I viewed a cut-open inflator device and saw where the explosion actually took place. I'm told that the nylon bags themselves are dusted with corn starch or talcum powder during the packing process to ensure smooth inflation. In addition, the deployed airbags I inspected have large venting holes from which the explosion gases immediately escape. The escaping gases contain small amounts of smoke from the explosion, as well as sodium hydroxide, a powdery byproduct of the chemical reaction. So people who report smoke are partially correct.
Some cars have as many as five sensors.
At least two have to agree that a crash is occurring before the bags inflate. This ensures that one sensor can't go haywire and explode the airbags all by itself. Airbags are a highly engineered part of your car. In addition to visiting Keith Schieffer, I talked with Tracy Tellman, traffic safety specialist with the Texas Department of Transportation. Airbags are the most important safety device in a car.