210Pb in indoor air by total alpha measurement.

210Pb has been measured in indoor air by two methods. Low flow rate pumps and membrane filters were used to collect the samples. The air filter samples were stored for 1.7 y, after which total alpha activity was determined by scintillation counting. 210Pb was then chemically separated and measured by alpha spectrometry. The efficacy of determination of 210Pb by total alpha measurement was empirically proven. The average air concentration determined by total alpha counting was 340 microBq 210Pb m-3 and 360 microBq 210Pb m-3 by radiochemical analysis.