ASTM D6058-96(2016)

Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment

SIGNIFICANCE AND USE
5.1 The SCCW may be present in the workplace atmosphere where these materials are manufactured, processed, transported, or used. The test methods discussed in this practice can be used to provide guidance when monitoring airborne concentrations of SCCW in these environments.  
5.2 Because of their visibility limitations, a significant fraction of the very small thin fibers that are present in some samples may not be detected by PCM or SEM. Therefore, TEM is considered to be the reference technique for the analysis of airborne SCCW. The TEM must be used to determine both fiber count and morphology when samples are from previously uncharacterized workplaces or materials.  
5.3 Although TEM is the reference technique, PCM or SEM are considered to be the primary screening methods for the analysis of airborne SCCW.  
5.4 Parallel TEM measurements shall be carried out, at least initially, to provide an index or relative measure of the fraction of total fibers that are seen by PCM or SEM. Only in instances when this percentage has been shown to be at a high and reproducible level may the lower resolution techniques (that is, PCM or SEM) be relied on exclusively.
SCOPE
1.1 This practice is intended to assist individuals in the sampling and analysis of single-crystal ceramic whiskers (SCCW), such as silicon carbide and silicon nitride, in the workplace environment. It describes sampling and analytical techniques used to assess the airborne concentration and size distribution of SCCW, which may occur in and around the workplace where these materials are manufactured, processed, transported, or used.  
1.2 The protocols currently in use for asbestos and other fibrous materials have been used as a guide in developing sampling and analytical procedures for characterizing fibers produced from the manufacture and use of SCCW. The sampling and analysis protocols described here have been written specifically for SCCW, however, they may be appropriate for other man-made mineral fibers (MMMF).  
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.4 This standard does not purport to address all of the safety concerns, if any, 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.

General Information

• Status: Published
• Publication Date: 30-Sep-2016
• ICS: 13.040.30 - Workplace atmospheres
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.07 - Sampling, Analysis, Management of Asbestos, and Other Microscopic Particles

Relations

• Replaces: ASTM D6058-96(2011) - Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment
• Effective Date: 01-Oct-2016
• Refers: ASTM D1356-20a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Sep-2020
• Refers: ASTM D1356-20 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Mar-2020
• Refers: ASTM D1356-15a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Oct-2015
• Refers: ASTM D1356-15 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Jul-2015
• Refers: ASTM D1356-14b - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Dec-2014
• Refers: ASTM D1356-14a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-May-2014
• Refers: ASTM D1356-14 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Jan-2014
• Refers: ASTM D6056-96(2011) - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Transmission Electron Microscopy (Withdrawn 2020)
• Effective Date: 01-Oct-2011
• Refers: ASTM D6059-96(2011) - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Scanning Electron Microscopy (Withdrawn 2020)
• Effective Date: 01-Oct-2011
• Refers: ASTM D6057-96(2011) - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy (Withdrawn 2020)
• Effective Date: 01-Oct-2011
• Refers: ASTM D1356-05(2010) - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Apr-2010
• Refers: ASTM D6056-96(2006) - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Transmission Electron Microscopy
• Effective Date: 01-Oct-2006
• Refers: ASTM D6059-96(2006) - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Scanning Electron Microscopy
• Effective Date: 01-Oct-2006
• Refers: ASTM D6057-96(2006) - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy
• Effective Date: 01-Oct-2006

Overview

ASTM D6058-96(2016) provides a standardized practice for determining the concentration of airborne single-crystal ceramic whiskers (SCCW) in workplace environments. SCCW, such as silicon carbide and silicon nitride whiskers, are man-made mineral fibers widely used in industrial applications due to their unique mechanical and thermal properties. However, understanding and controlling airborne SCCW concentrations is critical for occupational health and safety, particularly where these materials are manufactured, processed, transported, or used.

This ASTM standard outlines sampling and analytical techniques specifically tailored for characterizing airborne ceramic whiskers. It incorporates methodologies adapted from established asbestos monitoring protocols but is directly applicable to SCCW and can also be relevant for other man-made mineral fibers (MMMF).

Key Topics

• Sampling and Analysis Protocols

  • Describes procedures to collect and assess airborne SCCW using air sampling cassettes.
  • Defines criteria for fiber size, shape, and concentration measurements.

• Analytical Methods

  • Phase Contrast Microscopy (PCM): Primary screening method for larger-diameter fibers (>0.25 µm).
  • Scanning Electron Microscopy (SEM): Enables detection of thinner fibers (~0.1 µm diameter) and distinguishes SCCW from other fibers by elemental composition.
  • Transmission Electron Microscopy (TEM): Reference technique for overall fiber count, morphology, and for identifying fine-diameter fibers (<0.25 µm).

