Year-long continuous radon monitoring was carried out (using Sarad Radon Scout devices) in a dwelling with high radon levels in the karst region of Slovenia. Two living rooms were selected: one on the ground floor with normal housework activities; and the second, on the first floor, closed and unattended. Meteorological data were also recorded. The following seasonal geometric means of radon activity concentration (kBq m⁻³) have been found: 6.28 ×/: 3.05 for spring, 1.25 ×/: 3.78 for summer, 5.17 ×/: 2.03 kBq m⁻³ for autumn and 9.83 ×/: 1.48 for winter on the ground floor; and...