Kia Optima 2004 Owner's Manual page 61

The air bags will completely inflate
and deflate in less than 1/10 of one
second.
The speed of inflation and deflation
protects the driver's ability to operate the
vehicle. This is important in crashes
where a vehicle continues to move after
an impact and the driver still has some
control of the vehicle's steering, braking,
throttle and/or transmission systems.
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KNOWING YOUR VEHICLE
It is virtually impossible for you to see
the air bags inflate during an accident.
It is much more likely that you will
simply see the deflated air bags hanging
out of their storage compartments after
the collision.
In order to help provide protection in a
severe collision, the air bags must inflate
rapidly. However, that speed also causes
the air bags to expand with a great deal
of force. The speed of this inflation has
been determined by the law to reduce the
likelihood of serious or life-threatening
injuries and is thus a mandatory part of
air bag design.
Steering wheel
air bag
AS2B03033
Thus, air bag inflation could also cause
injuries which normally can include
facial abrasions, bruises and broken
bones. However, there are even
circumstances under which contact
with the steering wheel air bag can
cause fatal injuries, especially if the
occupant is positioned excessively
close to the steering wheel.
You must always sit as far back from
the steering wheel air bag as possible,
while still maintaining a comfortable
seating position for good vehicle
control, in order to reduce the risk of
injury or death in a collision.