Behaviour of radon, radon progenies and particle levels during room depressurisation

The aim of the study was to investigate the effect of room depressurisation (up to - 28 Pa) on indoor radon, radon progenies and particle concentratio ns in a wooden school building (A) and in a wooden double-family house (B). The airborne concentrations of particles, radon, and radon progenies decre ased with increased depressurisation. At the same time, the air exchange ra tes increased by a factor of 9.5 (house A) and 13 (house B). The calculated radon entry rates thus rose almost in the same ratio, 6.3 and 12, respecti vely. The equilibrium factors between radon progenies and radon were the sa me before and after the depressurisation being 0.04 in house A and 0.16 in house B. When the pressure was the lowest, radon concentrations decreased b y a factor of 0.7 in house A and 0.9 in house B, and the radon progeny leve ls fell by a factor of 0.6 in both houses. The particle levels (particles e xceeding 0.01 mu m) decreased by a factor of 10 (house A) and of 1.2 (house B). The dilution by outdoor air was more effective in house A, which was l ess tight. (C) 2000 Elsevier Science Ltd. All rights reserved.