• Decision Criteria

  • Guidance on when to apply each analytical method.
  • Emphasis on using TEM for characterization in previously uncharacterized settings or where fine fibers are present.
  • Indexing and correlation of PCM and SEM results with TEM as a definitive reference.

• Quality Assurance

  • Recommends parallel testing and periodic verification with TEM to ensure screening methods remain accurate and representative.
  • Suggests ongoing control charting and periodic revalidation in response to process changes.

Applications

• Workplace Air Monitoring

  • Essential for health and safety monitoring in facilities manufacturing, handling, or using single-crystal ceramic whiskers.
  • Supports compliance with occupational exposure limits and proactive risk management.

• Industrial Hygiene and Safety Programs

  • Provides a standardized approach for hygienists and safety professionals to evaluate and control potential worker exposure to airborne SCCW.
  • Facilitates the accurate assessment of fiber concentration over time, ensuring that safety measures are based on reliable data.

• Research and Regulatory Compliance

  • Useful in studies assessing airborne man-made mineral fibers beyond SCCW.
  • Provides evidence-based methods to support regulatory submissions and workplace assessments governed by occupational health authorities.

Related Standards

• ASTM D1356: Terminology Relating to Sampling and Analysis of Atmospheres
• ASTM D6056: Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Transmission Electron Microscopy
• ASTM D6057: Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy
• ASTM D6059: Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Scanning Electron Microscopy

