Two-filter monitor for atmospheric 222Rn.

A two-filter, continuous monitor has been developed for atmospheric (222)Rn. Features include a sensitivity of better than 0.01 pCi/l, a high specificity for (222)Rn, and immediate start up capability. The monitor has been computer modeled to facilitate calibration and selection of operating parameters. The filters are stationary and require no moving parts for control. Field trials indicate high reliability and maintenance-free operation for periods of a week and longer.