“In the process of urbanization, new progress has been made in the study of changes in atmospheric radioactivity levels in Beijing. By measuring the radioactivity of tree rings, the trend of atmospheric radioactivity levels in Beijing was analyzed. Research has found that the concentration of 14C activity in tree rings in Fangshan District has been decreasing year by year, while the concentration of 210Pb activity first increases and then decreases; There is no significant variation in the activity concentration of 210Pb in tree rings near the west gate of Tsinghua University. The study provides an important reference for understanding the impact of urbanization on atmospheric radioactivity levels.”