Airbag Basics

Written by Staff Writer

The first patent on airbags was filed during World War II and was originally designed as an inflatable crash-landing device for airplanes. When airbags for automobiles were introduced in the early 1990's, there was considerable debate on how fast they should deploy. Those who argued that the bag should deploy rapidly enough to protect unbelted occupants of the front seat won the day. The force this requires is a problem for smaller people and people who might be positioned close to the airbag — primarily infants, children, and adults under five feet, five inches tall. Infants and small adults should be seated in the rear of the vehicle equipped with dual airbags protecting the front seat.

Please note that as you age, you become smaller and more fragile. This is a natural process of aging. If you must drive, realize that sitting too close to an airbag, either in the driver or passenger seat could injure you if the airbag inflates in a crash. Being belted in and having the minimum 10 inches of space between you and the airbag becomes more important the older you get. If this is not possible, they should position their seat as far back from the airbag as possible.

The airbag module contains both an inflator unit and the lightweight fabric airbag. The airbag system consists of three basic parts: (1) An airbag module, (2) crash sensors, and (3) a diagnostic unit. Some systems may also have an on/off switch, which allows the airbag to be deactivated. However, the laws governing deactivation are very strict and are discussed in 'Can an airbag be disabled?'

The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or door.

The sensor is the device that tells the bag to inflate. Inflation happens when there is a crash force equal to running into a brick wall at 10 to 15 miles per hour. A mechanical switch is flipped when there is a mass shift that closes an electrical contact, telling the sensors that a crash has occurred. The sensors receive information from an accelerometer built into a microchip.

The airbag's inflation system reacts combining sodium azide with potassium nitrate which produces nitrogen gas. Hot blasts of the nitrogen inflate the air bag. Now you would think this process would produce some very dangerous chemicals; however, the powdery substance released from the airbag is nothing more than regular cornstarch or talcum powder.

Once the bag has been inflated and the bag has done its job, the gas quickly dissipates through tiny holes in the bag, thus deflating the bag so you can move.

For cars that have airbags, where should your hands grip the steering wheel?

The AAA has suggested modifying the steering wheel gripping position in airbag equipped cars from ten and two o'clock to nine and three or even eight and four o'clock to allow room for the airbag to deploy.

Can a new vehicle be purchased without airbags?

In the 1980s, the first widespread commercial application of air bags appeared in automobiles. Starting in model year 1998, all new passenger cars were required to have dual (driver and passenger side) airbags. Starting in model year 1999, all new light trucks were required to have dual airbags.

Can an airbag be disabled?

Disabling an airbag is difficult and can be dangerous. Federal law prohibits dealers, repair shops, etc. from disabling airbags. However if necessary, you can contact and obtain permission from the National Highway Traffic Safety Administration (NHTSA) to disable an airbag. Some vehicles, such as taxicabs, may include an on/off switch for the passenger side airbag.

Do airbags save lives?

Yes. NHTSA research reported that an estimated 2,488 lives were saved by airbags in 2003. Side airbags with head protection are highly effective, according to the IIHS. They reduce deaths of drivers of passenger cars who are struck on the driver side by about 45%.

Do I need to wear my safety belts if I have airbags in my car?

Airbags are called supplemental restraints because they are designed to work best in combination with safety belts. A safety belt should always be worn whether or not the vehicle has an airbag. Even as technology advances, airbags still are only effective when used with a seat belt. All new passenger cars, light trucks and vans are equipped with both driver and passenger front airbags.

Airbags are not designed to deploy in all crashes. Most are designed to deploy in moderate to severe frontal crashes. If the vehicle is struck from the side or rear, side airbags offer some protection. Side airbags, which protect the chest and abdomen, are less effective but still reduce deaths by about ten percent. Airbags, combined with lap/shoulder belts, are the most effective safety protection available for passenger vehicles. By 2003, more than 146 million passenger vehicles on the road were equipped with airbags, including 126 million with dual airbags.

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This article was written by SafeMotorist.com defensive driving staff writers and reviewed for accuracy by defensive driving instructors. All articles are based on current traffic laws and defensive driving practices. This article is intended for educational purposes only, and should not be taken as legal advice or literal interpretation of any specific traffic law.