to the frontal airbag. Rear seats are always safest for infants and children. Twelve states require children to sit in the rear whether or not the vehicle has an airbag, and two states require them to be in the rear when there is an active frontal passenger airbag. Even if your state's law does not require children to sit in the rear, children younger than 12 should always sit restrained in rear seats.

Seat belt and seating requirements by state

If an adult is transporting too many children for them all to sit safely and comfortably in the back seat(s), the oldest child may ride up front. In this situation, the seat should be as far back as possible and the child should be securely buckled in a lap/shoulder belt and sitting back in the seat. If a driver routinely transports too many children to put them all in the back seat, an airbag on/off switch may be considered.

Nearly all older children killed by frontal airbags were either unbelted or improperly belted. But even a belted child can be at risk by wiggling out of position or sitting on the edge of the seat, putting the head too close to the airbag. Proper belting and positioning are essential to safety.

10 What can prevent injuries from side airbags?

The risk of injury from a side airbag in the front and rear seats is extremely low for properly restrained and positioned adults or children. Children should not lean against the door area where the airbag is stored because the initial deployment force may be harmful. It is important for parents to understand that, with or without an airbag, children leaning against a door or lying down on a seat with their heads near the door or sides of a vehicle are at higher risk of injury in the event of a side impact.

The Side Airbag Out-of-Position Injury Technical Working Group (TWG) was formed because of concerns about potential injuries, particularly to small children who might lie down or assume other positions against a deploying side airbag. The TWG has a test protocol to assure that the inflation injury risk from deploying side airbags remains low. All vehicle manufacturers have committed to follow this protocol when designing new side airbag systems. According to NHTSA's online resource, safercar.gov, 91 percent of vehicles with side airbags conform to these voluntary guidelines.

NHTSA brochure: Buying a Safer Car

Rear-facing child restraints SHOULD NOT be used in the front seat with a passenger airbag. The forces of the inflating airbag against the back of the restraint can cause serious, even fatal, head injuries. Video: clip of this test

 

Pregnant women: Women in the late stages of pregnancy may not be able to get their abdomens far away enough from the steering wheel to be safe. There can be a risk of fetal injury from a frontal airbag if it inflates. However, without the airbag, there is a risk of fetal injury from hitting the steering wheel. Women in the late stages of pregnancy should avoid driving whenever possible. If they must drive, the combination of properly positioned safety belts and airbags offers the best protection.

11 Who needs an airbag on/off switch for frontal airbags?

The federal government has procedures allowing the very few people who may be at risk of serious airbag injury to get switches, but these aren't appropriate for most people. Installation of switches is permitted until September 1, 2012. Most motorists can position themselves properly to avoid being too close to an inflating airbag. Airbags are designed to be used in conjunction with safety belts; using a belt will reduce the chances of an occupant sliding too close to a deploying airbag.

Drivers: If a driver is unable to sit at least 10 inches away from the steering wheel, the installation of an airbag on/off switch could be considered. However, most 1998 and newer vehicles have redesigned airbags with less powerful inflators that reduce serious injury risk and without an airbag, a driver's face is likely to hit the steering wheel in a frontal crash. Once the risks of deactivating an airbag are understood, the benefits should be weighed carefully against these risks.

Passengers: Properly restrained adult passengers sitting back in the seat are not at significant risk from an inflating airbag. Only in a few extremely rare situations must an infant or child sit in the front, necessitating an on/off switch. If a driver does get a switch, it should be used to turn off the airbag only when an infant or child must ride in front.

Vehicles: Vehicles without rear seats are permitted to have an on/off switch installed for the passenger airbag; this includes some pickup trucks and some small cars.

Brochure: Need an airbag on/off switch — probably not

12 Has the Institute crash tested vehicles with side airbags?

Yes. In 2003 the Institute began a program of side impact crash tests for passenger vehicles. In the results so far, all of the good performers were equipped with side airbags that protect the head. But having side airbag protection for the head does not guarantee good performance; vehicles also need side structures that resist major intrusion into the occupant compartment.

