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1、 Reference number ISO 14966:2002(E) ISO 2002 INTERNATIONAL STANDARD ISO 14966 First edition 2002-11-15 Ambient air Determination of numerical concentration of inorganic fibrous particles Scanning electron microscopy method Air ambiant Dtermination de la concentration en nombre des particules inorgan
2、iques fibreuses Mthode par microscopie lectronique balayage Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:46:10 MDTNo reproduction or networking permitted without license fr
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6、the address given below. ISO 2002 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below
7、 or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2002 All rights reserved Copyright International Organization for Standardizat
8、ion Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:46:10 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 14966:2002(E) ISO 2002 All rights reserved iii Contents Page Foreword iv Introduction. v 1 Scope
9、 1 2 Terms and definitions. 1 3 Abbreviated terms. 4 4 Principle . 5 5 Apparatus and materials 5 5.1 Air sampling. 5 5.2 Preparation of filters. 7 5.3 Sample analysis 8 6 Air sample collection and analysis . 9 6.1 Measurement planning. 9 6.2 Collection of air samples 9 6.3 SEM specimen preparation 1
10、0 6.4 Analysis in the scanning electron microscope 12 7 Calculation of results 23 7.1 Calculation of the mean fibre concentration 23 7.2 Calculation of the 95 % confidence interval. 24 8 Performance characteristics 24 8.1 General. 24 8.2 Measurement uncertainty. 25 8.3 Limit of detection 28 9 Test r
11、eport 29 Annex A (normative) Preparation of filters for air sampling 31 Annex B (normative) Procedures for calibration and adjustment of the SEM. 32 Annex C (informative) Characteristics and chemical composition of inorganic fibres. 34 Annex D (informative) Poisson variability as a function of fibre
12、 density on sampling filter and area of filter analysed 39 Annex E (informative) Combination of the results from multiple samples. 40 Bibliography 41 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for
13、 Resale, 04/07/2007 05:46:10 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 14966:2002(E) iv ISO 2002 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The w
14、ork of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-govern
15、mental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. The
16、 main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
17、 Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 14966 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC
18、 3, Ambient atmospheres. Annexes A and B form a normative part of this International Standard. Annexes C, D and E are for information only. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 0
19、4/07/2007 05:46:10 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 14966:2002(E) ISO 2002 All rights reserved v Introduction This International Standard describes a method for measurement of the numerical concentration of inorganic fibrous particles in ambient air using
20、 the scanning electron microscope. This International Standard is based on the procedures of Verein Deutscher Ingenieure (VDI) Guideline 3492 6. The method is also suitable for determining the numerical concentrations of inorganic fibres in the interior atmospheres of buildings, for example measurem
21、ent of residual airborne fibre concentrations after the removal of asbestos-containing building materials 7. Biological research has shown that the fibrogenic or carcinogenic effect of a fibre is related to its length, diameter and its resistance to dissolution in a biological environment. The point
22、 at which fibres are too short, too thick or of insufficient durability to produce a fibrogenic or carcinogenic effect is uncertain. Fibres with lengths greater than 10 m and diameters of a few tenths of 1 m, which also have durabilities such that they remain unchanged for many years in the body, ar
23、e regarded as particularly carcinogenic. On the basis of current knowledge, fibres shorter than 5 m are thought to have a low carcinogenic potential 8 to 11. For the purposes of this International Standard, a fibre is defined as a particle which has a minimum length to width (aspect) ratio of 3:1. F
24、ibres with lengths greater than 5 m and widths extending from the lower limit of visibility up to 3 m are counted. Fibres with diameters less than 3 m are considered to be respirable. Since the method requires recording the lengths and widths of all fibres, the data can be re-evaluated if it is requ
25、ired to derive concentrations for fibres with a higher minimum aspect ratio 12. The range of concentration to be measured extends from that found in clean air environments, in which the mean value of a large number of individual measurements of asbestos fibre concentrations has been found to be gene
26、rally lower than 100 fibres/m3 (fibres longer than 5 m), up to higher exposure scenarios in which concentrations as much as two orders of magnitude higher have been found 10, 12. This method is used to measure the numerical concentration of inorganic fibres with widths smaller than 3 m and lengths e
