Effects of polonium-210 on determination of atmospheric gross alpha-radioactivity

Ingrowth and decay of²¹⁰Po on air filters used for gross alpha-determination can lead to errors in estimation of long-lived airborne radioactivity. Interferences are present to some degree in all samples and change with time, making the gross alpha-technique quantitatively invalid. However, since the degree of equilibrium between²¹⁰Po and its parent²¹⁰Pb can be calculated at any time after filter collection, it should be possible to use the gross alpha-method to estimate past atmospheric concentrations of²¹⁰Pb. Measurements on filters after elapsed times of up to 15 years show that such determinations are feasible.