ISO/TC 146/SC 3/WG 1 - Determination of asbestos fibre content

This document specifies a method using scanning electron microscopy for determination of the concentration of inorganic fibrous particles in the air. The method specifies the use of gold-coated, capillary-pore, track-etched membrane filters, through which a known volume of air has been drawn. Using energy-dispersive X-ray analysis, the method can discriminate between fibres with compositions consistent with those of the asbestos varieties (e.g. serpentine and amphibole), gypsum, and other inorganic fibres. Annex C provides a summary of fibre types which can be measured. This document is applicable to the measurement of the concentrations of inorganic fibrous particles in ambient air. The method is also applicable for determining the numerical concentrations of inorganic fibrous particles in the interior atmospheres of buildings, for example to determine the concentration of airborne inorganic fibrous particles remaining after the removal of asbestos-containing products. The range of concentrations for fibres with lengths greater than 5 µm, in the range of widths which can be detected under standard measurement conditions (see 7.2), is approximately 3 fibres to 200 fibres per square millimetre of filter area. The air concentrations, in fibres per cubic metre, represented by these values are a function of the volume of air sampled. The ability of the method to detect and classify fibres with widths lower than 0,2 µm is limited. If airborne fibres in the atmosphere being sampled are predominantly [8] can be used to determine the smaller fibres.

This document specifies a reference method using transmission electron microscopy for the determination of airborne asbestos fibres and structures in in a wide range of ambient air situations, including the interior atmospheres of buildings, and for a detailed evaluation for asbestos structures in any atmosphere. The method allows determination of the type(s) of asbestos fibres present and also includes measurement of the lengths, widths and aspect ratios of the asbestos structures. The method cannot discriminate between individual fibres of asbestos and elongate fragments (cleavage fragments and acicular particles) from non-asbestos analogues of the same amphibole mineral[13].

This document specifies a reference method using transmission electron microscopy for the determination of airborne asbestos fibres and structures in in a wide range of ambient air situations, including the interior atmospheres of buildings, and for a detailed evaluation for asbestos structures in any atmosphere. The specimen preparation procedure incorporates ashing and dispersion of the collected particulate, so that all asbestos is measured, including the asbestos originally incorporated in particle aggregates or particles of composite materials. The lengths, widths and aspect ratios of the asbestos fibres and bundles are measured, and these, together with the density of the type of asbestos, also allow the total mass concentration of airborne asbestos to be calculated. The method allows determination of the type(s) of asbestos fibres present. The method cannot discriminate between individual fibres of the asbestos and elongate fragments (cleavage fragments and acicular particles) from non-asbestos analogues of the same amphibole mineral[12].

ISO 22262-3:2016 is primarily intended for quantitative analysis of samples in which asbestos has been identified at estimated mass fractions lower than approximately 5 % by weight. ISO 22262-3:2016 extends the applicability and limit of detection of quantitative analysis by the use of simple procedures of ashing and/or acid treatment prior to XRD quantification. ISO 22262-3:2016 is applicable to the asbestos-containing materials identified in ISO 22262‑1. The following are examples of sample matrices: a) any building materials in which asbestos was detected by the analysis in ISO 22262‑1; b) resilient floor tiles, asphaltic materials, roofing felts and any other materials in which asbestos is embedded in an organic matrix and in which asbestos was detected when using ISO 22262‑1; c) wall and ceiling plasters, with or without aggregate, in which asbestos was detected when using ISO 22262‑1. If non-asbestiform serpentine or non-asbestiform amphibole minerals are included in the matrix, the XRD peaks that are assumed to be "possible peaks of asbestos" will represent these minerals. This method is not for application to natural minerals that may contain asbestos or any products that incorporate such natural minerals. This method is intended only for application to building material samples that contain deliberately added commercial grade asbestos including tremolite asbestos. ISO 22262-3:2016 is intended for use by analysts who are familiar with X-ray diffraction methods and the other analytical procedures specified in the References [5] and [6]. It is not the intention of this part of ISO 22262 to provide basic instruction in the fundamental analytical procedures.

This International Standard specifies a method using scanning electron microscopy for determination of the concentration of inorganic fibrous particles in the air. The method specifies the use of gold-coated, capillary-pore, track-etched membrane filters, through which a known volume of air has been drawn. Using energy-dispersive X-ray analysis, the method can discriminate between fibres with compositions consistent with those of the asbestos varieties (e.g. serpentine and amphibole), gypsum, and other inorganic fibres. Annex C provides a summary of fibre types which can be measured. This International Standard is applicable to the measurement of the concentrations of inorganic fibrous particles in ambient air. The method is also applicable for determining the numerical concentrations of inorganic fibrous particles in the interior atmospheres of buildings, for example to determine the concentration of airborne inorganic fibrous particles remaining after the removal of asbestos-containing products.
The range of concentrations for fibres with lengths greater than 5 µm, in the range of widths which can be detected under standard measurement conditions (see 6.2), is approximately 3 fibres to 200 fibres per square millimetre of filter area. The air concentrations, in fibres per cubic metre, represented by these values are a function of the volume of air sampled. NOTE The ability of the method to detect and classify fibres with widths lower than 0,2 µm is limited. If airborne fibres in the atmosphere being sampled are predominantly 0,2 µm in width, a transmission electron microscopy method such as ISO 10312 can be used to determine the smaller fibres.

ISO 14966:2002 specifies a method using scanning electron microscopy for determination of the concentration of inorganic fibrous particles in the air. The method specifies the use of gold-coated, capillary-pore, track-etched membrane filters, through which a known volume of air has been drawn. Using energy-dispersive X-ray analysis, the method can discriminate between fibres with compositions consistent with those of the asbestos varieties (e.g. serpentine and amphibole), gypsum and other inorganic fibres. Annex C provides a summary of fibre types which can be measured. ISO 14966:2002 is applicable to the measurement of the concentrations of inorganic fibrous particles in ambient air. The method is also applicable for determining the numerical concentrations of inorganic fibrous particles in the interior atmospheres of buildings, for example, to determine the concentration of airborne inorganic fibrous particles remaining after the removal of asbestos-containing products. The range of concentrations for fibres with lengths greater than 5 micrometres, in the range of widths which can be detected under standard measurement conditions, is approximately 3 fibres to 200 fibres per square millimetre of filter area. The air concentrations, in fibres per cubic metre, represented by these values are a function of the volume of air sampled. NOTE The ability of the method to detect and classify fibres with widths lower than 0,2 micrometres is limited. If airborne fibres in the atmosphere being sampled are predominantly less than 0,2 micrometres in width, a transmission electron microscopy method such as ISO 10312 can be used to determine the smaller fibres.

Specifies a reference method using transmission electron microscopy for the determination of the concentration of asbestos structures in ambient atmospheres and includes measurement of the lengths, widths and aspect ratios of the asbestos structures. The method allows determination of the types of asbestos fibres present. The method cannot discriminate between individual fibres of the asbestos and non-asbestos analogues of the same amphibole mineral.