Document 6bkxeZERYLJVmRY1OrNaG2dZm

o Guidance Note EH 10 from the Health and Safety Executive environmental Hygiene/10 {revised April 1983) Asbestos control limits and measurement of airborne dust concentrations These Guidance Notes are published under five subject headings Medical, Environmental Hygiene, Chemical Safety, Plan? and Machinery and Genera!. INTRODUCTION 1 This Guidance Note is a revision of Environmental Hygiene/10 (December 19761, Asbestos - hygiene standards and measurement of airborne dust concent' rations- It replaces the information given in die earlier document and it secs out in para 9 the control limits recommended by the Advisory Committee on Asbestos (ACA)* which have been agreed by the Heal th and Safety Commission in the light of information available to them. The ACA believed that it was inappropriate to continue to control exposure levels in terms of a "'hygiene standard' as has been done hitherto. They believed that as the objective to be achieved was the controlled and progressive reduction of the levels of exposure, the term 'hygiene standard' should be replaced by 'control limit'.* 2 (? gives guidance on the exposure criteria the Health and Safety Executive's inspectors wit! use In determining whether, in their opinion, certain of the requirements of the Asbestos Regulations 1969* (particularly Regulation 7 and B) and Sections 2,3 and 4 of the Health and Safety at Work etc Act 1974J are observed. 11 is of course for the Courts alone to give a binding decision on the inter pretation of the law. 3 The Health and Safety Commission are considering further measures for the control of exposure to asbestos dust, in addition, the methods of measurement are under review. If further changes ore to be made, this document will be revised. 4 Part 1 deals with current legislation andcontrol limits. Parts 2 and 3 explains how the necessary measurements may be made. `Coftwauertfly the title of mis evidence Note Is altered hem the previous edition in this respect. The senes n-jmwr EH 10 is refined. PART 1 LEGISLATION AND APPROVED C006 OF PRACTICE5 5 The Asbestos Regulations 1969 apply to ail factories and to other premises to which Part IV of the Factories Act 1961 applies, including construction sites, electrical stations and ships under construction or repair etc, where a process involving asbestos is undertaken, except a process in which asbestos dust cannot be given off. 'Asbestos dost' is defined in Regulation 2 as "dust consisting of or containing asbestos to such an extent as is liable to cause danger to the health of employed persons". In determining whether "asbestos dust cannot be given off", the test should be applied before pre cautions are taken, for example, before local exhaust ventilation is provided. 6 Where the Asbestos Regulations do not apply, there is a duty under the Health and Safety at Work etc Art 1974 (WSW Act) to ensure, so far as is reasonably practicable, the health, safety and welfare of persons at work 8nd to protect persons no? at work against risks to health or safety arising out of or in connection with the activities of persons at work, and similar standards to the Asbestos Regulations should be adopted. 7 The Approved Code of Practice Work with asbestos insulation end asbestos coating* provides practical guidance on th* relevant legislation concerning the risk to health from asbestos during work with thermal and acousticinsulation includingstructural fire protection and sprayed coating. Medical evidence 8 A relationship between exposure to asbestos dust and asbestosis, asbestos related bronchia) cancer and mesothelioma has been recognised for many years. Th* Health and Safety Commission's Advisory Committee on Asbestos reviewed in 1976 79 all the evidence available to it at that time relating to the health risks of different types of asbestos. It concluded that there is evidence that at! types of asbestos fibre are associated with asbestos!*, cancer of the lung and gaiuo-imestinif tract, and mesothelioma (cancer of the lining of the chest and abdomen}. However, it appeared that a substantial proportion of mesotheliomas in this country are probably related to exposure to crccidofjte (blue asbestos} or smosite (brown asbestos). The ACA concluded that exposure to chrysotile alone has rarely been shown to cause mssothefioma. However, It considered that any change in industrial practice in the direction of tire production of more finely divided chrysotile fibre is likely to increase the health nsk. As far as cancer is concerned, the ACA concluded that there is an increase in risk with increasing dose, but that for ail types of asbestos, 'no safe level' of exposure could be identified. Further Information on the medical effects WV-15706 of workfng wi * different types of asbestos and heal* for the purpose of the Asbestos Regulations 1969 is precautions are set out in