Ogoya underground laboratory for the measurement of extremely low levels of environmental radioactivity: review of recent projects carried out at OUL

Recent topical measurements performed in the Ogoya Underground Laboratory are briefly summarized. The paper deals mainly with the following topics: measurements of variations of airborne 222Rn, 210Pb, 210Po and 7Be with high temporal resolution; the depth profile of 137Cs in Pacific water collected in 1957; cosmic-ray-induced 22Na in surface air, rain, river and lake waters; 152Eu in granite exposed to the Atomic Bomb in Hiroshima in 1945; and depleted uranium used in the Iraq War 2003.