Since the onset of our surface air analyses for Pu-239, in late 1965 through the beginning of 1968, rarely did any sample from the Northern Hemisphere indicate a ratio in excess of 2.5%, and the few that did were always analytically suspect. This relative constancy of the ratio had been noted by other investigators in earlier studies of stratospheric samples (1). In the Southern Hemisphere, high ratios in surface air were seen closely following the small French Tests in 1966 and 1967. The peak ratios appear to be displaced poleward relative tc the reported latitude of the Southern Hemisphere tests. Recognizing that some debris from these tests did enter the lower stratosphere and that these peaks prevailed throughout the spring of each year, we feel that the geographical and temporal extent of the highs are not unexpected. As a result of the 6th Chinese test (June 1967) most of which was deposited in the stratosphere, the gradual rise in the Pu-239/Sr-90 in the Northern Hemisphere surface air from less than 2% in mid-1967 to almost 3% by mid 1968 was not surprising. Starting with June 1968, however, and persisting well into 1969, numerous samples were measured with ratios over 3% and a few even exceeded 4%. From Figures 1 and 2 it seems clear that ratios such as these could not be derived from the debris in the stratosphere without some fractionation of these two nu= clides between the tropopause and the earth's surface. spe I - 1?