In situ soil 222Rn and 220Rn and their relationship with meteorological parameters in tropical Northern Peninsular Malaysia

This study focused on the relationship between soil 222Rn and 220Rn concentrations and meteorological parameters (temperature, pressure, humidity, and terrestrial gamma radiation) in Northern Peninsular Malaysia. Measurements of in situ soil 222Rn and 220Rn concentrations were performed in surface air and at a sampling depth of 50 cm using two active techniques: RAD7 radon detector and radon continuous monitor (Sun Nuclear Corporation). The surface air 222Rn concentration ranged from 6 Bq m−3 to 79 Bq m−3, whereas at the depth of 50 cm, the 222Rn and 220Rn concentrations varied from 133 Bq m−3 to 143,059 Bq m−3 and from 55 Bq m−3 to 403 Bq m−3, respectively. The gamma dose rate (DR) in air was measured using a GR-135 spectrometer (Exploranium). The dose rate varied from 80 nGy h−1 to 258 nGy h−1. The 222Rn concentration in the soil (143 kBq m−3) was high considering that the concentration in typical soil samples is only 40 kBq m−3. The 222Rn concentration in surface air varied within the recommended activity values prescribed by the United States Environmental Protection Agency and the International Commission on Radiological Protection. Weak positive and negative correlations were observed between the (222Rn and 220Rn) concentrations and the meteorological parameters.