Why Takata air bags explode

Nearly 34 million U.S. cars equipped with Takata air bags could be recalled after the Japanese manufacturer said the number of defective air bags was higher than previous estimates.

The air bags are blamed for six deaths and more than 100 injuries.

The air bag and its inflator are packed inside the steering wheel.

In an accident, a signal to the inflator triggers the air bag.

Takata's air bags use ammonium nitrate as a propellant to create gas for bag inflation. After prolonged exposure to high humidity and changes in temperature, the chemical can unexpectedly cause an explosion that sprays occupants with shrapnel if the bags deploy when the car is involved in a crash.