As shown in Fig. 11, thecontaminant concentration decreased by 37% and 29% for spill location 1 (Cases 13 and 17) and 2 (Cases 14 and 18), respectively,
when changing the wall exhaust to the bench hood exhaust at 6
ACH. Comparing the reduction rate at 12 ACH where both the wall
exhaust and the bench hood exhaust were used in Fig. 9, using only
a bench hood exhaust was not as effective as using both a wall and
a bench hood exhaust