88 Short-term radon 222 measurement modelling

Introduction Radon concentration undergoes seasonal and daily changes. Those changes are kept into account by long-term measurement: in Italian law this period is one year. Following the excess of limits, it is mandatory to start mitigation activities. The assessment of the new concentration cannot exceed few weeks, otherwise it will infringe the want for workers’ safety. Methods The aim of present work is to assess feasibility of short-term measurement that can substitute longer ones. In order to do so we measured radon in the same room by two different methods one long-term integration (reliable) and another one that gives short-term time history. Radon concentration was assessed by half-yearly CR39 and active alfa spectrometer Tracerlab in the same room. The spectrometer daily curves were modelled by mathematical functions to fit changes while giving the CR39 integrated value. Result After comparison of modelled values with integrated ones, it comes out that the very important step is to keep into account, in the modellization, the occupation and the use of rooms, along with their duration. If this step is accurate, the numbers are comparable with those of passive methods. Discussion Essentially two occupational phases gives two functions to reproduce integrated values: a sinusoidal and an exponential function. The correct duration with the window opening/closing time profile, provide the estimation of values of parameters to be used with those functions. This gives the coincidence of actual and foreseen data of daily radon changes, saving a whole lot of measuring time and, hence, money.