<p>In recent years, the study of atmospheric particulate matter has provided valuable insights into the behavior and transport of aerosols and associated radionuclides. This study investigates the seasonal and monthly variations of total particulate matter (PM) and the cosmogenic radionuclide ⁷Be in the atmosphere of Tehran, Iran, over a one-year period. Particulate samples were collected using a high-volume air sampler (1.5 m³/min) on fiberglass filters for six-hour intervals at a height of 8&#xa0;m. The filters were weighed to determine total PM concentration and subsequently analyzed for ⁷Be activity. Meteorological parameters including temperature, relative humidity, wind speed, and precipitation were also measured to assess their effects on PM and ⁷Be levels. Results showed that PM concentration increased markedly during the warm and dry months due to frequent dust storms and strong winds, while lower values occurred in the cold and wet seasons. The annual mean ⁷Be activity was 4.41 ± 0.87 mBq.m^− 3, with the highest concentrations recorded in summer and early autumn and the lowest in winter. Pearson correlation analysis revealed a strong negative association between ⁷Be concentration and relative humidity (<i>r</i>=-0.759), highlighting the dominant role of wet scavenging processes. An increase in wind speed intensified the horizontal transport of suspended particles in the atmosphere near the Earth’s surface, while solar radiation and atmospheric stability strongly influenced its seasonal distribution. Overall, the combined analysis of meteorological and radiological data highlights the complex interactions controlling aerosol dynamics and radionuclide behavior in Tehran’s urban atmosphere. The results of the RPCI interpretation indicate that the variability of 7Be is primarily controlled by atmospheric humidity and mixing dynamics rather than just the concentration of suspended particles.</p>