The airbag is a vehicle safety device. It is restraining device designed to inflate rapidly during an automobile collision. It prevents the driver and passenger from striking the steering wheel or a window. The airbag is designed to only inflate in moderate to severe frontal crashes. Airbags are normally designed with the intent of supplemental protection of those already restrained with a seatbelt. Most designs are inflated through pyrotechnic means and can only be operated once. The National Highway Traffic Safety Administration estimates that the combination of an air bag in addition to a lap and shoulder belt reduces the risk of serious head injury by about 80%, compared with 60% reduction for belts alone. The first commercial designs were introduced in passenger automobiles during the 1970s. Commercial adoption of airbags occurred in many markets during the late 1980s and early 1990s with a driver airbag, and a front passenger airbag as well on some cars; and many modern vehicles now include four or more units. Infants should NEVER ride in the front seat of a vehicle with a passenger air bag. Children ages 12 and under should always be properly restrained in a child safety seat or safety belt and ride in the back seat. Even if there isn't a passenger air bag in the motor vehicle, the safest place for infants and children is properly secured and buckled up in the back seat.