Document 6DEdOO9BoZBBqp8RxGwxo02R

FILE NAME: Sprayed Asbestos (SPRA) DATE: 1972 DOC#: SPRA030 DOCUMENT DESCRIPTION: ILO Report - Practical Methods for Protection of Men Working with Asbestos Materials in Shipyards  C C U P A T I OINJAL S A F E T Y AND HEALTH SERIES SAFETY AND HEALTH IN SHIPBUILDING AND SHIP REPAIRING IN T ! PMAT i n r \) A| I fl R U H R n ('-F |p f C E N E V ^ - 19 ? P ; ? ENVIRONMENTAL HYGIENE venting dispersal of asbestos dust by sealing plastic ng damp insulation material. The bags are tagged for ite. The materials remain damp for easy installation. ble table fitted with downdraft ventilation. Suitable 1 sawing materials at shipside or aboard ship, ship vacuum cleaners act as ventilation source. 93 PRACTICAL METHODS FOR PROTECTION OF MEN WORKING WITH ASBESTOS MATERIALS IN SHIPYARDS A.A. Cross et al Abstract The Asbestosis Research Council was set up by leading asbestos companies in the United Kingdom in 1957 to carry out and sponsor research into the nature, cause and prevention of disease related to the inhalation of asbestos dust. In addition to its medical and scientific research projects, it has established an Environmental Control Committee to investigate and develop methods of practical control and safety in all those situations where materials contain ing asbestos could be used in a manner likely to produce potentially harmful quantities of dust. A report is given of the results of a particular study made of those situations where special difficulties occur through the space limitations of the working area. The aim of the study was to identify the type of product and the work patterns and situations where these difficulties mainly occurred, to collect information as to practical methods of control which have been devised, and to check on the effectiveness of such methods in reducing the exposure of operatives to acceptable standards. * * * Introduction The Asbestosis Research Council was formed in 1957 by the three major asbestos companies in the United Kingdom as a co-operative research organisation to prosecute a programme of research into the causation and prevention of asbestosis. Chairman, Environmental Control Committee, Asbestosis Research Council, United Kingdom. ENVIRONMENTAL HYGIENE ;he Environmental Control Committee of the ARC, through its is Working Groups, attempts to establish and recommend safe lg methods appropriate to different types of materials and rent areas of use. In the case of ship construction, the Qstances are highly specialised and in some respects exceptional, is evidence that the incidence of asbestos-related disease ship workers is higher than in most other areas of use. fie have tried in the first instance to identify the environmental tions which have given rise to this situation in the United am. We have then sought out the practical experience of users is industry in the development of methods of working which have tively reduced the level of exposure, and we have considered at extent experience in the asbestos industry itself and of of asbestos products in other sectors may be applied to the it of workers in ship construction and repair. It is hoped in ourse to assemble information about these practices in the form e of the ARC's series of Control and Safety Guides. al environmental conditions Cases of disease reported so far are likely to have had their n in operating conditions before the early 1950s, and, in the of mesotheliomas, in even earlier periods - perhaps 40 years It is necessary, therefore, to consider the kind of materials were being used during those years and the way in which work arried out. In early years these materials were, particularly for naval Is, mainly mattresses made of crocidolite (blue) asbestos cloth d with crocidolite fibre. Pre-formed sectional insulation .ining amosite or chrysotile was increasingly used from the late : until the early 1960s. Sprayed asbestos - mainly crocidolite ncreasingly used from the middle 1940s. In the past ten years, half of the new cases of asbestosis in IK have come from the insulation side of the industry. Applicaof sprayed asbestos and of pre-formed insulation in the very icted areas of ships' quarters resulted in the build-up of concentrations of dust, though nothing like the levels ienced in stripping. The conditions occurring in shipyards, especially naval dockcan be seen to have been made exceptionally hazardous by an 'tunate combination of several adverse factors. These are, the need to work in often extremely confined and restricted itions where many of the services used in factories for dust :tion or control are not available; second, the prevalence ;rto of particularly friable materials; third, operations, such mapping, which create excessive dust; fourth, extensive use of 'ticular type of asbestos - crocidolite - believed to be lially associated with mesothelioma. All of these factors appear ve combined to create an exceptional and persistent hazard affecting workers not directly involved in the manipulation of