April 2015

  1. How do airbags work?

    Airbags are inflatable 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, the sensors signal inflators to fill the bags with gas in a fraction of a second. The speed of a deploying airbag can reach up to 200 mph. Airbags are designed to offer the most protection when occupants are wearing safety belts and sitting properly in the seat. To determine the locations of airbags within a vehicle, look for the word "airbag" or "SRS" (supplemental restraint system) stamped into plastic or stitched into fabric in the vehicle interior.

    Airbag systems do not typically require regular maintenance. A properly functioning airbag can last the lifetime of the car unless it deploys in a crash. A demonstration test conducted by the Institute showed that the original frontal airbags in a 1973 Chevrolet Impala deployed properly more than 20 years after the car was built.

    The airbag light on the instrument panel indicates whether the airbags are functioning properly.  If the airbags are working properly, the warning light illuminates for a few seconds when the ignition is switched on. If the airbag warning light is flashing, remains illuminated with or without a warning beep or doesn't illuminate during the ignition on cycle, the airbag requires maintenance and should be taken to service center.

    Airbags must be replaced after deployment in a crash. Airbags should be replaced at a repair shop that uses original equipment manufacturer (OEM) replacement parts to ensure that the new airbag is not counterfeit.

    Airbag marker tag

    Airbag indicator stitched into the seatback


    Airbag marker stamp

    Airbag indicator stamped into the interior trim near the roof


  2. What kinds of airbags are common in today's vehicles

    Frontal airbags:

    Frontal airbags are designed to inflate in moderate to severe frontal crashes to prevent a person’s head and chest from contacting hard structures in the vehicle known to cause serious injuries. Typically frontal airbags deploy within the first 50 milliseconds (0.05 seconds) of impact. They offer the most protection when occupants are wearing safety belts and sitting properly in the seat but are designed to provide protection for all occupants. Newer airbags have advanced features that include a safety belt sensor and an algorithm to decide whether to deploy the bag in a given crash, depending on whether people are using safety belts. Typically a front airbag will deploy for unbelted occupants when the crash is the equivalent of an impact into a rigid wall at 10-12 mph. Most airbags will  deploy at a higher threshold  — 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 movement during the crash.

    The driver airbag is located in the steering wheel. The passenger airbag is located in the instrument panel. Some manufacturers provide supplemental 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 movement of the occupant's lower body. Seat cushion airbags serve a similar purpose as the knee airbag, but are located in the seat pan instead of the instrument panel.

    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.

    Front dual airbag system

    Front dual airbag system


    Knee airbag

    Knee airbag


    Front dual airbag system
    Ford press site

    A space-saving knee airbag design, developed by Ford, deploys between the instrument panel structure and outer cover


    Seat cushion airbag
    Toyota press site

    Seat cushion airbag


    Side airbags: 

    Head- and chest-protecting side airbags are designed to inflate in side crashes to prevent people’s heads and chests from contacting intruding parts of vehicle side structure, a striking partner vehicle or an object such as a tree or pole. Such contact can seriously injure properly belted occupants. A head-protecting side airbag is particularly important because it may be the only thing between the occupant’s head and the striking vehicle, since window glass can shatter in a crash. Because of the small space between an occupant and the side of the vehicle, side airbags must deploy very quickly, typically within the first 10-20 milliseconds of a side crash. Deployment thresholds can be as low as 8 mph for narrow object crashes (e.g., trees and poles) and 18 mph for the more widely distributed side impacts (vehicle-to-vehicle crashes). Several auto manufacturers deploy the side airbags in frontal crashes to help control occupant movement.

    Torso-protecting side airbags typically deploy from the seatback to provide a cushion between the occupant’s chest and the intruding door structure. Some early models deployed from the door trim. Newer models deploying from the seat typically extend downward to provide additional protection to the pelvis. Torso airbags can also be found in rear outboard seating positions. Head-protecting curtain side airbags are typically located in the roof-rail, and deploy downward to cover the window frame. These airbags may extend head protection into the rear seating areas. Often both the seat-mounted torso airbag and curtain airbag are installed to provide head and torso protection. Another design providing protection for the head and torso is a combination bag, which deploys from the seatback and extends upward to cover both the torso and head. Regardless of type and location, side airbags cushion and spread the load of these impacts to prevent any part of the body from sustaining concentrated impact forces.