MSG Medical Series Guidance published every year is Form F24866. Only approved Nate MS 13, Asbestos5. equipment which is suitable for the anticipated 3 The Heal* and Safety Commission have decided that the following control limits, recommended by the Advisory Committee on Asbestos should be adopted wi* effect from 1 January 1993: conditions with a nominal efficiency such that the concentration of iseestos in the air breathed by the worker does not exceed the relevant contro* limit. Guidance on the selection, use, cleaning, maintenance and Storage of respiratory protective equipment is contained for dust consisting of or containing any crocidotite 0*2 fibre/ml when measured in the Approved Code of Practice Work with asbestos as a time'weighted average /nsu/et/onartf asbestoscoet/ng*. Additional guidance on over any 4-bour period the selection and use of respiratory protective equipment for dust consisting of or 0*5 fibre/mlwhen measured can bo obtained from local offices of the H$5, containing any amosite but not crocidolite for dust consisting of or as a time-weighted average over any 4>hour period l fibre/ml whin measured PART 2 MEASUREMENT OF AIRBORNE ASBESTOS containing other types of asbestos but not croctdolite or amoslte as a time-weighted average over any 4*hou period. General 16 Air monitoring is necessary to determine whether or 10 The control limits set out in para 9 do not represent site levels which once attained make further improve ments in dust control unnecessary. They recreant the uoper limit* of permitted exposure as determined by personal air sampling techniques (see paras 19 to 24} where there it still a statutory duty to reduce exposure to a lower level where this is reasonably practicable. not control of the personal exposure of workers to the relevant control limit for asbestos is being achieved; end also to identify those areas where Improvements in the system of work or engineering control equipment need to be made to ensure that the personal exposure of workers Is reduced to the minimum that is reasonably practicable. 11 The Health and Safety Executive will use the criteria set out in paras 3 and 10 in assessing whether there is a compliance wi* the relevant requirements of the Asbestos Regulations and the HSW Act, 12 For assessing compliance wi* the contiol limits, sampling should wherever possible, be carried out for the whole 4-hour period. However, where this is not reason ably practicable or appropriate, sampling should be carried cut for the actual period of exposure, and this result be used for assessing compliance as though the control limit was a time-weighted average for the period of sampling. Where both long-term and short-term samples covering the same 4-hour period are available {see para 131, the results of the long-term sample should be used for assessing compliance. 17 The air sampling strategy should be developed and executed by a person, or persons, who have adequate information, instruction and training for the task so that they cm cany it out effectively. Persons developing the strategy will need to be made aware of all asbestos processes at the workplace and will in particular need information and instruction about; (a) the plant and machinery used for transporting and preceding asbestos - containing materials: {b> the composition of materials {e,g, type of asbestos); (cl process details; and (dl individual employees' tasks. Membrane filter method for airborne asbestos dun 13 In order to comply wi* the statutory duty to reduce exposure to a lower level where this is reasonably practi cable. It Is necessaryto consider whether a further overall reduction in exposure can be achieved and, In particular, to identify any periods,of peak exposure. The identifi cation and evaluation of these peaks will reoulre sampling periods of lees than 4*oon. 19 Paragraphs 19 to 24 describe the method used to determine *e concentration of airborne asbestos dust to which persons are exposed at work. 19 Samples for assessment are taken by drawing a known volume of dust-laden air through a 25 mm diameter cellulose aster membrane filter of pom size 0*S to T*2 pm using a battery'Operated pump. The Engineering control and provision of respiratory protective equipment 14 These control limits need to be achieved by means of engineeringeonsrd where reasonably practicable. Where it is not reasonably practicable to maintain the personal exposure of the worker below the numerical control limits in para 9 by means of engineering controls then suitable approved respiratory protective equipment must be provided and worn. 15 A list of respiratory protective equipment approved membrane filter method is most accurate for deposit densities on ** filter of between tOO and 1000 fibres/ mm1. and this should be taken into account in choosing *e flowrate. For example, this density range would require a flowrate for a 4-hour sample onto a 25 mm filter from a concentration of 1 fibre/mi of between about 0*15 and 1*5 litm/min. The flow should be measured and controlled so that the accuracy of *e total volume sampled 4 known to within 5%. This normally requires the use of a calibrated flowmeter for all measurements. Any flowmeter built into *e pump C c c L SC-UK-MS-000057 *r>ay not be sufficiently accurate, t>us can still be used during sampling a$ an indicator that the instrument is working. 