Integrated measurements of 218Po, 214Pb and 214Bi + 214Po in air under environmental concentrations

A method determining time-integrated concentrations of each of the short-lived 222Rn progeny (218Po, 214Pb and 214Bi + 214Po) in air is proposed. It is based on the combination of an aerosol filter rotating with a period of 1 h and LR-115 type II solid state nuclear track detectors shielded with absorbers. The method is intended to work at integrated concentrations as low as 100 Bq h m−3 and to enable quantitative measurements in a mixed 222Rn and 220Rn atmosphere. If 220Rn progeny are present in measurable concentrations, their potential alpha energy concentration (PAEC) could be estimated as well. Experimental tests have been performed in the range of 222Rn progeny integrated concentrations of 20–5000 Bq h m−3 and for 218Po: 214Pb: 214Bi activity ratios ranging from a substantial disequilibrium (1:0.3:0.1) to about an equilibrium state. The experimental results presented suggest that the sensitivity of the method is sufficient for integrated measurements indoors and outdoors.