    In 2007, the federal government introduced a new side-impact regulation that does not specifically mandate side airbags but requires a certain level of head and torso protection for all occupants, which is typically achieved with side airbags. All vehicles must comply by the 2017 model year. The vast majority of new passenger vehicles come with side airbags as standard equipment.

    Side head airbag

    A head-protecting curtain airbag is often the only barrier between the dummy's head and the striking vehicle


    Side head/torso airbag

    A combination airbag, deploying from the seatback, provides protection for the head and torso


    Side head/torso airbag

    A head-protecting curtain airbag and seat-mounted torso-protecting airbag


    Side head/torso airbag

    A head-protecting curtain airbag and seat-mounted torso and pelvis-protecting airbag


    Side head/torso airbag

    A head-protecting curtain airbag deploying from the door and seat-mounted torso and pelvis-protecting airbag


    Rollover airbags: 

    Rollover airbags are a special type of side curtain airbag that deploy in response to sensors that measure a vehicle's sideways movement and tilting. They typically inflate within the first 10-20 milliseconds of a side or rollover crash and can remain inflated longer than regular side curtain airbags (10 or more seconds) to protect during multiple-roll crashes. While rollover airbags look like regular side curtain airbags, they are larger, covering more of the window, and stiffer to prevent ejection of the occupant.

    The government doesn’t specifically require rollover airbags, but automakers are expected to use them to comply with a new federal safety standard intended to prevent occupant ejection through side windows. This new standard began a phase-in with model year 2014, and all passenger vehicles must comply by the 2018 model year.

    rollover
    rollover

    A rollover airbag used to meet the federal safety standard to prevent occupant ejection remains inflated for more than 10 seconds, covering multiple rolls of the vehicle and keeps occupants contained inside


  3. What are the recent airbag innovations?

    As technology advances, manufacturers are finding new ways to integrate airbags into vehicles. The following airbags are not as common but are present in a limited number of production vehicles.

    Inflatable safety belts:

    In 2012 Ford rolled out an inflatable safety beltaimed at reducing rear-seat injuries. The inflatable safety belt is intended to enhance protection for adult-sized occupants and children using booster seats or safety belts alone. In a crash, the shoulder belt inflates, distributing crash forces across the torso and chest. The inflatable belts are currently available as optional equipment in the outboard second-row seating positions of several Ford and Lincoln vehicles. The Mercedes-Benz S-Class comes with standard inflatable belts.

    Ford inflatable safety belt
    Ford press website

    Ford inflatable safety belt


    Rear window curtain airbag:

    Beginning with the 2012 model year, the Scion iQ microcar has a rear window curtain airbag as a standard feature. The airbag is intended to prevent direct contact of the back seat occupants with vehicle parts and broken glass in the event of a rear crash. The airbag deploys in front of the rear windshield and around the rear seat head restraints.

    Rear curtain airbag

    Rear curtain airbag


    Front center airbag:

    General Motors has developed a front center airbag intended to prevent front passengers from colliding with each other during side-impact crashes and to maintain occupant position in far-side or rollover crashes. Starting with the 2013 model year, the airbag is available in the Buick Enclave, GMC Acadia and Chevrolet Traverse. Toyota has developed a rear center airbag that deploys from the center console. It’s meant to do the same thing as the GM front center bag, only in the back seat. Toyota is launching this airbag in a new model available in Japan.

    GM front center airbag
    GM press release

    GM front center airbag


    External hood airbag:

    Volvo has developed the first hood airbag designed for pedestrian protection. When a collision with a pedestrian is detected, an external airbag deploys from under the hood and covers the hard parts of the windshield and the A-pillar, locations that pedestrians frequently strike. The pedestrian hood airbag is standard on the Volvo V40 available only in Europe, starting with the 2013 model year.

