ASBESTOS and OTHER FIBERS by PCM: METHOD 7400, Issue 2, dated 15 August 1994 - Page 15 of 15
5. Count free ends of fibers emanating from large clumps and bundles up to a maximum of 10 ends (5 fibers), provided that each segment meets rules 1 and 2 above. 6. Count enough graticule fields to yield 200 ends. Count a minimum of 20 graticule fields. Stop at 100 graticule fields, regardless of count. 7. Divide total end count by 2 to yield fiber count. APPENDIX D. EQUIVALENT LIMITS OF DETECTION AND QUANTITATION Fiber density on filter*
Fiber concentration in air, f/cc
Fibers per 100 fields
Fibers/mm²
400-L air sample
1000-L air sample
200 100 LOQ 80.0 50 25 20 10 8 LOD 5.5
255 127 102 64 32 25 12.7 10.2 7
0.25 0.125 0.10 0.0625 0.03 0.025 0.0125 0.010 0.00675
0.10 0.05 0.04 0.025 0.0125 0.010 0.005 0.004 0.0027
- Assumes 385 mm² effective filter collection area, and field area = 0.00785 mm², for relatively “clean” (little
particulate aside from fibers) filters.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition
