Vehicle airbags work by inflating quickly to protect a passenger from severe injuries. They are designed to supplement the seat belts, but not to replace them. The main three parts of the vehicle airbag system are the bag, the sensor and the inflation system.
Airbags are located at the front of the dashboard, and some car brands have airbags on the sides as well. When a collision occurs, the sensors in front of the automobile quickly detect it, triggering the inflation of the bag. As of 2015, improved sensors can detect whether there is a person in the front passenger seat and whether the passenger's weight is enough for safe deployment of the bag. The sensor sends an electrical signal to a canister that contains sodium azide or another igniter compound. The heat from the detonation causes the igniter compound to decompose, producing a gas, such as nitrogen, that fills the airbag. The whole process takes approximately 30 milliseconds.
Also known as the supplementary restraint system, airbags are designed to inflate as soon as a car collision occurs and to deflate once the rider's head touches the bag. However, there is no guarantee that airbags can prevent injury or death.