    Hood airbag
    Volvo press site

    Volvo hood airbag


    Motorcycle airbag:

    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. No studies have been conducted on the real-world effectiveness of motorcycle airbags.

    Motorcycle airbag
    Honda media

    Honda Gold Wing touring motorcycle
    with frontal airbag


    Bicycle helmet airbag:

    A bicycle helmet airbag has been developed in Sweden by Hovding. The airbag for bicyclists is meant to be used instead of a traditional helmet. It is designed to deploy out of a collar worn around the neck when sensors indicate abnormal movement of the cyclist indicating a crash. The airbag deploys in 0.1 of a second. No studies have been conducted on the real-world effectiveness of the helmet airbag.

    bike
    Hovding media

    Hovding helmet airbag


  4. How effective are airbags in reducing the risk of death in crash?

    Frontal airbags:

    NHTSA estimates that as of 2012, 42,856 lives have been saved by frontal airbags. Kahane, C.J. 2015. Lives saved by vehicle safety technologies and associated federal motor vehicle safety standards, 1960 to 2012 - passenger cars and LTVs - with reviews of 26 FMVSS and the effectiveness of their associated safety technologies in reducing fatalities, injuries, and crashes. Report no. DOT HS-812-069. Washington, DC: National Highway Traffic Safety Administration. In frontal crashes, frontal airbags reduce driver fatalities by 29 percent and fatalities of front-seat passengers age 13 and older by 30 percent. The fatality reduction in frontal crashes is larger for belted drivers (52 percent) compared to unbelted drivers (21 percent). NHTSA estimates that the combination of an airbag plus a lap and shoulder belt reduces the risk of death by 51 percent, compared with a 45 percent reduction for belts alone in frontal crashes. 

    Institute researchers found an overall reduction in fatal crash risk associated with newer depowered airbags compared with earlier designs. Braver, E. R.; Kyrychenko, S.Y.; and Ferguson, S.A. 2005. Driver mortality in frontal crashes: comparison of newer and older airbag designs. Traffic Injury Prevention 6(1):24-30. A 2006 NHTSA study reported that redesigned airbags reduced fatality risk to child passengers by 45 percent, compared with pre-1998 airbags – without reducing the benefits for adults. Kahane, 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.

    Side airbags: NHTSA estimates that as of 2012, 2,252 lives have been saved by side airbags. Kahane, C.J. 2015. Lives saved by vehicle safety technologies and associated federal motor vehicle safety standards, 1960 to 2012 - passenger cars and LTVs - with reviews of 26 FMVSS and the effectiveness of their associated safety technologies in reducing fatalities, injuries, and crashes. Report no. DOT HS-812-069. Washington, DC: National Highway Traffic Safety Administration. Side airbags with head protection reduce a car driver's risk of death in driver-side crashes by 37 percent and an SUV driver's risk by 52 percent, an Institute analysis of U.S. crashes showed. McCartt, 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(2):162-70. Side airbags designed to protect only the torso reduce fatality risk by 26 percent for car drivers and by 30 percent for SUV drivers. A study of crashes in Australia found that side airbags with head and torso protection reduce a car driver's risk of death or injury in driver-side crashes by 41 percent. D'Elia, A.; Newstead, S.; and Scully, J. 2013. Evaluation of vehicle side airbag effectiveness in Victoria, Australia. Accident Analysis and Prevention 54:67-72. Similar trends were found in a NHTSA study focusing on the fatality risk to drivers and right-front-seat passenger vehicles involved in nearside crashes. Curtain and torso airbags reduce the risk of death by 31 percent, and combination head/torso airbags reduce the risk by 25 percent. Kahane, C.J. 2014. Updated estimates of fatality reduction by curtain and side air bag in side impacts and preliminary analyses of rollover curtains. Report no. DOT HS-811-882. Washington, DC: National Highway Traffic Safety Administration. The death reduction was lower in vehicles equipped only with a curtain airbag (16 percent) or only with a torso airbag (8 percent).

