Outdoor Radon and Its Progeny in Relation to the Particulate Matter during Different Polluted Weather in Beijing

Abstract

This study aimed to investigate the differences in the relationship between radon and its progeny concentrations and particulate matter concentrations under varying pollution weather conditions. Outdoor radon and its progeny concentrations were measured by a radon/thoron- and radon/thoron progeny monitor (ERS-RDM-2S) during haze and dust storm weather in Beijing. Particulate matter concentrations and meteorological data were simultaneously recorded. Results showed that radon and its progeny concentrations exhibited a diurnal variation pattern, with a minimum in the late afternoon and a maximum in the early morning. The average radon concentrations were similar under both pollution weather conditions, but significantly higher than the reported average for Beijing. The equilibrium equivalent radon concentration during haze was about two times that during a dust storm. PM10 concentrations were similar in both pollution weather conditions, but PM2.5 concentrations during haze were approximately 2.6 times higher than that during dust storms. A positive correlation was observed between radon and its progeny concentrations and particulate matter concentrations, but the correlation was significantly higher during haze than during dust storms. The higher PM2.5 concentration during haze significantly increased the correlation between radon and its progeny concentrations and particulate matter concentrations. We recommended protecting against radon exposure during pollutant weather, especially haze.