A low pressure monitor for hybrid air bag systems for vehicles includes a pressure responsive disc 34.6 exposed on one side to a reference pressure chamber 34.11 and on the other side to the pressure in an air bag bottle 40 and positioned adjacent a movable arm 28.10 of an electric switch. The switch includes an electrically conductive sheet having a first portion partially encased in a base 26 of electrically insulative material and being connected to a first terminal 14 and a second portion forming the movable contact arm 28.10 extending from the insulative material and culminating with a portion formed with contact rib 28.14 adapted to be received beneath a laterally extending stationary contact portion 22 of a second terminal 16. Tabs 28.4, 28.6 extend from the sheet out of the insulative material for connection to a resistor 30 mounted on the electrically insulative base and a frangible portion 28.7 of the first portion is severed to place the resistor in series with the electrical contacts. The monitor is disposed in an air bag bottle with the disc 34.6 adapted to snap from one dished configuration to an opposite dished configuration whenever the pressure on the bottle decreases to a selected level. The movement of the snapping of the disc is transferred to the movable arm 28.10 separating the contact rib 28.14 from the stationary contact portion 22 opening the circuit.