Health Phys

Objective:The primary objective of this work was to characterize employee exposure to radon and progeny while performing guide/interpretation and concessions duties in a tourist cavern.Methods:Radon gas and progeny concentrations, fraction of unattached progeny, and other environmental parameters were evaluated in a popular tourist cavern in Southeastern New Mexico. Alpha-track detectors were used to measure radon gas in several cavern locations during a nine-month period. Additionally, radon gas and attached and unattached fractions of radon progeny were measured at three primary cavern work locations during a one-day period using a SARAD EQF 3220.Results:Radon gas concentrations in the cavern were elevated due to extremely low air exchange rates, with substantial seasonal variation. Mean measured radon concentrations ranged from 970 to 2600 Bq m 123 in the main cavern and from 5400 to 6000 Bq m 123 in a smaller cave associated with the regional cave system. Measurements of unattached fractions (0.40\u20130.60) were higher than those commonly found in mines and other workplaces, leading to the potential for relatively high worker dose.Conclusions:Although radon gas concentrations were below the Occupational Safety and Health Administration Permissible Exposure Limit, employees working in the cavern have the potential to accrue ionizing radiation dose in excess of the annual effective dose limit recommended by the National Council on Radiation Protection and Measurements due to high unattached fraction of radon progeny. There was a strong negative correlation between unattached fractions and equilibrium factors, but these parameters should be further evaluated for seasonal variation. Introduction of engineering controls such as ventilation could damage the cavern environment, so administrative controls, such as time management, are preferred to reduce employee dose.CC999999/ImCDC/Intramural CDC HHSUnited States/2022-06-01T00:00:00Z33470714PMC865034011425vault:4051