Inflating in a fraction of a second immediately after a serious crash occurs, airbags are cushions that protect occupants from hitting the interior parts of their vehicles or, in some cases, objects outside the vehicle (for example, other vehicles or trees). The instant a crash begins, sensors begin to measure impact severity. If the crash is severe enough (that is, at or above the airbag deployment threshold), the sensors signal inflators to fill the bags with harmless gas. The bags fill in a fraction of a second to restrain occupants.

There are several types of airbags. Most vehicles have airbags that deploy in frontal crashes to protect front-seat occupants. These airbags are stowed in the steering wheel for the driver. Frontal airbags for the passenger are stored in the instrument panel.

Video: frontal driver airbag deploying from the steering wheel

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. There are two major categories of side airbags: those designed to protect only the torso (chest, abdomen, and pelvis) and those that also include head protection. Side airbags also may deploy in frontal or rollover crashes to help prevent partial or full ejection.

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

 

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People who use their safety belts may think they do not need airbags. But they do. In serious frontal crashes, the occupant compartment and the people riding inside do not stop immediately, but continue moving forward as the vehicle's front end crushes. 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 people hit these surfaces hard, they can sustain serious or fatal injuries to the head and chest. By keeping people from hitting these interior surfaces, airbags are providing important additional protection that is maximized when used in conjunction with safety belts. The additional protection of airbags can be even more important in side impacts where a properly belted occupant can still be struck by an intruding vehicle or object. 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 striking vehicle or a tree that's being struck.

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

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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. But airbags began to be a popular feature beginning with 1990 models when manufacturers were required to install either automatic safety belts or airbags on new passenger cars. By the 1995 model year, virtually all cars and many light trucks were equipped with driver airbags. By the 1997 model year, most also had passenger airbags.

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Side airbags are not required by the government or regulated by the National Highway Traffic Safety Administration (NHTSA). They are, however, offered as either a standard or optional feature by many vehicle manufacturers. Seventy percent of all 2006 passenger vehicle models offered head-protecting side airbags (39 percent standard equipment, 31 percent optional equipment). In September 2007, NHTSA issued new side-impact safety requirements that likely will result in more manufacturers voluntarily equipping their vehicles with side airbags, including side curtain airbags and thorax airbags. The new standard requires automakers to provide head protection in side-impact crashes but doesn't mandate side airbags.

Models with side airbag head protection systems

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Airbags deploy only when they might be needed to prevent serious injury. Frontal driver and passenger airbags are designed to inflate in moderate to severe frontal crashes equivalent to hitting a solid barrier at 10-12 mph. Some manufacturers use different inflation thresholds depending on whether people are using their safety belts. Thresholds of 10-12 mph typically are used for unbelted occupants, but thresholds are higher — about 16 mph — for belted occupants because the belts alone are likely to provide adequate protection up to these moderate speeds.

Side airbags are designed to protect an occupant's head and/or neck from striking objects inside or outside the vehicle in the event of a side impact crash. Because of the small amount of space between an occupant's head and the side of the vehicle, these airbags must deploy very quickly to cushion the occupant from any intruding vehicle or object such as a tree. Sensors detect when a crash is severe enough for deployment. 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.

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Frontal airbags: NHTSA estimates that more than 22,000 people are alive today because of frontal airbags.¹ Among belted occupants in frontal crashes, deaths in frontal airbag-equipped cars are 26 percent lower among drivers and 14 percent lower among passengers compared with vehicles without frontal airbags. Deaths among unbelted occupants in frontal crashes are reduced by 32 percent for drivers and 23 percent for passengers.² NHTSA estimates that the combination of an airbag plus lap/shoulder belt reduces the risk of serious head injury by 85 percent compared with a 60 percent reduction for belts alone.³

Side airbags: Analyses of the efficacy of side airbags suggest they have reduced deaths among passenger car drivers involved in driver-side collisions by about 37 percent when the side airbag included head protection and by 26 percent when the side airbag was designed to protect only the torso. Death risk for drivers of SUVs was reduced by 52 percent with head-protecting side airbags and by 30 percent with torso-only airbags.⁴

