An airbag is a gas-inflated cushion built into the steering wheel, dashboard, door or roof of a car that uses a crash sensor to trigger rapid expansion, to protect occupants from the impact of an accident. The airbag slows a passenger’s speed in a moving car to a stop.

How an airbag works

The airbag is made of a thin nylon fabric and folded into the steering wheel or dashboard during the manufacturing process.

If the car is involved in a hard collision, a sensor triggers the bag to inflate. A signal is sent to the inflator unit within the airbag and an igniter starts a rapid chemical reaction to generate mainly nitrogen gas to fill the airbag.

Because vehicles change speed so quickly in a crash, airbags must inflate rapidly to reduce the risk of the occupant hitting the vehicle's interior. All that happens in 0.05 seconds – faster than the blink of an eye.

Airbag deployment is frequently accompanied by the release of a powdery substance, either cornstarch or talcum powder, used by the airbag manufacturers to keep the bags pliable while in storage. Almost immediately, the airbag is deflated as the gas dissipates quickly through tiny holes in the bag.

Safety concerns

Because of the strong force at which an air bag inflates (about 350 kmh), contact with a deploying airbag may cause minor injuries like bruises.

That is why objects – especially hard, heavy or sharp ones – must never be attached to the part of the steering wheel or dashboard containing an airbag, since they can be propelled into you with great force by an inflating airbag, potentially causing serious injuries.

The airbag is meant to be used in tandem with seat belts. Seat belts are still necessary because the airbag won’t inflate during a slight collision. And only seat belts can help you in side crashes, rear-end collisions and secondary impacts.

Researchers have determined that the risk zone for the airbag on the driver’s side is the first 5cm to 8cm of inflation. So positioning yourself 25cm away from the steering wheel should give you a clear margin of safety.

An airbag can seriously injure or even kill an unbuckled child who is sitting too close to the part of the car containing the airbag, or is thrown towards the dashboard during a collision. Thus, it is important that younger children should sit in the rear seat, wearing the proper child restraints.

New airbags

Some new vehicles come equipped with side torso and side curtain airbags to help protect the head and chest in a side-impact crash. These airbags are usually located in the seat or door, and inflate between the seat occupant and the door.

More advanced technologies are being developed for airbag systems to automatically determine if at all, and with what level of force, the driver and passenger frontal air bags will inflate. Sensors will detect the severity of the crash, the size and posture of the vehicle occupant, belt usage, and how close that person is to the airbag.