DYNAMIC-MODEL FOR ASSESSING RN-222 AND PROGENY EXPOSURE FROM SHOWERING WITH RADON-BEARING WATER

In homes supplied by water with a high radon content, inhalation expos ure from the radon in the water may occur on two different time scales : (a) long-term exposure that occurs due to an increase in the backgro und radon concentration from radon released during water use and (b) s hort-term exposure that occurs during actual radon use such as in the bath, kitchen, and laundry room. While the former mode has been the su bject of several studies, not much is known about the latter mode of e xposure. During water use,the radon concentration can be considerably higher than the background and varies rapidly with time. Most of the e xposure occurs well before a steady state can be reached. The goal of this work was to develop a dynamic, size-dependent model for the radon progeny activity during showering. The model includes radon and proge ny decay, attachment of progeny to the existing aerosol, recoil, venti lation, and surface deposition. The model is used to evaluate radon ex posure during and subsequent to showering as a function of environment al and other parameters (such as aerosol profile, bathroom dimensions, ventilation rate, and shower duration). These results are used in con junction with a recent dosimetric model to obtain the integrated lung dose as a function of time.