EP 1110-1-23
31 Jan 99
TABLE A-1
FORMULA FOR CALCULATION OF THE 95 PERCENT CONFIDENCE LEVEL
(Reference: NIOSH 7400)
Fibers/cc (01.95 percent CL) = X + [(X)(1.645)(CV)]
Where:
X = ( (E) (AC) ) / ( (V) (1000) )
E = ( (F/Nf) - (B/Nb) ) / Af
E=
Fiber density on the filter in fibers per square millimeter
V = Air volume sampled in liters
AC = Effective collection area of the filter in square millimeters
Af = Graticule field area in square millimeters
CL = Confidence Level
CV = The precision value; 0.45 will be used unless the analytical laboratory
provides the CO with the documentation (Round Robin Program participation and results) that
the laboratory precision is better.
F/NF = Total fiber count per graticule field
B/Nb = Mean field blank count per graticule field
A-11
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