TABLE 2
FORMULA FOR CALCULATION OF THE 95 PERCENT CONFIDENCE LEVEL
(Reference: NIOSH 7400)
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Fibers/cc(01.95 percent CL) = X + [(X) * (1.645) * (CV)]
Where:
X = ((E)(AC))/((V)(1000))
E = ((F/Nf) - (B/Nb))/Af
CV = The precision value; 0.45 shall be used unless the
analytical laboratory provides the Contracting Officer
with documentation (Round Robin Program participation
and results) that the laboratory's precision is better.
AC = Effective collection area of the filter in square millimeters
V = Air volume sampled in liters
E = Fiber density on the filter in fibers per square millimeter
F/Nf = Total fiber count per graticule field
B/Nb = Mean field blank count per graticule field
Af = Graticule field area in square millimeters
TWA = C1/T1 + C2/T2 = Cn/Tn
Where: C = Concentration of contaminant
T = Time sampled.
SECTION 13280A
Page 56
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