Buick 2004 Century Owner's Manual page 59

If your vehicle has one, the driver's side impact air
bag is in the side of the driver's seatback closest to
the door.
CAUTION:
{
If something is between an occupant and an
air bag, the bag might not inflate properly or it
might force the object into that person causing
severe injury or even death. The path of an
inflating air bag must be kept clear. Don't put
anything between an occupant and an air bag,
and don't attach or put anything on the
steering wheel hub or on or near any other air
bag covering. Don't let seat covers block the
inflation path of a side impact air bag.
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