The gamma-ray spectroscopy method was used to determine the natural activity of soil samples taken from twenty-six locations including three nuclear reactor sites in order to obtain the average background activity of Taiwan. Direct measurement of natural activity was also carried out by means of ionization chambers coupled with a vibrating reed electrometer. Fallout activity was detected during this investigation by spectroscopy method, and chemical method was used to analyze its main components 90Sr and 137Cs nuclides. The background radiation thus measured varied from 5.2μR/h to 15.2μR/h with an average value of 11.8μR/h while the gross activity concentration in air varied from 1.94×10-13μCi/cm3 to 4.95×10-13μCi/cm3 with an average value of 3.58×10-13μCi/cm3.
