Free fractions, attachment rates, and plate-out rates of radon daughters in houses

The paper summarizes the experimental data on the equilibrium factor, F, the free fraction, f/sub rho/, the attachment rate to the room air aerosol, X-bar, the recoil factor, r/sub 1/, and the plateout rates of the free, q/sup f/, and the attached, q/sup a/, radon daughters, determined in eight rooms of different houses. In each room several measurements were carried out at different times, with different aerosol sources (cigarette smoke, stove heating, etc.) and under low (upsilon<0.3 h/sup -1/) and moderate (0.3<upsilon<1 h/sup -1/) ventilations. The mean value of the equilibrium factor F measured in houses without aerosol sources was 0.3 +- 0.1 and increased up to 0.5 by additional aerosol particles in the room air. The fraction of the free radon daughters had values between f/sub rho/ = 0.06-0.15 with a mean value near 0.1. Only additional aerosol sources led to a decrease of f/sub rho/ - values below 0.05. Besides the attachment rate the plateout rates had the greatest influence of F and f/sub rho/. The plateout rates of the free, q/sup f/, and the attached, q/sup a/, radon daughters obtained in rooms with low ventilation varied between 20 and 100 h/sup -1/ and 0.1 and 0.4 h/sup -1/ with average values of about 40 h/sup -1/ and 0.2 h/sup -1/, respectively. The recoil factor r/sub 1/ describing the desorption probability of Pb-214 atoms had a value of 0.50 +- 0.15, calculated from the measured data