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About Air Bags
Air bags, an automatic crash protection system that deploys quicker than
the blink of an eye, are the result of extensive research to provide
maximum crash protection. Air bags by themselves protect only in frontal
crashes, and offer maximum protection when used in conjunction with
safety belts. Air bags should NOT be used as the only form of occupant
protection; they are intended to provide supplemental protection for
belted front-seat occupants in frontal crashes.
Typical air bag systems consist of three components: an air bag module,
crash sensor(s), and a diagnostic unit. The air bag module, containing
an inflator and a vented or porous, lightweight fabric air bag, is
located in the hub of the steering wheel on the driver side or in the
instrument panel on the passenger side. Crash sensor(s), located on the
front of the vehicle or in the passenger compartment, measure
deceleration, the rate at which a vehicle slows down. When these
sensor(s) detect decelerations indicative of a crash severity that
exposes the occupants to a high risk of injury, they send an electronic
signal to the inflator to trigger or deploy the bag. The diagnostic unit
is an electronic device that monitors the operational readiness of the
air bag system whenever the vehicle ignition is turned on and while the
ignition is powered. The unit uses a warning light to alert the driver
if the air bag system needs service.
Air bags are designed to deploy (inflate) in moderate-to-severe frontal
and near-frontal crashes. They inflate when the crash forces are about
equivalent to striking a brick wall head-on at 10-15 miles per hour or a
similar sized vehicle head-on at 20-30 mph. Air bags are not designed to
deploy in side, rear, or rollover crashes. Rollover crashes can be
particularly injurious to vehicle occupants because of the unpredictable
motion of the vehicle. In a rollover crash, unbelted occupants can be
thrown against the interior of the vehicle and strike hard surfaces such
as steering wheels, windows and other interior components. They also
have a great risk of being ejected, which usually results in very
serious injuries. Ejected occupants also can be struck by their own or
other vehicles. Since air bags provide supplemental protection only in
frontal crashes, safety belts should always be used to provide maximum
protection in rollovers and all crashes.
The bag inflates within about 1/20 of a second after impact. The
inflated air bag creates a protective cushion between the occupant and
the vehicle's interior (i.e., steering wheel, dashboard, and
windshield). At 4/20 of a second following impact, the air bag begins to
deflate. The entire deployment, inflation, and deflation cycle is over
in less than one second.
After deployment, the air bag deflates rapidly as the gas escapes
through vent holes or through the porous air bag fabric. Initial
deflation enhances the cushioning effect of the air bag by maintaining
approximately the same internal pressure as the occupant strokes into
the bag. Subsequent rapid and total deflation enables the driver to
maintain control if the vehicle is still moving after the crash and
ensures that the driver and/or the right-front passenger are not trapped
by the inflated air bag.
Dust-like particles present during the inflation cycle primarily come
from dry powder that is often used to lubricate the tightly packed air
bag to ease rapid unfolding during deployment. Small amounts of
particulate produced from combustion within the inflator also are
released as gas is vented from the air bag. These dust particles may
produce minor throat and/or eye irritation. Once an air bag is deployed,
it cannot be reused. Air bag system parts must be replaced by an
authorized service dealer for the system to once again be operational.
To ensure that infants and children ride safely, with or without a
passenger-side air bag, NHTSA urges care givers to follow three "rules":
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Make sure all infants and children are properly restrained in child
safety seats or lap and shoulder belts for every trip.
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The back seat is the safest place for children of any age.
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Infants riding in rear-facing child safety seats should never be
placed in the front seat of a vehicle with a passenger-side air bag.
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Effectiveness of Airbags and other
Vehicle Restraint Systems |
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| System Used |
All
Damage Areas |
Front
Damage |
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| Air bag plus lap-shoulder belt
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59% |
69% |
| Air bag alone |
7% |
- 8% |
| Automatic (2-point and 3-point)
belt |
37% |
33% |
| Manual lap-shoulder belt |
60% |
74% |
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Estimated Effectiveness of
Occupant Protection Systems
in Reducing the Likelihood of Serious and Greater Injury
(MAIS 3+)
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