20, 10 (> 1.5, <1.75 £3 > 1.75, <2.00 > 2,00, <2.25 WB > 2.25, <2.50 EBM > 2.50, <2.83 GROUND ZERO Figure 15. Contours of the Factor 10°OK for Obtaining an Approximate 95 Percent Confidence Interval for the Average Geometric Mean Concentration 10P(v). 397