INTERCOMPARISON OF METHODS FOR INVESTIGATING THE PHYSICAL CHARACTERISTICS OF RADON DECAY PRODUCTS IN THE INDOOR ENVIRONMENT

The average activity concentrations of radon gas and its short-lived decay products were measured under normal living conditions and deviated by less than 10% during an intercomparison between the three European groups of the National Radiological Protection Board (UK), Ghent (Belgium) and Gottingen (Germany). The spread in the derived unattached fraction, f(p), ranged up to 50% in situations without additional aerosol sources (average f(p)=0.1) and the variation in the evaluated attachment rate X and plateout rates q(a) and q(fl) was sometimes two-fold. Different size fractionating methodologies yield similar AMD/AMADs of 200 nm for the accumulation mode (deviation < 30%) during measurements in a low ventilated room with an aged aerosol. Active aerosol sources yield complex size distributions in the attached region and varied by a factor of 2.