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

222Rn 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 × 10-3 Bq m-2 s-1. The average natural flow rate in the spring–summer is about 0.70 m3 s-1 and the autumn–winter is approximately 3.6 m3 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