Dynamics of Aerosol Removal from the Atmosphere Based on Dose Rate Change

Abstract Atmospheric aerosols containing natural radionuclides, particularly short-lived progeny of radon, play an important role in environmental radiation levels and in the transport of airborne pollutants. Their atmospheric residence time and removal through wet and dry deposition strongly depend on meteorological conditions; however, these processes are often estimated using theoretical models or short-term experiments rather than long-term environmental observations. In this study, the dynamics of radioactive aerosol removal were investigated using empirical data derived from continuous gamma dose rate monitoring and meteorological measurements collected over a 10-yr period (2014–23) at two urban locations in central Poland (Lodz and Warsaw). Variations in ambient gamma dose rate associated with precipitation events were analyzed in relation to temperature, humidity, and rainfall using multiple regression analysis. Separate scavenging coefficients were determined for wet deposition (precipitation) and dry processes represented by temperature and humidity changes. The obtained scavenging coefficients remained within typical theoretical ranges, while aerosol residence times showed clear seasonal variability, ranging from 3 to 29 days. The proposed approach demonstrates that long-term gamma monitoring data can be used as a practical proxy for quantifying aerosol washout processes under real atmospheric conditions. This methodology can support environmental radiation monitoring, improve parameterization in atmospheric transport models, and assist in the rapid assessment of aerosol behavior during radiological incidents or air pollution events. Significance Statement Airborne particles (aerosols) can carry natural radioactive substances and other pollutants that influence environmental radiation levels and human exposure. Understanding how quickly these particles are removed from the atmosphere is important for air quality studies and for assessing radiological risks. In this study, we analyzed 10 years of gamma radiation monitoring data together with meteorological observations from two cities in central Poland. We found that rainfall is the dominant process removing radioactive aerosols from the atmosphere, while temperature and humidity have smaller effects. By examining radiation changes during precipitation events, we developed an empirical method to estimate how long aerosols remain suspended in the air. The results show strong seasonal variability, with residence times ranging from a few days in summer to several weeks in winter.