Understanding Airbags

Airbags are something we take for granted in cars, but this safety feature has only been federally-required for a bit more than a decade. When an airbag deploys, it cushions the occupant and reduces the impact of colliding with the steering wheel or other area of the car's interior, particularly if the person is not wearing his seat belt. But beyond basic operation, there are many different types and designs of airbags in vehicles that are currently on the road today. Let's look at the different types and what protection they offer.

Front Airbags
Front airbags are the only type of airbags that are a required safety feature. The National Highway Traffic Safety Administration (NHTSA) first required them in 1996, though driver-side front airbags were found in some cars earlier. First generation airbags deployed with extreme force, which was discovered could harm and even kill a child or a very small adult. As a result, NHTSA changed the airbag requirements in 1997 to allow a "depowered" airbag, which reduced the force it deployed while still providing extra protection beyond the seatbelt in a crash.

Most vehicles on the road today have advanced front airbags, which began being phased in with 2003 models and were required equipment for all 2006 models and newer. Automakers refer to advanced airbags by different names including "advanced," "smart," "dual-stage" and "multi-stage."

Advanced airbags deploy with less force and sometimes not at all in certain situations, such as for a very small occupant or for someone who is not sitting upright. To accomplish this, advanced airbags use sensors, typically located in the seats and seatbelts, which signal to the car's computer the weight, seating position and seatbelt use of the occupant, so the computer can make a split-second decision on whether to deploy at full-force, reduced force or not at all.

NHTSA requires these airbags to be safe for an average-sized man and a small woman wearing a seatbelt in a 30 mph crash. In addition, it requires the airbags to also not injure a small woman who is not using a seatbelt in a 25 mph collision.

While the small-woman crash test dummy is considered the equivalent of a 12 year old in size and weight (5 feet tall, 100 pounds), it is still not recommended any child under age 13 ride in the front seat. Medical studies indicate that until a child reaches puberty, there is a lack of bone density and muscle mass that puts the child at a greater risk of injury from an airbag, regardless of his or her height or weight.

Side Airbags
Of all collisions, side-impact collisions pose the greatest risk of injury to occupants because the "crush zone"--the space between a car's outer edge and its passenger compartment--is much smaller on the side than it is in the front or the rear. To better protect occupants, automakers developed side airbags to reduce injury to the head and torso. Since there are no federal requirements for side airbags, automakers have complete freedom in deciding whether or not to offer them. If they are offered, it's up to them to determine the design, location, size and whether they will be standard or optional.

Side airbags that protect the head only are commonly called head curtain airbags, though they may actually have a curtain or a tubular design. Both designs deploy from the roof downward, typically covering a large portion of the window area, and sometimes covering all of the window glass. They provide protection in a side impact crash to occupants seated in outboard positions adjacent to where the airbag deploys. Some head curtain airbags offer rollover protection, where the airbag stays inflated for an extended period if the vehicle's sensors indicate the possibility of a rollover. This gives occupants an added cushion of protection during a longer crash and also can prevent them from being ejected from the car should a window break.

This airbag design may not protect kids, however. "Most children sit too low to receive any protection from a head curtain type airbag," said Joe Nolan, vice president at the Insurance Institute for Highway Safety (IIHS). To see whether your child would be protected, it's best to look at the photograph in a vehicle brochure or automaker's website illustrating how far down the head curtain airbag deploys in your vehicle in relation to where your child's head is in the vehicle, including a young child seated in a child safety seat or booster seat.

Side airbags that protect the torso are often offered only for front-seat occupants, though a handful of automakers offer them in rear seats. These types of airbags usually deploy from the seat or the doors and offer a cushion that helps protect the rib cage and internal organs from injury. A vehicle that does offer rear seat side airbags may provide some protection to a child because a child's head may be in about the same location as the torso airbag when it deploys, but it is very unlikely it would cause any harm. While there are no federal safety requirements for these airbags, all major automakers perform a series of tests that confirm its side airbags will not injure a child or a small woman. Three dummies, representing the average 3-year-old, six-year-old and small woman, are used in the tests. Tests are conducted with the dummies sitting correctly and in a variety of other positions, including leaning on the door and window and lying down with the dummies head on the door's armrest to confirm that the side airbags will not cause injury if they deploy in a collision.

By Tara Baukus Mello