Radon concentration in basements of old buildings in the oldest towns of Lu
blin region (Zamosc, Chelm and Sandomierz) was determined. Two techniques w
ere applied: passive Pico-rad) and alpha-spectrometry for radon progeny con
centration measurement (SILENA. It was found that only 7% of results exceed
ed a dose limit of 400 Bq.m(-3), established for old buildings. Radon conce
ntration levels ranged from 0.2 to 5150 Bq.m(-3) Distribution of the result
s satisfied a log-normal relationship. Applying these two methods at the sa
me time, the radioactive equilibrium factor of radon and its progeny was de
termined. In the underground ways, open for visitors, no higher radon conce
ntration was observed.