Abstract: A method for activating air bags in motor vehicles without the use of electrically powered deceleration sensors. This method utilizes the impact of one mass of quartz against another to generate a flash of visible light to initiate activation of the air bag system under conditions of extremely sudden deceleration. This flash of light, which is detected by a photo-sensitive element, initiates deployment of the air bag system without reliance on the electrical cables currently used for this purpose, but which could be damaged in the first moment of a collision, thus preventing inflation of the air bags. This substitution of a photo-sensitive activation system for a system dependent on electric cables substantially enhances the reliability of the air bag deployment concept.