Page:NIOSH Manual of Analytical Methods - 7400.pdf/1



ASBESTOS and OTHER FIBERS by PCM	7400 FORMULA: Various   MW: Various   CAS: see Synonyms   RTECS: Various METHOD: 7400, Issue 2

EVALUATION: FULL

OSHA:	 0.1 asbestos fiber (> 5 µm long)/cc; 1 f/cc, 30 min excursion; carcinogen MSHA:	 2 asbestos fibers/cc NIOSH:	0.1 f/cc (fibers > 5 µm long), 400 L; carcinogen ACGIH:	 0.2 f/cc crocidolite; 0.5 f/cc amosite; 2 f/cc chrysotile and other asbestos; carcinogen

Issue 1: Rev. 3 on 15 May 1989 Issue 2: 15 August 1994

PROPERTIES:	 solid, fibrous, crystalline, anisotropic

SYNONYMS [CAS #]:	actinolite [77536-66-4] or ferroactinolite [15669-07-5]; amosite [12172-73-5]; anthophyllite [7753667-5]; 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 SAMPLER:

FILTER (0.45- to 1.2-µm cellulose ester membrane, 25-mm; conductive cowl on cassette)

TECHNIQUE:

LIGHT MICROSCOPY, PHASE CONTRAST

ANALYTE:

fibers (manual count)

SAMPLE PREPARATION:

FLOW RATE*:	0.5 to 16 L/min VOL-MIN*: -MAX*:

MEASUREMENT

400 L @ 0.1 fiber/cc (step 4, sampling)
 * Adjust to give 100 to 1300 fiber/mm²

COUNTING RULES:

acetone - collapse/triacetin - immersion method [2] described in previous version of this method as “A” rules [1,3]

SHIPMENT:	 routine (pack to reduce shock) SAMPLE STABILITY:

stable

BLANKS:

2 to 10 field blanks per set ACCURACY

RANGE STUDIED:

80 to 100 fibers counted

BIAS:

see EVALUATION OF METHOD

EQUIPMENT:

1.	positive phase-contrast microscope 2.	Walton-Beckett graticule (100-µm field of view) Type G-22 3. phase-shift test slide (HSE/NPL)

CALIBRATION:

HSE/NPL test slide

RANGE:

100 to 1300 fibers/mm² filter area

ESTIMATED LOD:	 7 fibers/mm² filter area OVERALL PRECISION :	0.115 to 0.13 [1] ACCURACY:

PRECISION :

0.10 to 0.12 [1]; see EVALUATION OF METHOD

see EVALUATION 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 an index of airborne fibers. It is primarily used for estimating asbestos concentrations, though PCM does not differentiate between asbestos and other fibers. Use this method in conjunction with electron microscopy (e.g., Method 7402) for assistance in identification of fibers. Fibers < ca. 0.25 µm diameter will not be detected by this method [4]. This method may be used for other materials 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 particles 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