Alpha Air Monitor Alarm Sensitivity: Operational Experience

The United States Department of Energy conducted a review of alpha air monitor alarm sensitivity at a number of its facilities. Alarm performance sensitivity was determined by comparing instrument alarm occurrences to data from retrospective (passive) air sampling. Active monitoring units were found to alarm in only 15-30% of those occasions when elevated room air levels were observed, even at levels of several hundred DAC.h. The study's findings suggest that the location of active monitoring units relative to the release point is a critical factor in instrument response. False alarm rates (i.e. alarms occurring in the absence of elevated air levels) were also reviewed and were found to be as high as 95% for some of the facilities surveyed. Though there were few actual uptakes, these results raise questions concerning generally accepted practices for worker protection and the value of active monitoring units.