    The crucial role played by head-protecting side airbags is illustrated by the results of the Institute's side-impact crash tests, which measure how well passenger vehicles would protect occupants in a side crash. Since the program began in 2003, all the vehicles earning good ratings have been equipped with side airbags that protect the head. However, airbags alone aren't enough. Vehicles also need side structures that resist major intrusion into the occupant compartment.

  5. Can airbags cause injury?

    Occasionally, the energy required to quickly inflate airbags can cause injury to people sitting or thrown too close to the airbag before it deploys. This was a serious concern with the first generations of frontal airbags, which deployed with greater force. NHTSA estimates that during 1990-2008, more than 290 deaths were caused by frontal airbag inflation in low-speed crashes. 1 Nearly 90 percent of the deaths occurred in vehicles manufactured before 1998, and more than 80 percent of people killed were unbelted or improperly restrained. Most of the deaths were passengers, and more than 90 percent of those 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. Short and elderly drivers, who tend to sit close to the steering wheel, also were vulnerable to inflation injuries from frontal airbags.  However, thanks to advanced airbag government requirements, serious airbag injuries are becoming a thing of the past.

    In 1997, the federal government modified safety rules to encourage automakers to take energy out of frontal airbags. Depowering began with 1998 models. Manufacturers were required to demonstrate compliance with additional test conditions involving unbelted dummies to meet the new standard. In 2001, NHTSA issued a certified-advanced airbag rule that required more sophisticated airbags in all passenger vehicles by the 2007 model year. Advanced airbags modify deployment patterns if weight sensors detect a small driver or front-seat passenger or a child safety seat. These airbags can be suppressed altogether or deploy with less force when passengers are small or out of position, or if a crash isn't severe. They also can determine if occupants' safety belts are buckled and generally deploy at lower thresholds for people who aren't using belts or are sitting close to the airbag. Manufacturers have to pass a suite of tests using different-size dummies, belted and unbelted, in a variety of crash test speeds and configurations.

    Side airbags also can deploy with enough energy to cause injury, although they typically are smaller and deploy with less energy than frontal airbags. Injuries from contact with side airbag inflations in crashes have been documented, 7 but there is no indication that such injuries are common. A field study of children in side crashes found no increased risk of injury to children age 15 and younger associated with side airbag deployment. 8

    Faulty airbags also can injure people. The government issues recalls for vehicles with faulty airbag systems that result in increased risk of injury in a crash. Reasons can include failure to deploy, incorrect timing or energy of deployments, and defective parts. Recalled airbags should be replaced to ensure that occupants receive the optimal level of protection in a crash.

    See the NHTSA recall database to check your vehicle for recalls. The database also has information on service centers that are authorized to repair recalled vehicles free of charge.

    Counterfeit airbags also pose a risk of serious injury because they don't perform the same in a crash as original equipment manufacturer (OEM) parts. 14 Counterfeit airbags are replacement airbags that were never certified by the vehicle manufacturer as meeting the same standards as the vehicle’s original airbag. Vehicles that have never had an airbag replaced and vehicles in which airbags have been replaced at a repair shop associated with a new-car dealership are not at risk of having counterfeit airbags. Vehicles at risk are those that have an unknown repair history; a salvage, rebuilt or reconstructed title; low-cost replacement airbags purchased online; or airbags replaced at an independent repair shop and that cannot be verified as OEM replacement stock.

    Investigations conducted by NHTSA have shown that counterfeit airbags consistently malfunction. In some cases they simply fail to deploy; in other cases, metal shrapnel is released during deployment. NHTSA estimates that only 0.1 percent of the U.S. vehicle fleet has counterfeit airbags, and no serious injuries or deaths have been associated with them. Information about how to determine if a vehicle has a counterfeit airbag, along with a list of models for which counterfeit airbags are known to be available, can be found at safercar.gov.