Practical Value

This standard practice offers clear protocols for monitoring the presence and concentration of single-crystal ceramic whiskers in occupational settings. By specifying the use of PCM, SEM, and TEM - with TEM as the reference method - it helps laboratories, industrial hygienists, and safety managers select the most appropriate analysis techniques for their specific requirements. This enhances workplace safety, aids regulatory compliance, and protects worker health when dealing with SCCW and related fibrous materials.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6058 − 96 (Reapproved 2016)
Standard Practice for
Determining Concentration of Airborne Single-Crystal
Ceramic Whiskers in the Workplace Environment
This standard is issued under the fixed designation D6058; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice is intended to assist individuals in the
D1356Terminology Relating to Sampling and Analysis of
sampling and analysis of single-crystal ceramic whiskers
Atmospheres
(SCCW), such as silicon carbide and silicon nitride, in the
D6056Test Method for Determining Concentration of Air-
workplace environment. It describes sampling and analytical
borne Single-Crystal Ceramic Whiskers in the Workplace
techniques used to assess the airborne concentration and size
Environment by Transmission Electron Microscopy
distribution of SCCW, which may occur in and around the
D6057Test Method for Determining Concentration of Air-
workplace where these materials are manufactured, processed,
borne Single-Crystal Ceramic Whiskers in the Workplace
transported, or used.
Environment by Phase Contrast Microscopy
1.2 The protocols currently in use for asbestos and other
D6059Test Method for Determining Concentration of Air-
fibrous materials have been used as a guide in developing
borne Single-Crystal Ceramic Whiskers in the Workplace
sampling and analytical procedures for characterizing fibers
Environment by Scanning Electron Microscopy
produced from the manufacture and use of SCCW. The
sampling and analysis protocols described here have been
3. Terminology
written specifically for SCCW, however, they may be appro-
3.1 For definitions of terms used in this practice, refer to
priate for other man-made mineral fibers (MMMF).
Terminology D1356.
1.3 The values stated in SI units are to be regarded as the
3.2 Definitions:
standard. The values given in parentheses are for information
3.2.1 man-made mineral fiber, n—any inorganic fibrous
only.
material produced by chemical or physical processes.
1.4 This standard does not purport to address all of the
3.2.2 single-crystal ceramic whisker, n—a man-made min-
safety concerns, if any, associated with its use. It is the
eral fiber that has a single-crystal structure.
responsibility of the user of this standard to establish appro-
3.2.2.1 Discussion—Although the terms fiber and whisker
priate safety, health, and environmental practices and deter-
are, for convenience, used interchangeably in this practice,
mine the applicability of regulatory limitations prior to use.
whisker is correctly applied only to single-crystal fibers
1.5 This international standard was developed in accor-
whereas a fiber may be single- or poly-crystalline or may be
dance with internationally recognized principles on standard-
noncrystalline.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Summary of Practice
mendations issued by the World Trade Organization Technical
4.1 This practice is based on a three-tier approach to the
Barriers to Trade (TBT) Committee.
quantitative assessment of airborne SCCW levels. It includes
detailed procedures to analyze standard air sampling cassettes
ThispracticeisunderthejurisdictionofASTMCommitteeD22onAirQuality
and is the direct responsibility of Subcommittee D22.07 on Sampling andAnalysis
of Asbestos. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2016. Published October 2016. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1996. Last previous edition approved in 2011 as D6058–96 (2011). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6058-96R16. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6058 − 96 (2016)
by phase contrast microscopy (PCM), scanning electron mi- (OSHA) for the monitoring of airborne asbestos in the work-
croscopy (SEM), and transmission electron microscopy place.Theasbestospermissibleexposurelimitandactionlevel
(TEM). arebasedonthistechnique.Thetestmethodwhichisdiscussed
in this practice, although closely related to the asbestos
4.2 The choice of a particular analytical method shall be
method, differs in that the counting rules recommended for
based on the visibility limitation of each instrument and an
SCCWare those described in NIOSH 7400 B. In contrast, for
understanding of the actual size distribution of the fibers being
asbestos the A Counting Rules are typically followed. Under
analyzed.
the NIOSH 7400 A Counting Rules, fibers with aspect ratios
4.3 Ingeneral,PCMissuitablefortheanalysisoffibersthat
≥3:1 are counted. The B Rules count fibers with aspect ratios
aregreaterthanapproximately0.25µmindiameter.Depending
≥5:1. The B Rules further place an upper limit on fiber
on the instrument and the sample preparation method used, the
diameterof3µm.TheBRuleswereselectedtomonitorSCCW
SEM may be capable of examining fibers as small as 0.10 µm
based on the nature of SCCWs which are not likely to split
in diameter. TEM has been shown to be suitable for the study
longitudinally as are asbestos fibers. While asbestos fibers of
of even finer fibers. The high resolution of this instrument
low aspect ratio, are, in reality, bundles of finer fibrils which
makes it well suited for the determination of the fraction of a
may split longitudinally into high aspect ratio fibrils, the
fiber population with diameters ≤0.10 to 0.25 µm.
SCCW do not have this structure and thus would not be
4.4 In addition to an enhanced image resolution, SEM and expected to split into higher aspect ratio fibers.
6.1.1.2 Inpractice,aportionofthemembranefiltercontain-
TEM have the further advantage of providing elemental
composition information on a single fiber. Furthermore, TEM ingtheairborneparticlesisplacedonaglassslideandrendered
transparent by exposure to acetone vapor. The slide is trans-
mayalsobeusedtoascertaincrystallographicdataonthefiber.
Thisadditionalinformationisfrequentlyhelpfulintheanalysis ferred to a phase contrast microscope and examined at a
magnification of approximately 400×. Fibers fitting the count-
of samples which contain numerous unknown fibers and, thus,
SEM or TEM, or both, are preferred in such instances. ing rules definition are counted if they lie within a measured
area. The B Rules require that fiber ends be counted and that
5. Significance and Use
this number then be divided by two to give the fiber count.
5.1 TheSCCWmaybepresentintheworkplaceatmosphere
From this fiber count, and knowing the volume of air sampled,
where these materials are manufactured, processed,
it is possible to calculate the fiber concentration in the air that
transported,orused.Thetestmethodsdiscussedinthispractice
was sampled. This number is generally expressed in terms of
can be used to provide guidance when monitoring airborne
fibers per millilitre (f/mL) of air.
concentrations of SCCW in these environments.
6.1.1.3 The PCM method only counts fibers that fit within
the dimensional constraints of the counting rules. Thus, the
5.2 Because of their visibility limitations, a significant
lower limit of length to be counted will be 5 µm and the
fraction of the very small thin fibers that are present in some
maximum diameter counted will be 3 µm. The lower limit of
samples may not be detected by PCM or SEM. Therefore,
diameter is determined by the resolution and contrast (visibil-
TEM is considered to be the reference technique for the
ity) of the microscope which is approximately 0.25 µm.
analysis of airborne SCCW. The TEM must be used to
6.1.1.4 ThePCMmethodisalsorestrictedtocountingfibers
determine both fiber count and morphology when samples are
of all types; the method does not identify or differentiate
from previously uncharacterized workplaces or materials.
betweendifferentfibertypes.Inconsequence,thePCMmethod
5.3 AlthoughTEMisthereferencetechnique,PCMorSEM
is applicable to measurement of those populations in which
are considered to be the primary screening methods for the
SCCWis the only, or the prevalent, fiber type present.The test
analysis of airborne S
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