itos materials. PROTECTION OP MEN WORKING WITH ASBESTOS MATERIALS 95 The situation today Non-asbestos materials are now used for thermal insulation, and sprayed asbestos is rarely used, at least in British shipyards, unless predamping is employed. Nevertheless, as long as ships are in service in which these materials have been used in the past, stripping will occur, with its attendant dust problem. The materials which continue to be used do not pose such difficult problems of control. In the United Kingdom, control by exhaust ventilation or' the provision of personal protection is required if the asbestos dust level exceeds 2 fibres/ml (or 0.2 fibres/ml in the case of crocidolite). Many asjo.estos-containing materials in regular use do not come into this category and are regarded as "non-dusty". Some others, under certain conditions, can give rise to dust above this level; in many of 'these cases it has been found possible to devise methods of working or to devise equipment which adequately controls the dust level (see table l). Control and safety measures . Stripping. The operation presenting the most difficult problem for dust control is stripping off old insulation, whether this consists of sprayed asbestos or pre-formed insulation. Techniques developed in the British naval dockyards and by major users and contractors on industrial installations have relied onvthree basic methods, namely, enclosure; suppression by wetting; and personal protection. The effect of wetting has been reported to reduce concentrations in the working area, but this technique has been abandoned in British naval yards as creating too many other problems, except in the control of waste during disposal. Enclosure of the area, for example with polythene sheeting, combined with a ventilation system creating negative pressure can limit the contaminated area. One manufacturer is hopeful of develop ing a wet stripping machine incorporating a dust-proof debris receptacle. To date, however, operatives engaged in stripping must be equipped with positive-pressure respirators conforming to British Standard 4275, or air-line breathing apparatus, and with protective clothing completely covering the body from ankle to neck, as well as head covering. A hood incorporating the face-piece of the respirator or breathing apparatus has been found to be comfortable to wear and acceptable for men working in restricted areas over quite long work periods. Strict standards of hygiene must be observed, particularly in clearing up stripped material during and upon completion of the work, and for disposal of the collected waste in impermeable containers such as heavy plastic bags. Sprayed asbestos coatings. The application of sprayed asbestos coatings has been classified as an operation producing heavy concentrations, not only in -the operator's breathing zone but also in adjacent areas. Concentrations of as much as 1,500 fibres/ml have been reported, though a level of 200-300 fibres/ml is more 98 ENVIRONMENTAL HYGIENE Table 3 ASBESTOS DUST LEVELS IN VARIOUS INSULATION PROCESSES INVOLVING THE USE OP ASBESTOS CLOTH Operation Pitting asbestos cloth over primary lagging containing 15$ asbestos Pitting asbestos cloth over non-asbestos primary lagging Stripping insulation consisting of 100$ asbestos primary lagging covered with asbestos cloth Stripping insulation consisting of non-asbestos primary lagging covered with asbestos cloth Waking mattresses with asbestos filling Waking mattresses with mineral wool filling Ripping cloth P.G. Harries S. Holmes Asbestos dust concentration (fibres/ml) With conventional asbestos cloth With (a) dustsuppressed or (b) new process asbestos cloth up to 61 (average of 50 tests 10.5) 5-10 (a) 1-3 (b) 0.2-1.5 up to 3 021 (average of 211 tests 159) (b) 0.5-1.2 up to 126 (average of 23 tests 14.4) 6.6 (b) 0.2-1.5 >1 Fire-resisting board materials. These materials nowadays probably constitute the main asbestos product used in ship construction and are of special significance in view of their value for the protection of life at sea. They usually contain 25 to 40 per cent of asbestos, and may be used for bulkheads in board form, or, with special finishes of veneer or plastic sheeting, to form the decorated wall panels of cabins and accommodation quarters generally. When these materials are cut or drilled with power tools, relatively high concentrations of dust can be produced. Manufacturers of these I PROTECTION OF MEN WORKING WITH ASBESTOS MATERIALS 99 materials in the United Kingdom have introduced methods of surface sealing, hut while these have resulted in some reduction in dust arising from handling the hoards, they have not effected an improve ment in the dust levels from cutting and drilling. It has heen shown, however, that hy the development of suitably designed tools equipped with local exhaust ventilation, the level of dust in the f operator's breathing zone can be controlled to a considerable } extent. Ideally, panels should be cut to the sizes and shapes required ' ready for fitting with the minimum of adjustment on the vessel under construction. If materials cannot be obtained from the manufacturers ready cut, then a workshop should be set up on shore suitably equipped with dust extraction equipment. Such equipment, when properly designed and operated, will reduce dust levels to the extent that personal protection is not necessary. Even when these arrangements are made, it is not always possible to avoid some final cutting to fit. Occasional hand cutting or drilling will only produce moderate amounts of dust. Nevertheless it is recommended that respirators should be worn when this work has to be done in confined spaces. Suitably shrouded tools for cutting and drilling have been designed which can be connected to portable dust extraction equipment. Such equipment is capable of controlling the dust to levels where respiratory protection is no longer required. Tests carried out by official assessors have confirmed that levels lower than 5 fibres/ml may be expected when performing cutting and drilling with these tools. The equipment can also be used for vacuum cleaning purposes and is relatively inexpensive (see table 4). One of the larger British shipyards has established a special on-shore cutting shop equipped with saws, Sanders and veneering equipment and with an exhaust ventilation installation guaranteed to control the concentrations of asbestos dust at not more than 2 fibres/ml. The same yard has also established standard working practices for joiners fitting non-combustible asbestos boards on ships under construction. These practices provide for the use of portable vacuum cleaners for cleaning working areas, for de-dusting clothing of workmen at the end of the working period, and for providing local exhaust ventilation when occasional cutting has to be done. The arrangements also include the provision of a segregated area on the ship at a point convenient for the joinery work. This is simply done by the erection of screens made up of battens and EVC sheeting. It provides in effect an on-ship workshop equipped with a power saw fitted with a dust extraction device as well as vacuum equipment for collecting spilt sawdust and chippings. It has been found that by the use of properly designed dust extraction devices, the carefully planned supply of materials involving minimum on-site fabrication, and the maintenance of goodstandards of industrial hygiene, incombustible board materials can be worked without creating hazardous quantities of dust. It has also been found that, in carrying out these measures, the amount of labour involved in shipboard work has been considerably reduced. ^his saving can more than compensate for the cost of such relatively inexpensive equipment as has been described. ion ENVIRONMENT AL HYGIENE Table 4 VARIOUS OPERATIONS WITH INCOMBUSTIBLE BOARDS OR PANELS Operation Asbestos dust concentrations (fibres/ml) * A test room investigation Other reported counts without dust with dust without dust with dust extraction extraction extraction extraction Hand sawing Unveneered Veneered 31.4 58.4 3.4 13.8 to 44.8 - 1.1 - - Power hand saw Unveneered Veneered Bench saw Unveneered Veneered Power drill Unveneered Veneered >200 - >100 - 1.9 1.0 1.6 87 1.5 - 63 to 109 1.7 4.5 109 to 186 1.5 - - 1.4 0.9 - -- 0.7 5.4 - * These counts have been reported by various investigators under varying conditions, but the ARC's membrane sampling method has been used in all cases. Conclusion More work must be done in the development of tools which do not produce dust or which are equipped with efficient dust extraction devices. There is scope for further improvement in the development of dust-suppressed materials. Possibly one of the most important areas for improvement is in the raising of standards of hygiene and in the education of all those concerned - both management and workers - in adhering to the working procedures and safety standards devised for their protection. It will not be easy to maintain a consistent level, particularly since neglect produces no immediate penalty. Only by continual vigilance and a sustained educational effort will the desired standard be achieved. We believe that the methods of control we have reviewed and recommend are practicable and that time will show these to have been effective, so that the important part played by asbestos materials in shjp construction, particularly for the safety of those who go PROTECTION OF MEN WORKING WITH ASBESTOS MATERIALS I to sea, may continue to He enjoyed at no risk to those who build the ships. Acknowledgments Much valuable help has been given in the preparation of this paper from manufacturers and users of asbestos materials in the United Kingdom. In particular, the assistance is gratefully acknowledged of Surgeon Commander P.G. Harries of the Royal Navy, Mr. Colin Douglas of Swan Hunter Limited, HM Factory Inspectorate, members of the Working Groups of the Environmental Control Committe and member companies of the Asbestosis Research Council.