Abstract: A device for monitoring radon exposure including a cube-shaped, light-tight detection chamber having approximately one-inch square sides, five sides of which each contain an integrated circuit alpha particle detector, with a sixth side having fluid intake and exhaust ports and temperature and humidity sensors. Each integrated circuit device is responsive to detect alpha particles emitted by any decaying radon-222 atoms or daughter isotopes within the detection chamber. The detected results of each integrated circuit device is communicated to an external logic system which calculates the relative level of radon concentration within the chamber and stores the information in memory, or reports the information to a variety of peripheral devices.