Correlation of 210 Po implanted in glass with radon gas exposure: sensitivity analysis of critical parameters using a Monte-Carlo approach

In recent years, 210Po implanted in glass artefacts has been used as an indicator of the mean radon gasconcentration in dwellings in the past. Glass artefacts have been selected in many dwellings and the?-recoil implanted 210Po concentration has been measured using various techniques. Some of theseretrospective techniques use a model to estimate the retrospective radon gas on the basis of thissurface 210Po activity. The accumulation of 210Po on glass surfaces is determined by the depositionregime over the exposure period. The 210Po activity is determined not only by the radon progenydeposition velocities, but by other room parameters such as ventilation rate, aerosol conditions and thesurface to volume ratio of the room. Up to now in using room models, a nominal or base-casescenario is used, i.e. A single value is chosen for each input parameter. In this paper a Monte-Carloanalysis is presented in which a probability distribution for each parameter is chosen, based onmeasurements quoted in the literature. A 210Po surface activity is calculated using a single valuedrawn from each of the parameter distributions using a pseudo-random number generator. Thisprocess is repeated n times (up to 20000), producing n independent scenarios with corresponding 210Povalues. This process permits a sensitivity analysis to be carried out to see the effect of changes ininputs on the model output.