To investigate the influence of aerosol concentration on the indication of radon progeny concentration in air, measurements with a mining radiometer RGR-30 were carried out in a radon chamber. The aerosol and radon concentrations in the radon chamber were controlled and the radon progeny concentration was measured by the RGR monitor. Additionally, the count rate originating from alpha activity deposited on an air filter was measured in 1 min intervals that were later used for three interval data processing. It was found that for the aerosol concentration from 40 to approx. 12000 p/cm³ indications of the RGR monitor depends considerably on aerosol concentration. Radon daughters concentration normalized to radon concentration against aerosol concentration varied from 0.3 to 0.9. To establish whether the observed effect is due to the lower concentration of radon daughters inside the radon chamber (plate out of radon daughters) or due to the lower detection efficiency of the air filter in the RGR monitor and plate out in the RGR air duct, or both of them, additional measurements with a radioactive aerosol spectrometer inside the radon chamber should be carried out.
It was found that the Principal Component Regression (PCR) data processing ensures a lower random error than the three interval data processing. When employing the PCR data processing, the concentration of radon daughters Po-218, Pb-214 and Bi-214 is determined from PCR procedures, whereas potential alpha energy (PAE) should be computed from radon daughters concentration using known relations.