APPENDIX UNCLASSIFIED 5 ESTIMATE OF COLLECTION EFFICIENCY OF FILTERS USED IN JET A rilter papers were placed in series during two flights. If we as titers do not significantly discriminate according to particle siz afficiency can be estimated as follows. Let 8 2 fraction of activity retained on filter CG = Activity in volume of air sampled A, and A, = Activity collected by first and second filters respectively Then 4, = EC Ay = (1-k) 0 Rzle- é The following data were obtained: November 30, 1953 First filter in series Secon filter in series S 780 d/sin 60 d/sin Bra Si x 2 .92 as December 15, 1953 a Firet filter in series #. Second filter in series ns 2070 d/min 140 d/min R=1- 10 2070 HT | | = 9 00131986.06! [051090 ff