Airbags
...sed laws requiring their use. There also have been efforts at employing technological fixes. The most unsuccessful one was tried in the United States in the early 1970s: an ignition interlock system that required that belts be fastened before the car could be started. Massive protests caused its repeal by Congress in 1976. Focus then shifted to passive restraints, devices that functioned automatically. Most of these were harnesses that automatically closed around a driver and passenger after the vehicle's door was shut. They were never popular. An alternative was the airbag, a device that protects a car's occupants by inflating in the event of the crash. These were first installed in some cars built by General Motors. Between 1973 and 1976, GM equipped 10,000 Buicks, Oldsmobiles, and Cadillacs with airbags at prices that ranged from $181 when installed in a 1974 Buick to $300 for a 1976 Cadillac. Demand did not live up to GM's expectations, falling far short of the 50,000 airbag-equipped cars that the company expected to sell during this period. Meanwhile, airbags had become a political issue as presidential administrations and federal courts went back and forth over the issue of mandating passive restraints. In 1984 the government stipulated that by 1990 all new cars sold in the United States had to be equipped with a passive-restraint system. By this time many automobile manufacturers were selling airbag-equipped cars to an increasingly safety-conscious car-buying public. Although airbags had met with considerable skepticism when they were first offered, they took on a new attractiveness when they were compared with other passive restraint systems. Airbags are inflated by the ignition of sodium azide (NaN3), a propellant that was originally developed by the Thiokol Corporation, a firm with wide experience in the development of solid-fuel rocket motors. When triggered by sensors that indicate a crash, the sodium azide produces a quantity of nitrogen gas that inflates the airbag in 40 milliseconds. The airbag then begins to deflate after another 40 milliseconds. An airbag diminishes or prevents injuries to a driver or passenger when a car is involved in a frontal or front-angle impact, but these comprise a minority of collisions. Airbags are of less value in cases of rollovers, rear-enders, or side impacts (however, a few cars are now being equipped with side-impact airbags). According to a study by the National Highway Traffic Safety Administration, airbags have reduced the fatality rate in car accidents by 11 percent. However, it is important to note that airbags offer less protection than seatbelts, and they should not be viewed as substitutes for the latter. For seatbelt wearers, the addition of an airbag results in a small but useful improvement in safety. Seatbelt use lowers the fatality rate by 45 percent, while the use of airbags in conjunction with seatbelts lowers the fatality rate by 50 percent. Although airbags increase automotive safety, their manufacture entails considerable danger. In 1994, one worker was killed and several others injured when sodium azide was accidentally ignited at a factory making airbags in Arizona. Sodium azide is also a toxic material; exposure to its vapors, fumes, or dust can cause irritation and burning of the skin, eyes, mucous membranes, and respiratory and gastrointestinal tracts. Consequentl...