20 The filter holder should be of a design that will give a uniform deposit at the flowrate used. To minimise contamination, the filter should be loaded into the hofoers, unloaded and analysed in an area free from asbestos conlamination. The loaded heads should be covered with a protective cap during transport through asbestos-contaminated areas. *1 The pump should be attached to a loaded filter holder using flexible tubing, and the Flow adjusted to the chosen rate using * calibrated airflow meter. The pump should be allowed to run for 15 minutes before sampling to allow the Flowrate to steady - experience may show this to be unnecessary with some types of modern swb^ised /low pumps. A clean filter holder loaded with i clean filter should then be fitted and the Slow readjusted to the required rate. The pump should then be switched off and a protective cap fitted to the filter holder. 22 The filter holder should be fixed to die upper lapel w shoulder of the worker's clothing within 300 mm of his nose or mouth. Wherever possible, the same sampler position should be adopted for each worker. Some circumstances may lead to a higher concentration to be expected on one side of the worker than the other, in which case the sampler should bu positioned on the tide expected to give the higher result. At the start of the sampling period, the protective cap should be removed from the filter holder the pump started, and the time noted. The flowrate should be cheeked periodically fe,g, hourly) during sampling and readjusted to the eftosen rate. Operating experience may show this to be unnecessary with some types of pump, but it Is still advisable to check working conditions and that the equipment is functioning, Relevant information for use in interpreting the results fe.g. work In progress, conditions of plant) should be recorded during the sampimg period. At the endofdie period the time should be noted, die pump switched off, and the protective cap replaced on die filter holder. 23 After the sampling period, the filter may be earefuKy removed from its holder, and plead in a dean degreased tin or similar ftofder for transport. The clean, unrooted edge of the filter can be secured to the tin with adhesive tape, and subsequently removed with a surgical scalpel. Alternatively, the filter may be left in the holder, with the protective cep firmly in portion, for transport. r*fu*c&* of fempJer 24 The term fibre' referred to in para 9 means particles of length greater than 5 pm, diameter of less than 3 pm and having a length to breadth ratio of at least 3:1, observed by transmitted fight under phase contrast conditions at a magnification of approximately 500*. using a 40x objective with a numerical aperture of 0*65 - 0*70, against a background with r.i, between t *43 - V 60, The number of fibres conforming to this definition should be counted on a representative area of the filter using ohase contrast oot'C8i microscopy, and ihe airborne concentration calculates from the number counted, the area examined, tne area o* the filter, and the voigme of air collected The procedure is outlined in Technical Mote 1 of the Asbestosis Research Council', it is important to ensure that the microscope equipment is of satisfactory standard and is properiy adjusted (this can be checked with a phase contrast test slide I Other methods of monitoring airborne asbestos dust 25 Th$ control limits referred to m para 9 refer to the personal exposure of workers as determined by the method set out in paras 20 to 25. Additional valuable information can be obtained from other monitoring methods whichgive sn indication of the level and sources of airborne asbestos dust in the workpiece. 26 Instruments are available which give an immediate reading of the total dust concentration and are useful for providing an indication of the general dustiness of the air. Where itis possible to establish a correlation between the results of such instruments ana the membrane filter method in particular workplaces, the instruments can provide 4 rough and reedy measure of Hbesios dust w the air. For example, to iook for sources of dust emission, either from process plant or generated during manual handling, or to check that control equipment t* operating satisfactorily. Short-term static samples using the membrane filter method can provide similar information. 