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 side airbags separate from those in the front seat.

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

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.

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. Airbags became popular in the early 1990s. 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. Therefore, most new vehicles had dual frontal airbags even before they were required by government.

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-five percent of all 2008 passenger vehicle models offered side airbags (69 percent as standard equipment, 16 percent as optional equipment). Of 2008 model year vehicles, side airbags were provided as standard or optional equipment in 92 percent of cars, 100 percent of SUVs, and 56 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

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. Some manufacturers use 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.

New "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 (i.e. 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.

Frontal airbags: NHTSA estimates that as of July 1, 2008 more than 27,000 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.¹

In frontal crashes, airbags alone 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) as 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.²

Side airbags: Analyses of the efficacy of side airbags with head protection showed a 37 percent reduction in a passenger 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.³

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.⁴ 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.⁵ 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.⁶ In 2008, a blue ribbon panel of highway safety experts, insurers, automakers, and highway professionals 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.⁷

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.

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. Approximately 68 percent of people killed by frontal airbags have been passengers. More than 90 percent of these 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.¹ More than 80 percent of deaths 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, their 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: To date, only one serious injury due to side airbag inflation has been reported. This involved an elderly male driver who suffered multiple rib fractures. His vehicle was equipped with door-mounted side airbags designed to protect the torso only.

As of December 2006, no children are known to have been seriously or fatally injured by a side airbag, out-of-position children may be at increased risk of injury. According to NHTSA's Special Crash Investigations, only one child in its sample of crashes 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. 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.⁸ Out-of-position children may be at increased risk of injury. However, for vehicles conforming to the test protocol of the Side Airbag Out-of-Position Injury Technical Working Group (TWG), risk remains low.

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 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 front 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.

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 high 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, 90 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. Ideally, women in the late stages of pregnancy should avoid driving. If they must drive, the combination of properly positioned safety belts and airbags offers the best protection.

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

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 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.

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. Rear seat airbags specifically designed to protect back passengers in rear impact crashes are also under development.

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