Activity size distribution of radon progeny in indoor air: comparison of model to data

The activity size distributions of radon progeny in indoor air are considered. A general theoretical model is presented and then applied to this experiment where experimental data was obtained in a very large and nearly airtight laboratory for two cases: low particle concentration (Case 1) and high particle concentration (Case 2). The balance equations of aerosol particles, radon, and radon progeny in indoor air are solved numerically. The effects of particle coagulation are noticeable for u = 0.005 ms-1, (u. equals friction velocity) but negligible for u = 0.015 ms-1 as long as we adopt a certain theoretical model of wall deposition. Numerical results agreed rather well with this experimental data. Furthermore, an example calculation was done in the case of a usual living space with a high air-exchange rate.