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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. Since 1990, deaths attributable to airbag inflation in low-speed crashes numbered more than 270 according to NHTSA. Approximately 67 percent of motorists killed by airbags have been passengers, and more than 90 percent of the passenger airbag fatalities have been children and infants, most of whom were unbelted or in rear-facing restraints that placed their heads close to the deploying airbag. Among the adult driver and passenger deaths, about three-quarters were women. More than 80 percent of those killed were unbelted or improperly restrained, and nearly 90 percent of deaths occurred in vehicles manufactured before 1998.

In 1997, the federal government set rules allowing manufacturers to reduce the energy (or power levels) of frontal airbags. Indications are that newer airbag designs 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 cars and minivans were half as likely to sustain significant injury compared with children in pre-1998 cars and minivans.⁵ Another study concluded that 1998 and 1999 model passenger vehicles appear to be providing improved protection in frontal crashes compared with vehicles manufactured prior to 1998 with the exception of pickups, which had an increased risk. When pickups were excluded, there was an 11 percent decrease in driver fatality risk in frontal crashes among other passenger vehicles combined.⁶ A study by NHTSA in 2006 reported that redesigned airbags reduced fatality risk to child passengers by 45 percent without changing the beneficial effects for adults.⁷

Like frontal airbags, side airbags have the potential to cause injury. However, side airbags typically are smaller and involve less deployment energy than frontal airbags. To date, there has been only one serious injury reportedly due to side airbag inflation. This involved an elderly male driver who suffered multiple rib fractures. His vehicle was equipped with door-mounted side airbags designed to protect the chest only.

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Anyone on top of or very close to a frontal airbag as it begins to inflate may be injured. Most deaths caused by frontal airbags involve people who were unbelted or improperly belted. Unbelted occupants, especially passengers, 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, their airbags as they begin to inflate. Short and elderly drivers can be especially vulnerable to inflation injuries from frontal airbags because they tend to sit close to the steering wheel. Infants in rear facing restraints are at a very high risk, because the infants' heads are close to the deploying airbag.

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The first step in preventing injuries from inflating airbags is to use a safety belt and maintain a proper seating position. Other important precautions include:

Drivers: It is recommended that drivers sit with their chests at least 10 inches away from the center of the steering wheel. Many of the 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 might be a consideration. If drivers still cannot comfortably sit back and away from the steering wheel, an airbag on/off switch may be considered.

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

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. Rear seats always have been safest for infants and children, even before airbags, and now this is more important. Because of public education that children are safer in rear seats, and laws in 14 states requiring it, children increasingly are sitting in these positions. In 2005, 25 percent of passenger vehicle child occupant deaths occurred in the front seat, down from 46 percent in 1975.

Rear-facing infant restraints should not be used in front seats with frontal airbags because this puts an infant's head too close to the airbag. The forces of the inflating airbag against the back of a rear-facing restraint can cause serious, even fatal, head injuries. Virtually all older children killed by frontal airbags were either unbelted or improperly belted and moved too close to the airbag during pre-impact braking. 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. Children younger than 12 should always be restrained in rear seats. Only if an adult is transporting too many children to put them all in the back seat should a child ride up front. Then the seat should be all the way back and the child should be securely buckled in a lap/shoulder belt and sitting back in the seat. Leaning forward to fiddle with radio dials, for example, can put a child at risk from an inflating airbag. If a driver routinely transports too many kids to put them all in back and worries about keeping a child in the front seat sitting back, away from the airbag, an airbag on/off switch may be considered.

There are a few instances in which a child can be seated in front in an airbag-equipped car. For example, some vehicles have sensors in specially designed restraints and passenger seats that detect rear-facing infant restraints and automatically switch off airbags on the passenger side. Also, if a passenger airbag is labeled "advanced" (meaning it will deploy with low force or deactivate if a child is in the passenger seat) or if the airbag has been turned off manually, a child may sit in front.

