Water originated from groundwater systems can have relatively high concentration of radon. In many situations, radon is released
from the water and mixes with the indoor air. In the present study, laboratory experiments were conducted to characterize
the airborne radon released by showering and the use of a washing machine. The followings were discussed: (1) a comparison
between the loss of waterborne radon and the increase of airborne radon, (2) time-related changes in airborne radon after
the water use, (3) changes in the equilibrium factor, and (4) the relationship between radon concentration and the distance
from the source of radon release.