176 DREVINSKY AND PECCI 30 TT TTT TTT rT TTT ALTITUDE, KM 25 |= TTT TTT \ 4 20 F = bE 4 Mar. 16, 1962 10 5 0 107! 30 < A >0.15 p RADIUS X 0.02 TO 0.15 p RADIUS @ <0.02 p RADIUS Ly f py yyy] 10° «T1117 Ly} aan _ puyyyyl 10! Mice/MSe ACTIVITY RATIO TTT T1177] X———p 25 | , | jf gygyy 10° [TTT TTT __| -——X—+4 _ ALTITUDE, KM 20 t15 10 F- — Sept. 25, 1962 A >0.15 p RADIUS X 0.02 TO 0.15 p RADIUS @ <0.02 p RADIUS = — _ 5 0 107! tt ttyl 10° Lt LE pail 10! Mice/%Sr ACTIVITY RATIO Lot ot et 10° Fig. 6—'!#Ce/*Sy activity ratios for impactor—filter collections over Minneapolis, Minn. (45°N 93°W), on Mar. 16 and Sept. 25, 1962.