222Rn concentrations, natural flow rate and the radiation exposure levels in the Nerja Cave

Rn-222 concentrations in the air in Nerja Cave (Spain) have been measured over 4 yr and at four sampling points. Concentrations average 168 Bq m(-3) in the spring-summer when the temperature lapse rate provides a stable cave atmosphere. In the autumn-winter, the radon levels decrease to 48 Bq m(-3) 222Rn flux has also been measured for soils in the cave, with an average value of 34 x 10(-3) Bq m(-2)s(-1). The average natural flow rate in the spring-summer is about 0.70 m(3)s(-1) and the autumn-winter is approximately 3.6 m(3)s(-1) determined over 1992-1995. The radiation exposure levels for workers and tourists represent only a low percentage of the exposure guides for the general population. (C) 1998 Elsevier Science Ltd. All rights reserved.