30 TT TTT l TT 177 TTTTT 25 _ 20 -- — 2 15; ~ s — T T _l Af -_ = —_/ £10 d > 0.15 p RADIUS 5 0 10! 30 val 4 X 0.02 TO 0.15 p RADIUS ® < 0.02 p RADIUS po 107 fo = tt M4ce/%S- ACTIVITY RATIO ! 10° TT rt ry ae ! a ALTITUDE, KM _| 10 aa 5/L _ 0 10° 30 \ L tyre r TT l 10! 57 -/9S- ACTIVITY RATIO TTToty Lot put 107 TTT TTTT Lao = 20 f— = Mw ut S15 }he am _ | 4 10 4 4 3 f— 0 1077 l a ft 10° 957-/\4Ce ACTIVITY RATIO | [yyy 10! Fig. 7—Activity ratios for impactor—filter collections over Minneapolis, Minn. (45°N 93°W), on May 16, 1963.