When there is a moderate to severe crash, a signal is sent from the air bag system's electronic control unit to the inflator within the air bag module.
An igniter in the inflator starts a chemical reaction that produces a harmless gas, which inflates the air bag within the blink of an eye - or less than 1/20th of a second.
Side-impact air bags inflate even more quickly since there is less space between the occupant and the striking object, such as the interior of the vehicle, another vehicle, a tree, or a pole.
Because air bags deploy very rapidly, serious or sometimes fatal injuries can occur if the occupant is too close to - or is in direct contact with - the air bag when it first begins to deploy.
Sitting as far back from the steering wheel or dashboard as possible and using seat belts help prevent occupants from being "too close" to a deploying frontal air bag.
Up until recently, nontoxic cornstarch or talcum powder was commonly used to lubricate air bag fabrics and aid in deployment. While these lubricants may sometimes appear to be "smoke" when released during deployment, they are actually harmless substances.
Most of today's air bag fabrics and coatings (i.e., silicone) are sufficiently "slippery" that additional powder-like lubricants aren't necessary.
Exceptions include some heavily coated side curtain air bags developed for rollover crash protection; these air bags may still be lubricated with talcum powder, which could potentially appear as "smoke" when these air bags inflate.
