A custom integrated circuit ("αRAM") capable of detecting the α particles emitted in the decay of radon and its progeny has been designed, fabricated and successfully tested. The αRAM has been incorporated in a complete radon monitor using electrostatic concentration of radon progeny. The monitor can detect hazardous levels of radon within hours.

A passive direct-reading radon monitor utilizing a custom α particle detecting MOS integrated circuit and electrostatic radon progeny concentrator has been designed, built and successfully tested. Radon concentrations at the threshold generally considered hazardous can be detected within hours. This monitor appears suitable for low-cost, high-volume production.