27 The dust lamp (a device for illuminating by forward scattering light) hasthe advantage, over other techniques, of making visible very fine dust particles thus enabling the observer to identify sources of dust emission and to follow movement Of the dust cloud. The method is described in Certificate of Approve! No API (F2363S*, Th dust lamp may be used in conjunction with video' equipment to enable a critical appraisal of existing work practices and engineering controls to identify ways of reducir^ dust emission. PART 3 SAMPLING AND ANALYSIS OF SULK MATERIAL 28 This Note now Outlines acceptable techniques for sampling and analysis of bulk materials for use with the Approved Code of Practice *V$r* mtb asbestos insufothn andasbestos coer/ng.* 29 Sampling and analysis of the bulk material is necessary fine, co determne* the presence of eebestoa and second, to Identify the type of asbestos. It it parti cularly important shat where any croctdolit* is present, the more stringent precautions should be applied and notification made in accordance with Regulation S of the Asbestos Regulations.5 If, however, employers find it more convenient to treat the material a* though it was crocidolite, and to provide precautions appropriate for this type of asbestos, then sampling and analysis need not be undertaken. SC-UK-MS-000058 30 The type and Quantity of esbesrot m o>a inuatliWA/ 2 The Asbestos Regulebom I $69, SM969 No 690 wrH frequently vary from one part to another, and it HMSO ISBN 0 51 090690 X is essential that the samples collected are representative. Sampling should take into account any apparent 3 Tbe Wealth ana SaUw ar Wo/k ere Ac* 1974, variations in the material including changes through the Chapter 37, depth of the insulating layer*. Those taking the samples HMSO ISBN 0 10 543774 3 must be protected from exposure to airborne asbestos dust. Soaking will greatly reduce the emission o? fibre 4 Health and Safety Commission. Work wiW asbestos du/>ng sampling. Wet bulk samples can be analysed in$uUtfon and asbestos coaling. Approved Code of without difficulty. The samples should be transported Practice and Guidance Note and text of trie Asbestos in sealed, impervious containers double if necessary, and Regulations and extracts from the Health and Safety adequately rdcrtffh'ed. at Work etc Act, (Revised June 19B3) 31 The types of asbestos present cannot readily be KMSO 1SBN0 11 633667 Q .;d*75?r#ied by the appearance or colour of the bulk 5 Keafdt and Safety Executive. Medkxl Series sample, particularly if other materials are present. Guidance Note MS13, Asbestos Damping the surface may help to locate areas containing HMSO (under revision) crocidolite (although the absence of blue colour does notguarantee absence of Crocidolite). Crocidolite may be 6 F2486 (1962) (revised) Certificate of approval significantly changed in appearance by the action of heat. (Respiratory Protective Equipment) 1932 Fibres can be identified using optical microscopy****, and an estimate of the proportion of the mineral* in the HMSO ISSN 0 11 883680 3 sample can be obtained using X*ay diffractioni941, Accurate X-ray diffraction measurement is difficult at 7 Technical Note 1 of the Asbestosi* Research Council. Arc, Sackville House, 40 Piccadilly, low levels (less than a few per cent) as it cannot in general distinguish between fibrous and non-fib+aut London WJV 9PA forms of mineral, so that this analysis should bo 6 F2363- Certificate of approval No API (particulars supported by a microscopical examination. Other to be contained in report of the result of thorough techniques, such as electros mcnjagopy a*d /rtfra-rsd examination and test of exhaust ventilation system) spectroscopy can also give useful information, HMSO IS6N011 383354 5 FURTHER AOVfCS 9 W MonkmaaAon, Occuo, Hyp., 22 (1979) 127-139 32 Anyone needjng further advice from the HSE on any aspects of this Guidance Note (e.g. training pt person* to carry out air sampling, obtaining suitable sampling equipment, identifying analytical laboratories) is advised to consult, his local HSS inspector who should be able to assist either directly or by putting the enquirer in touch w)jh in xiprc&riztM person. 10 Technical Note 3 of the Asbestosis Research Covnc AJC, SackwJle House, 40 Piccadilly, London W1V SPA ?? At 7*ytor, 77vA#*tysr, !03 J1978) 1009-!020 FURTHER INFORMATION REFERENCES 1 Health and Safety Commission. Asbestos -- Volume \Final Report of the Advisory-Committee HMSO tSQKO 1188)293 X This Guidance Note it produced by the Health and Safety Executive. Punher advice on this or any other publications produced by the Executive is obtainable from 9aynardj House, 1 Chepstow Place, London W2 4TF, or from Area Offices of the HSS. r c c HMSO Wo net ISSN O 11 883567 t Crown copyright 1983 First published 1977 2nd Fdition 1983 Primed m Engiancter HerMatest Ov koeender* Ltd. Atnersham D4 715295 C20Q 4/83 Stationer* 0<f<e c SC-UK-MS-000059