The risk of injury from a side airbag is extremely low for adults or children who are properly restrained. 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 side door or lying down on a seat with their heads near the door or sides of a vehicle are at high risk of injury in the event of a side impact.

Concerns about potential injuries, particularly to small children who might lie down in the seat or assume other positions against a deploying side airbag, led to the formation of the Side Airbag Out-of-Position Injury Technical Working Group. 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 guide, Buying a Safer Car, almost 80 percent of vehicles have side airbags designed according 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: Some women late in pregnancy may not be able to get their abdomens away from the steering wheel. There can be a risk of fetal injury from a frontal airbag if it inflates. Even without the airbag, there is a risk of fetal injury from hitting the steering wheel. Ideally, women at this stage of pregnancy should avoid driving. However, if they must drive the combination of properly positioned safety belts and airbags offers the best protection.

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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. (The on/off switches will be allowed 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: Drivers should always sit at least 10 inches away from the steering wheel; sitting closer puts them at risk of injury. Most drivers, including short women, usually can sit comfortably 10 inches from the steering wheel. Pedal extenders may be considered if a driver is unable to sit back far enough. If a driver has tried and still is unable to get back and away from the steering wheel, an airbag on/off switch could be considered. Most 1998 and newer vehicles, however, have redesigned airbags with less powerful inflators that reduce serious injury risk. In these vehicles, there probably is no need to get an on/off switch, even if a driver cannot get 10 inches from the steering wheel. If an on/off switch is considered, remember that without an airbag, a driver's face is likely to hit the steering wheel in a serious frontal crash. Once the risks of deactivating an airbag are understood, the benefits should be weighed against these risks.

Passengers: Properly restrained adults sitting back in the seat are not at significant risk from an inflating airbag, but there is a risk for children and infants in the same position. Children are safest when properly restrained in rear seats. Rear-facing infant seats should never be placed in the front seat with an airbag. Infants with medical conditions that require constant observation may need to ride in the front, and then an airbag switch would be needed. If a driver transports too many children to put them all in back seats, an older child should ride up front only with the seat all the way back, secured in a lap/shoulder belt and sitting back in the seat. 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. It should be noted that 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.

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In this type of crash, typically only the side airbag on the driver's side will deploy as well as the rear-seat side airbag on the same side, if present. If the car is hit on the passenger side, the front and rear side airbags on the passenger side will deploy. On rare occasions, if a crash is sufficiently severe with multiple impacts, the side airbags on the nonstruck side might also deploy.

Some manufacturers are designing side airbags to deploy in some frontal crashes as well as side impacts. The side airbags can help keep occupants' heads inside the occupant compartment or from hitting hard surfaces inside the vehicle. Conversely, frontal airbags may deploy to help protect occupants in side impacts. For example, if a vehicle is moving forward at the time of a side impact, the frontal airbags can help prevent serious injuries.

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Yes. In 2003 the Institute began a program of side impact crash tests to provide consumers with comparative evaluations of passenger vehicles. The test represents what happens when a passenger vehicle is struck in the side by a pickup truck or SUV at 31 mph. In the results so far, all of the good performers were equipped with side airbags to 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.

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Airbag technology is under continuous development. For example, an inflatable curtain has been designed that would deploy from the roof in the event of a rollover crash to protect occupants' heads and prevent ejection. Another airbag has been developed that would inflate under the front edge of the seat cushion during a frontal crash, keeping motorists upright and preventing them from submarining under their safety belts. A safety belt airbag also 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. Some manufacturers also provide knee airbags, which usually are 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.

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A frontal airbag is offered as an option on 2006 and later models of Honda's Gold Wing touring motorcycle, but this is the only motorcycle with an airbag as available equipment. Honda's airbag is designed to deploy in severe frontal impacts, helping to absorb some of the forward energy of the rider.

Honda Gold Wing touring motorcycle with frontal airbag

 

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