27、xceeding 5 m up to a maximum of 100 m. Using energy-dispersive X-ray analysis (EDXA), fibres are classified as fibres with compositions consistent with those of asbestos fibres, calcium sulfate fibres and other inorganic fibres. Calcium sulfate fibres are separated from other inorganic fibres and ar
28、e not included in the final result, because on the basis of current knowledge, they do not represent any health hazard. Nevertheless, the numerical concentration of calcium sulfate fibres must be determined, since a high concentration of these fibres can negatively bias the results for probable asbe
29、stos fibres, and in some circumstances the sample may have to be rejected 13. In addition, knowledge of the numerical concentration of calcium sulfate fibres is of importance in the interpretation of fibre concentrations in ambient atmospheres. Detection and identification of fibres becomes progress
30、ively more uncertain as the fibre width is reduced below 0,2 m. Identification of a fibre as a specific species is more confident if the source of emission is known or suspected, such as in a building for which bulk materials are available for analysis. In order to facilitate the scanning electron m
31、icroscope examination, organic particles collected on the filter are almost completely removed by a plasma ashing treatment. Except in situations where fibre identification is difficult, there should be only minor differences between fibre counting results obtained by this method and those obtained
32、using the procedures for determination of PCM-equivalent fibres in annex E of the transmission electron microscopy method ISO 10312:1995. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/
33、07/2007 05:46:10 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:46:10 MDTNo reproduction or networki
34、ng permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 14966:2002(E) ISO 2002 All rights reserved 1 Ambient air Determination of numerical concentration of inorganic fibrous particles Scanning electron microscopy method 1 Scope This International Standard specifies a method using sca
35、nning 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 meth
36、od 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 t
37、he 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 rema
38、ining after the removal of asbestos-containing products. The range of concentrations for fibres with lengths greater than 5 m, 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. T
39、he 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 m is limited. If airborne fibres in the atmosphere being sampled are predominantly (1) wi
40、th a minimum of 30 pulses in the channel corresponding to the maximum peak height for each of the magnesium and silicon peaks 16, and 2 PB B + (2) for each of the magnesium and silicon peaks. During analysis, each selected image field is examined for fibres of the length and width ranges specified i
41、n 6.4.2. Using EDXA, these fibres are then classified into compositional groups according to the criteria specified in 6.4.3. The sequential number of the image field, the fibre length, the fibre width, the elemental composition and the fibre classification are recorded on a fibre counting form. An
42、example of a suitable fibre counting form is shown in Figure 5. In order to document the appearance and particulate loading of the sample, three micrographs shall be taken of each sample and attached to the fibre-counting form. 6.4.2 Fibre-counting criteria 6.4.2.1 General Examine at least 50 image
43、fields in order to reduce, to the extent that is possible, the effect of fluctuations in the filter loading density on the counting result. Select image fields to be evaluated in such a way that the whole area of the sample is taken into account and overlapping of the image fields does not occur. Co
44、unt fibres in accordance with the specifications in 6.4.2.2 to 6.4.2.9, and the examples shown in Figures 6 and 7. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/07/2007 05:46:10 MDTNo
45、reproduction or networking permitted without license from IHS -,-,- ISO 14966:2002(E) ISO 2002 All rights reserved 13 FIBRE COUNTING FORM: ISO 14966 Sample No.: Date: Page No.: Name: Calcium sulfate Tally list: Rejected structures Tally list: Number of image fields Fibre No. Image field No. l m D m
46、Elemental composition Fibre type Tally list: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Chrysotile type fibres: Amphibole fibres: Number rejected: Bundles: Clusters: Matrices: Totals Other inorganic fibres: Calcium sulfate: Number of fibres without spectrum: Tot
47、al number of image fields: Number of image fields rejected: Calibrated magnification: Micrograph numbers: 1: 2: 3: Figure 5 Example of fibre counting form Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 No
48、t for Resale, 04/07/2007 05:46:10 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 14966:2002(E) 14 ISO 2002 All rights reserved 0 = Do not count 1 = Count Figure 6 Examples of fibres extending outside the image field Fibre: count as 1 Split fibre: count as 1 Fibre bundle: count as 1 Cluster: count as 3 Cluster: count as 5 Matrix: count as 1 (particle 3 m) Matrix: count as 2 (particle 2;