An Improved Method to Determine $210Pb,$ $210Bi$ and $210Po$ in air Aerosol Filters

$222Rn$ daughters (e.g. $210Pb,$ $210Po,$ $210Bi$⁠) have been widely used to study a variety of atmospheric processes. Many works in literature about $222Rn$ daughters do not specify the way by the activities of these radionuclides are calculated. Besides, $210Po$ corrections due to the in‐growth of $210Bi,$ if taken into account, are not indicated. In this work, the increase in uncertainties of radionuclides activities due to delay between air sampling and radionuclides determinations have been evaluated and the influence of neglecting the contribution of $210Bi$ in‐growth to $210Po$ determination has been estimated. The results indicate that, in general, ignoring the $210Bi$ in‐growth in $210Po$ determinations lead to significant differences (could reach until 100%) between the estimation of $210Po$ activity and its true value.