Time changeability in radon concentration in one-family dwelling houses in the northeastern region of Poland.

Two groups of buildings (29 in total) were examined to assess the time changeability in radon concentrations. All the buildings showed seasonal changes with the individual schemes of radon concentration changeability, which varied together with the changes in outside weather parameters, such as temperature and pressure. Measurements based on several days exposure give values ranging from 0.1 to 3.4 of the annual mean. Monthly measurements of radon concentration presented values from 0.3 to 1.8 of the annual mean. A major part of the examined houses showed negative correlation between the indoor radon concentrations and the outside temperatures, and positive correlation between the radon concentrations and the changes in the atmospheric pressure.