Abstract
Results of study on the concentration of uranium and the activity ratio of 234U/238U in surface air in Tokyo and Tsukuba Science City indicate that the average concentrations of uranium are 24±15 pg m-3 and 14±10 pg m-3 respectively, and the average activity ratio is about 1.0. The high ratio up to 1.7 observed in three spring seasons. The causes of these high isotopic ratios of 234U/238U may be due to the effect of ablated debris deriving from the atmospheric burn-up of Cosmos-954 on 24 Jan. 1978 over northern Canada.
