Atmospheric radioactivity has been increasingly detected in recent years, raising concerns about the sources and possible health consequences, such as the Ru-106 detection in Europe in 2017 and Cs detection during 2020 Chernobyl fire. However, the release of atmospheric radioactivity can only be inversely estimated using remote environmental observations, leading to large uncertainties in the estimates. Here, we investigate the source and propagation of these uncertainties, and propose improved inverse modeling methods and atmospheric transport model to reduce such uncertainties. The proposed models identify the source of atmospheric radioactivity with higher accuracy and provides more details about atmospheric transport of radioactivity.