13 Is there new airbag technology coming?

Airbag technology is under continuous development. For example, a safety belt airbag has been developed that would provide protection for all occupants in a crash; it works by inflating the torso portion of the belt. A pedestrian airbag has been developed to deploy on the outside of a vehicle — airbags are installed at each windshield pillar to provide head protection to a struck pedestrian.

14 Is it advisable to use airbags from salvaged vehicles to repair other vehicles?

No. Airbag modules recovered from salvaged vehicles should not be used to repair other vehicles. The designs of the airbag systems in most cars have been improved in recent years (sometimes improved several times). Therefore, matching a correct airbag module to a car that is being repaired is not straightforward. Another issue involves the possibility of water damage. There is a risk that salvaged airbag modules will be from vehicles that have been in floods. Water damage can adversely affect airbag inflation characteristics. This problem may also arise if a salvaged airbag is directly exposed to water after being removed from a car. Finally, the widespread use of salvaged airbags for repairs is likely to exacerbate the already significant problem of airbag theft. Thieves have long targeted specific car parts such as radios and wheel covers, but in recent years they've developed a black market for airbags, which can be sold at a low price to unethical repair-shop owners who then charge customers the standard price for a replacement airbag.

15 Do motorcycles have airbags?

A frontal airbag is offered as an option on 2006 and later models of Honda's Gold Wing touring motorcycle. Honda's airbag is designed to deploy in severe frontal impacts and absorb some of the forward energy of the driver.

Honda Gold Wing touring motorcycle with frontal airbag

 

References

¹Casey, M. and Montgomery, R. 2007. Front airbags don't inflate in hundreds of head-on crashes. The Kansas City Star, October 22.

²Braver, E.R.; McCartt, A.T.; Sherwood, C.P.; Fraade-Blanar, L. and Scerbo, M. 2009. How often do front airbags fail to deploy in fatal frontal crashes? Paper to be presented at the 21st ESV Conference June 15-18, 2009, Stuttgart, Germany. Available: www.iihr.org/research/topics/pdf/r1116.pdf

³National Highway Traffic Safety Administration. 2009. Special Crash Investigations — Counts of frontal air bag related fatalities and seriously injured persons. Washington, DC: US Department of Transportation.

⁴Kahane, C.J. 2004. Lives saved by the federal motor vehicle safety standards and other vehicle safety technologies, 1960-2002: passenger and light trucks. Report no. DOT HS-809-833. Washington, DC: National Highway Traffic Safety Administration.

⁵McCartt, A.T. and Kyrychenko S.Y. 2007. Efficacy of side airbags in reducing driver deaths in driver-side car and SUV collisions. Traffic Injury Prevention 8:162-70.

⁶Arbogast, K.B.; Durbin, D.R.; Kallan, M.J.; and Winston, F.K. 2003. Effect of vehicle type on the performance of second-generation airbags for child occupants. Proceedings of the 47th Annual Conference of the Association for the Advancement of Automotive Medicine, 85-99. Barrington, IL: Association for the Advancement of Automotive Medicine.

⁷Kahane, C.J. 2006. An evaluation of the 1998-1999 redesign of frontal air bags. Report no. DOT HS-810-685. Washington, DC: National Highway Traffic Safety Administration.

⁸Braver, E.R.; Scerbo, M.; Kufera, J.A.; Alexander, M.T.; Volpani, K; and Lloyd, J.P. 2008. Deaths among drivers and right-front passengers in frontal collisions: redesigned air bags relative to first-generation air bags. Traffic Injury Prevention 9:45-58.

⁹Ferguson, S.A. and Schneider, L.W. 2008. An overview of frontal airbag performance with changes in frontal crash-test requirements. Washington, DC: Blue Ribbon Panel for the Evaluation of Advanced Technology Airbags.

¹⁰Arbogast, K.B. and Kallan, M.J. 2007. The exposure of children to deploying side airbags: an initial field assessment. Proceedings of the 51th Annual Conference of the Association for the Advancement of Automotive Medicine, 245-59. Barrington, IL: Association for the Advancement of Automotive Medicine.