ASTM-D7200 2006

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D7200-06 Standard Practice for Sampling and Counting Airborne Fibers, Including Asbestos Fibers, in Mines and Quarries, by Phase Contrast Microscopy and Transmission Electron Microscopy

Published By	Publication Date	Number of Pages
ASTM	2006	24

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Categories: 13.040.30 - Workplace atmospheres, ASTM

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Description

ASTM D7200-06

Historical Standard: Standard Practice for Sampling and Counting Airborne Fibers, Including Asbestos Fibers, in Mines and Quarries, by Phase Contrast Microscopy and Transmission Electron Microscopy

ASTM D7200

Scope

1.1 This practice describes the determination of the concentration of fibers, expressed as the number of such fibers per millilitre of air, using phase contrast microscopy and optionally transmission electron microscopy to evaluate particulate material collected on a membrane filter in the breathing zone of an individual or by area sampling in a specific location. This practice is based on the core procedures provided in the International Organization for Standardization (ISO) Standard ISO 8672(1), the National Institute for Occupational and Health (NIOSH) Manual of Analytical Methods, NIOSH 7400 (2), and the Occupational Safety and Health Administration (OSHA) Method ID 160 (3). This practice indicates the important points where these methods differ, and provides information regarding the differences. However, selecting portions of procedures from different published methods generally requires a user to report that they have used a modification to a method rather than claim they have used the method as written. This practice further gives guidance on how differential counting techniques may be used to indicate where a population of fibers may be asbestos.

1.2 The practice is used for routine determination of an index of occupational exposure to airborne fibers in mines, quarries, or other locations where ore may be processed or handled. The method gives an index of airborne fiber concentration. The method provides an estimate of the fraction of counted fibers that may be asbestos. This practice should be used in conjunction with electron microscopy (See Appendix X1) for assistance in identification of fibers.

1.3 This practice specifies the equipment and procedures for sampling the atmosphere in the breathing zone of an individual and for determining the number of fibers accumulated on a filter membrane during the course of an appropriately-selected sampling period. The method may also be used to sample the atmosphere in a specific location in a mine or in a room of a building (area sampling).

1.4 The ideal working range of this practice extends from 100 fibers/mm² to 1300 fibers/mm² of filter area. For a 1000-L air sample, this corresponds to a concentration range from approximately 0.04 to 0.5 fiber/mL (or fiber/cm³). Lower and higher ranges of fiber concentration can be measured by reducing or increasing the volume of air collected. However, when this practice is applied to personal sampling in mines and quarries, the level of total suspended particulate may impose an upper limit to the volume of air that can be sampled if the filters produced are to be of appropriate particulate loading for fiber counting.

1.5 Users should determine their own limit of detection using the procedure in Practice D 6620. For reference, the NIOSH 7400 method gives the limit of detection as 7 fibers/mm² of filter area. For a 1000-L air sample, this corresponds to a limit of detection of 0.0027 fiber/mL (or fiber/cm³). For OSHA ID 160 the limit of detection is given as 5.5 fibers/mm² of filter area. For a 1000-L air sample, this corresponds to a limit of detection of 0.0022 fiber/mL (or fiber/cm³).

1.6 If this practice yields a fiber concentration that does not exceed one-half the permissible exposure limit or threshold limit value for the particular regulated fiber variety, no further action may be necessary. If the fiber concentration exceeds one-half of the regulated permissible exposure limit or threshold limit value for the particular regulated fiber variety, examine the data to determine if more than 50 % of the counted fibers may be bundles, fibers longer than 10 μm, or fibers thinner than 1.0 μm. If these counts exceed 50 % of the total count, then there is an increased possibility that asbestos is present in the sample. Use the optional method specified in Appendix X1 to measure the concentration or proportion of the fibers counted that is of the regulated variety. If asbestos fibers are identified by this method, the mine/quarry operator should conduct a geological survey of the property to identify the source of the fibers.

1.7 The mounting medium used in this practice has a refractive index of approximately 1.45. Fibers with refractive indices in the range of 1.4 to 1.5 will exhibit reduced contrast, and may be difficult to detect.

1.8 Fibers less than approximately 0.2 μm in diameter may not be detected by this practice. (4)

1.9 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 7.

Keywords

air monitoring; asbestos; fibers; membrane filter method; mines and quarries; phase contrast microscopy; sampling and analysis

ICS Code

ICS Number Code 13.040.30 (Workplace atmospheres)

DOI: 10.1520/D7200-06

PDF Catalog

PDF Pages	PDF Title
1	Scope
2	Referenced Documents Terminology
3	Summary of Practice Significance and Use
4	Interferences Precautions Apparatus Reagents Sampling
5	Sample Preparation
6	Microscope Calibration Measurement
7	Calculations
8	FIG. 1
9	Sampling and Analytical Errors Precision and Bias TABLE 1
11	Quality Assurance FIG. 2
12	Keywords A1. SPECIFICATION AND CALIBRATION OF EYEPIECE GRATICULE A1.1 FIG. A1.1
13	A1.2 A1.3 Specification of Eyepiece Graticule FIG. A1.2
14	A1.4 A2. CALIBRATION OF THE LIMIT OF VISIBILITY USING THE HSE/NPL TEST SLIDE A2.1 A2.2 FIG. A2.1
15	A3. FIBER COUNTING CRITERIA FOR ASBESTOS (“A” RULES) A3.1 FIG. A3.1
16	A4. DIFFERENTIAL FIBER COUNTING A4.1 A4.2 A4.3 A4.4 TABLE A3.1
17	X1. IDENTIFICATION AND COUNTING OF PCM-EQUIVALENT FIBERS BY TRANSMISSION ELECTRON MICROSCOPY X1.1 Scope X1.2 Applicable documents X1.3. Terminology
18	X1.4 Summary of Method X1.5 Significance and Use X1.6 Interferences X1.7 Apparatus
19	FIG. X1.1
20	FIG. X1.2
21	X1.8 Reagents X1.9 Preparation of TEM specimens
22	X1.10 Measurement
23	X1.11 Calculations X1.12 Quality Assurance X1.13 Precision and Bias
24	REFERENCES

Additional information

Standard Title	D7200-06 Standard Practice for Sampling and Counting Airborne Fibers, Including Asbestos Fibers, in Mines and Quarries, by Phase Contrast Microscopy and Transmission Electron Microscopy
Published Code	ASTM
Publication Date	2006
Pages Count	24
ICS Codes	13.040.30 - Workplace atmospheres