  6. What can drivers and passengers do to prevent injuries from airbags?
    Vehicles provide optimal protection when occupants are belted and sitting in the proper position. Drivers and front-seat passengers should sit in the center of the seat upright against the seatback with feet on the floor. Arms and legs should never be resting against an airbag because the forces of a deploying airbag and the hot gases exhausted by the airbag may cause injury. 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. They should avoid driving whenever possible.
    Areas on or around airbags should be free of objects that can either alter the proper deployment of airbags or become dangerous projectiles within the vehicle. Aftermarket dash covers may block a frontal airbag and seat covers may block a seat-mounted side airbag from proper deployment or redirect the airbag in a way that is dangerous.

    Drivers: Drivers should sit with their chests at least 10 inches away from the center of the steering wheel. For shorter drivers with the seat positioned further forward, this can often be achieved by slightly reclining the seatback. Many newer airbags take into account seating position and deploy with less force if an occupant is sitting close. 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. The government allows installation of switches on vehicles manufactured before Sept. 1, 2015.

    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.

    Infants and children: How and where infants and children are restrained in a vehicle are critical factors in avoiding airbag-related injuries. 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. Seventeen states have provisions requiring children of various ages to be seated in the rear. Even if your state's law does not require children to sit in the rear, children 12 and younger should always sit restrained in rear seats.

    If an adult is transporting too many children for them all to sit safely and comfortably in the back, the youngest children should ride in the back. When a child does need to ride in the front seat, the seat should be as far back as possible and the child should be securely buckled in a lap/shoulder belt and sitting against the seatback. If a driver routinely has to put a child in the front seat of an older vehicle, an airbag on/off switch may be considered.

    Nearly all older children killed by frontal airbags were either unbelted or improperly belted. But even belted children can be at risk if they wiggle out of position or sit on the edge of the seat, putting the head too close to the airbag.

    Children should not lean against the door area where the airbag is stored because the initial deployment force may be harmful. With or without an airbag, children who lean against doors or lie down with their heads near the doors or sides of vehicles are at higher risk of injury in the event of a side impact. All vehicle manufacturers have committed to following a test protocol for designing side airbag systems that assures that the inflation injury risk is low, even for small children who might lie down or assume other positions against a deploying side airbag.

  7. Do frontal airbags ever fail to deploy when they're needed?

    An Institute study reviewed airbag deployment status for fatal frontal crashes ocurring between 1998 and 2006 contained in the National Automotive Sampling System/Crashworthiness Data System, a sample of tow-away crashes with detailed data from crash investigators. Braver, E.R.; McCartt, A.T.; Sherwood, C.P.; Zuby, D.S.; Blanar, L.; and Scerbo, M. 2010. Front air bag nondeployments in frontal crashes fatal to drivers or right-front passengers. Traffic Injury Prevention 11(2):178-87. Institute researchers estimated that 1-2 percent of frontal occupant deaths represented potential airbag system failures where deployments would have been expected. However, there are inherent uncertainties about whether or not airbags would be expected to deploy in some crashes. 

  8. Is it OK to use airbags from salvaged vehicles to repair other vehicles?

    When an airbag needs to be replaced, a new replacement airbag module from the original manufacturer of the vehicle should be used. However, when it’s not possible to buy a new airbag module, the Institute recommends that care be taken to identify a salvaged airbag module that has been inspected and certified. Certification documentation should include the vehicle identification number of the vehicle from which the airbag was removed, the airbag salvage date, storage location and shipment details. Buyers should check the NHTSA recall database for any recalls that may apply to the salvaged airbag.

    Processing salvaged airbag modules can present a number of difficulties. The designs of the airbag systems in most cars have been improved in recent years (sometimes several times). Therefore, there's a significant possibility of a mismatch between the salvaged airbag module and the vehicle being repaired. 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 or that the airbag module was exposed to precipitation while at the salvage facility. Water damage can adversely affect the way an airbag inflates. There is no standard method to test the functionality of salvaged airbags.