NYC 9/11 Public Portal Document
ASBESTOS and OTHER FIBERS by PCM 7400
Various MW: Various CAS: Various RTECS: Various
METHOD: 7400, Issue 2 EVALUATION: FULL Issue 1: Rev. 3 on IS May 1989
Issue 2: 15 August 1994
OSHA : 0.1 asbestos fiber (> 5 pm long)/cc; PROPERTIES: solid, fibrous, crystalline, anisotropic
1 f/cc/30 min excursion: carcinogen
MSHA: 2 asbestos fibers/cc
NIOSH: 0.1 f/cc (fibers > 5 pm long)/400 L; carcinogen
ACGIH: 0.2 crocidolite; 0.5 amosite; 2 chrysotile and other
asbestos, fibers/cc; carcinogen
SYNONYMS [CAS #]: actinolite [77536-66-4] orferroactinolite [15669-07-51; amosite [12172-73-5]; anthophyllite [77536-67-5];
chrysotile [12001-29-5]; serpentine [18786-24-8]; crocidolite [12001-28-4]; tremolite [77536-68-6]; amphibole asbestos [1332-21-4];
refractory ceramic fibers [142844-00-6]; fibrous glass.
SAMPLING MEASUREMENT
SAMPLER: FILTER TECHNIQUE: LIGHT MICROSCOPY, PHASE
(0.45- to 1.2-pm cellulose ester CONTRAST
membrane, 25-mm: conductive cowl on
cassette) ANALYTE: fibers (manual count)
FLOW RATE*: 0.5 to 16 Umin SAMPLE
PREPARATION: acetone - collapse/triacetin - immersion
VOL-MIN*: 400 L @ 0.1 fiber/cc method [2]
-MAX*: (step 4, sampling)
•Adjust to give 100 to 1300 fiber/mm COUNTING
RULES: described in previous version of this
SHIPMENT: routine (pack to reduce shock) method as "A" rules [1,3]
SAMPLE EQUIPMENT: 1. positive phase-contrast microscope
STABILITY: stable 2. Walton-Beckett graticule (100-pm
field of view) Type G-22
BLANKS: 2 to 10 field blanks per set 3. phase-shift test slide (HSE/NPL)
ACCURACY CALIBRATION: HSE/NPL test slide
RANGE STUDIED: 80 to 100 fibers counted RANGE: 100 to 1300 fibers/mm’ filter area
BIAS: see EVALUATION OF METHOD
ESTIMATED LOD: 7 fibers/mm’ filter area
OVERALL PRECISION (§,,.): 0.115 to 0.13 [1]
PRECISION (S3: 0.10 to 0.12 [1]; see EVALUATION
ACCURACY: see EVALUATION OF METHOD
OF METHOD
APPLICABILITY: The quantitative working range is 0.04 to 0.5 fiber/cc for a 1000-L air sample. The LOD depends on sample
volume and quantity of interfering dust, and is <0.01 fiber/cc for atmospheres free of interferences. The method gives a n index
of airborne fibers. It is primarily used for estimating asbestos concentrations, though PCM does not differentiate betwe en asbestos
and other fibers. Use this method in conjunction with electron microscopy (e.g., Method 7402) for assistance in identifi cation of
fibers. Fibers < ca. 0.25 pm diameter will not be detected by this method [4]. This method may be used for other materia Is such
as fibrous glass by using alternate counting rules (see Appendix C).
INTERFERENCES: If the method is used to detect a specific type of fiber, any other airborne fiber may interfere since all particles
meeting the counting criteria are counted. Chain-like particles may appear fibrous. High levels of non-fibrous dust part Ides may
obscure fibers in the field of view and increase the detection limit.
OTHER METHODS: This revision replaces Method 7400, Revision #3 (dated 5/15/89).
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition. 8/15/94
NYC-WTC_000149405
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