Abstract: A method and apparatus for temporarily incapacitating a malfeasant and others located in a relatively confined space of relatively known volume comprising, holding an incapacitant substance, moving the incapacitant substance from a tank by a pump to a vaporizer for vaporization of the incapacitant substance, mixing the vaporized incapacitant substance with a gas such as air in a relatively confined space of relatively known volume, monitoring the concentration of the incapacitant substance and gas mixture and controlling the rate of vaporization in response to the monitored concentration to reach a concentration sufficient for a given incapacitant substance to incapacitate a malfeasant and others located in the relatively confined space of a relatively known volume, and sensors for sensing and giving read out of the concentration of the incapacitant substance over a time period sufficient to incapacitate a malfeasant and others located in the relatively confined space of know volume.