The Influence of Dust on the 210Po Signal in Retrospective Radon Measurements

Abstract

In retrospective radon measurements, the signal from implanted 210Po is to be correlated with the long-term radon concentration of the indoor environment. The magnitude of the surface activity of 210Po is affected by external factors such as plateout rate. In our evaluation of the retrospective method, using sheets of glass as samples, an obstacle for implantation of 210Po in glass might be the thin layer of dust covering every authentic sample. Dust is present in every 'normal' indoor aerosol environment and tends to cover openly exposed surfaces like pictures and photographs. Since the range of the recoiling nuclides from the alpha decay is short, approximately 50 nm, the dust particles may prevent radon daughters from implantation in the glass. In this study, 20 authentically dusty glass samples were exposed to high radon concentrations in a radon room facility. The 210Po signal was then evaluated and compared with a clean reference glass, exposed under the same circumstances. The aerosol conditions were kept at an appropriate level typical for the indoor dwelling environment. To quantify the area of the dust particles on the glass, extinction measurements were performed on the dust layer of the glass samples.