HEALTH AND SAFETY ASBESTOS GENERAL GUIDANCE

Transcription

1 HEALTH AND SAFETY ASBESTOS GENERAL GUIDANCE PERSONNEL DIVISION REVIEWED SPRING TERM 2000

2 Contents Page 1 Introduction 1 2 Where You Are Likely To Find Asbestos 2 3 Identifying Asbestos 3 4 Control Limits 4 5 Typical Exposures 5 i

3 1 Introduction This guidance is intended to assist in the appreciation of the risks posed by asbestos and legal and university standards relating to asbestos. Other relevant university documents are 'Contractors Code of Safe Practice', 'The Asbestos Management System' and 'Managing Asbestos Removal Contractors'. Breathing in asbestos dust can kill by causing irreversible lung damage and cancer. There is no known cure for asbestos related diseases. The more asbestos inhaled the greater the risk. Persons most at risk are building services tradespersons. In the university all work which is likely to generate asbestos dust is required to be carried out safely by a licensed contractor. If you are in doubt contact the Health and Safety Unit. Using licensed contractors assists in meeting the legal requirement to prevent exposure to asbestos. 'Control of Asbestos at Work Regulations 1987 (as amended 1998) (CAWR) - Approved Code of Practice' covers most general work with asbestos that does not include disturbance of insulation materials or major work with asbestos insulating board. Work with asbestos insulation and asbestos coatings, and major work with asbestos insulating board, are covered by a separate ACOP `Work with Asbestos insulation, asbestos coating and asbestos insulating board'. 1

4 2 Where You Are Likely to Find Asbestos 2.1 As asbestos insulation or coating used for: a) thermal insulation of boilers, ancillary plant and pipework (it may be hidden in underfloor pipe ducts); b) fire protection of structure steelwork (often hidden behind false ceilings); c) thermal and acoustic insulation of buildings (often hidden behind false ceilings); d) some textured coatings and paints. 2.2 As asbestos insulating board is used in a wide variety of places such as: a) fire protection on doors, protected exists, structural steelwork etc; b) cladding on walls, ceilings etc; c) internal walls and partitions; d) ceiling tiles in a suspended ceiling. 2.3 As asbestos cement which is found as: a) corrugated sheets (roofing and cladding of buildings); b) flat sheeting for partitioning, cladding and door facings; c) rain water goods (i.e. gutters, downpipes). 2

5 3 Identifying Asbestos The presence of asbestos may be indicated in the asbestos register held by Estates Planning Services or on original building plans or specifications. If it is not clear whether insulating material, boarding etc. contains asbestos, bulk sampling and laboratory analysis is necessary. This must be done by someone with suitable training and experience. Contact the Health and Safety Unit for assistance in taking samples. Alternatively you may assume that the material contains crocidolite (blue) or amosite (brown) asbestos and take appropriate precautions. Asbestos building boards are medium density and have a calcium silicate or cement base. The boards which were used in the considerable majority of building installations had the brand names Asbesotoluc, LDR, Marinite and Turnabestos. The asbestos content varied according to the brand but amosite (brown) was a common constituent, usually between 16% and 25%. Some boards included chrysotile (white). The principal types of asbestos are: Chrysotile - white in colour Amosite - grey or fawn in colour Crocidolite - blue in colour Asbestos building boards in situ should not be a cause for concern unless they are being damaged by abrasion or impact. If asbestos building boards are removed, they should be replaced with non-asbestos equivalent, i.e. Masterboard, Supalux, Tacfire, Monolux, Flax Board etc. 3

6 4 Control Limits The Regulations set control limits and action levels for asbestos. Control limits are expressed as concentrations of airborne fibres averaged over any continuous 4 hour or 10 minute period. Action levels are expressed as cumulative exposures over any continuous period of 12 weeks. The average level of asbestos fibre in the air inhaled by anyone must not exceed the control limits. The action levels trigger the operation of some of the CAWR: those dealing with notification, medical surveillance and designation of work areas. All of these limits may be exceeded during work with asbestos insulation board and cement. However unless the construction activity involves insulation removal work or some `major work', with asbestos insulating board, it is unlikely that the action levels will be exceeded. The more occasional the work the less likely it is that exposure will be greater than the action level. Work should be considered as major if action levels or control limits are likely to be exceeded during the work. Control Limits Chrysotile 0.3 fibres/ml over four hours. 0.9 fibres/ml over 10 minutes. Chrysotile with any other form of asbestos 0.2 fibres/ml over four hours 0.6 fibres/ml over 10 minutes Action Levels Chyrsotile 72 fibre hours per milliletre Chrysotile with any other form of asbestos 48 fibre hours per milliletre 4

7 5 Typical Exposures during Certain Works Asbestos Insulation Boards Careful removal of whole asbestos insulation boards (unscrewing with shadow vacuuming with spray application of a wetting agent on unsealed surfaces: Up to 3 fibres/ml Careful removal of whole boards (no LEV, no wetting): 1-5 fibres/ml Breaking and ripping out boards (dry with no unscrewing): 5-20 fibres/ml Drilling boards overhead (No LEV): 5-10 fibres/ml Drilling vertical columns (No LEV): 2-5 fibres/ml Jig sawing asbestos insulation board (No LEV): 5-20 fibres/ml (LEV) 1-5 fibres/ml Hand sawing asbestos insulation board (No LEV): 5-10 fibres/ml Rough handling: > 15 fibres/ml Scribing and breaking asbestos insulation board: 1-5 fibres/ml N.B. please note that where poor techniques are used very high exposures can occur e.g. breaking and ripping out dry with no unscrewing. Also note that exposures are likely to be higher where insulation board contains crocidolite or amosite asbestos or where the board is in poor condition. Cement Pipes and Sheets a Machine cutting without LEV i Abrasive disc cutting fibres/ml ii Circular saw fibres/ml iii Jig saw 2-10 fibres/ml b c d e f g Machine sawing with LEV < 2 fibres/ml Reciprocating saw < 1 fibres/ml Hand sawing < 1 fibres/ml Machine drilling < 1 fibres/ml Removal of asbestos cement sheeting < 0.5 fibres/ml Stacking of asbestos cement < 0.5 fibres/ml 5

8 h i Remote demolition of asbestos structures < 0.1 fibres/ml (CAUTION: subsequent clearance may give rise to concentrations greater than 1) Cleaning of asbestos cement: Roofing Vertical cladding Dry brushing (wire) Wet brushing (wire) Water-jetting (Note: water jetting may produce debris and slurry which is difficult to control.) N.B. These figures are the concentrations found when the processes are carefully carried out. Bad handling practices may result in higher concentrations. 6