If airbags are so safe, why doesn't my car have more?

Protection ... or overkill? See more car safety pictures.
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The airbag was a major advance in automotive safety when it was first introduced in the 1970s. As you're probably aware, their use has only grown. Since the late 1990s, all vehicles produced in the United States must have both driver and passenger side front airbags. Today, we also have side curtain airbags, tubular airbags, even knee airbags. Some companies have even started testing exterior airbags to protect pedestrians. It seems as if we're not that far from a car's interior bursting into one giant inflated cushion on impact. Sounds good, but tradeoffs abound: How much extra weight and cost can you build into a new car?

To answer this question, you must first understand how airbags work. The basic front airbag is designed to slow the acceleration of a car's occupants during impact, reducing the forces acting on them and preventing injuries. Side airbags do the same thing, but they protect occupants from side impacts. Curtain or tubular airbags protect the head from slamming into the side; while airbags mounted in the seat or the door protect the pelvis.


Other airbags in development generally help to hold the occupants safely during crashes. Take the knee airbag, for example. Many cars have large padded knee bolsters that protect legs from crash impacts. However, a sudden stop sends a person's legs flinging forward. When they strike something, the force is concentrated on one area of the leg. The result can be a severe leg fracture and damage to the hips or pelvis. A knee airbag either replaces the bolster or sits behind it. On impact, the airbag inflates and presses the occupants' knees back against the lower part of the seat, keeping them safely in place. Other new airbag designs keep people from sliding down in their seats, or shift an occupant's position away from the impact [source: Moore].

Protection is a good thing, especially while driving; however, how much is too much? Can a car actually be too safe to drive? Let's find out on the next page.


Airbag Limitations

Side airbags were relatively new when this Lexus debuted in 2002.
Car Culture/Getty Images

Technically, there's no upper limit to the number of airbags you could place in a vehicle. A car could be designed with every interior surface ready to inflate during impact; however, that vehicle would be very expensive and very heavy. Cost and weight -- those are the two main limits to the use of airbags.

The installation of airbags costs money for both the materials and labor. Replacing an airbag that has already been deployed can cost anywhere from $500 to several thousand dollars. They cost significantly less when they're initially installed at the factory, but the cost adds up quickly as more and more airbags are added. For example, the side airbag option on a 2006 Ford Fusion adds almost $600 to the final cost of the car [source: CBS News].


Extra weight is another problem. Increased weight reduces fuel mileage. The U.S. Environmental Protection Agency estimates that each 100 lbs. of weight added to a car reduces mileage by two percent [source: Fueleconomy.gov]. While automakers don't typically release information about the weight of individual components, and an individual airbag doesn't weigh very much, multiple airbags can significantly increase overall vehicle weight. If you consider the airbag itself, the chemical propellants needed to inflate it, the wiring and sensors, plus the enclosures for all the components, you can see that filling a car with a bunch of airbags would hurt your fuel economy.

Sure, airbags may make your car slower and heavier, but there some definite advantages. We'll explore those on the next page.


Are we better off with airbags?

Airbags may have many advantages, but detractors abound.
Patti McConville/Photographer's Choice/Getty Images

There's really no debate -- airbags save lives and reduce the severity of injuries. Data based on crash testing and actual, real-world crashes, as well as studies by the Department of Transportation and the Insurance Institute for Highway Safety show that airbags improve safety [source: Insurance Institute for Highway Safety]. There's still a strong undercurrent of opposition to airbags, just as there was for mandatory seatbelts, but the data doesn't lie.

That's not to say that airbags are perfect. If used improperly, they can cause injury or death. Children in car seats should not ride in the front seat if the vehicle is equipped with an airbag, and drivers generally should not sit within ten inches of the steering wheel. Since 1990, 290 airbag-induced deaths have occurred; in the same time frame, however, airbags have saved more than 27,000 lives [source: Insurance Institute for Highway Safety]. Side airbags are even safer -- no one has ever been killed by one. Even in the worst cases (which can be counted on one hand) they only cause minor injuries. In addition, modern front airbags have a safer, two-stage design. In low-speed collisions, they inflate with less force, reducing the chance of injury if a child or smaller person is in the front seat.


The cost-effectiveness of airbags remains a topic of extensive debate. Several studies have attempted to tabulate the cost of producing and installing airbags, the cost of fuel associated with the extra weight and the cost of replacing used airbags. That total cost is then compared to a numeric figure representing the economic cost of deaths and injuries. The number that comes out ahead seems irrelevant when someone you know was saved from serious injury or death.

Indeed, airbags can even help save you money. Many insurance companies offer discounts for vehicles with certain safety features -- including airbags. This may seem counterintuitive, since the airbags add to the cost of repairing the vehicle. In fact, that extra cost often means the vehicle will be written off instead of repaired. Insurance companies also pay to cover medical bills resulting from injuries, and those costs far outweigh the airbag replacement price.

For more information about airbag safety and development, follow the links on the next page.


Lots More Information

Related HowStuffWorks Articles

More Great Links


  • CBS News. "Ford Fusion Flunks Crash Test." March 6, 2006. (9/25/2008) http://www.cbsnews.com/stories/2006/03/06/business/main1371742.shtml
  • Environmental Protection Agency. "Driving More Efficiently." (9/26/2008) http://www.fueleconomy.gov/feg/driveHabits.shtml
  • Insurance Institute for Highway Safety. "Q&A: Airbags." (9/26/2008) http://www.iihs.org/research/qanda/airbags.html
  • Moore, Ron. "Knee Airbag Supplemental Restraint Systems." (9/24/2008) http://cms.firehouse.com/content/article/printer.jsp?id=32423
  • Safercar.gov. "Air Bags Safety." (9/25/2008) http://www.safercar.gov/portal/site/safercar/menuitem.13dd5c887c7e1358fefe0a2f35a67789/?vgnextoid=a93be66aeee35110VgnVCM1000002fd17898RCRD