Asbestos Awareness 1. Introduction This presentation contains: The properties of asbestos Its effects on health Its interaction with smoking The types of product and materials likely to contain asbestos The operations that could result in exposure and the importance of prevention Safe working practices how to avoid the risks Emergency procedures 2. Properties of asbestos Asbestos is a naturally occurring mineral, with many physical forms, of which the three most important are: Amosite, brown asbestos Crocidolite, blue asbestos Chrysotile, white asbestos Asbestos is resistant to heat and not subject to chemical attack. It was valued for its insulating properties and its high tensile strength and was used extensively either as fibres and board, or mixed into other products (such as in vinyl floor tiles). The physical form is long thin fibres and fibre bundles. The fibres, once airborne, can be breathed in, and due to their shape they can be carried deep into the lungs. Nasopharyngeal region: air velocity is high, particles of approximate diameters 5-30 m are deposited Trachea and bronchial region: air velocity is slowing, particles 1-5 m are deposited Alveolar region: air velocity here is minimal and particles are deposited largely by diffusion. Gases, vapours and particles typically 2 m diameter or less reach this region. Fortunately a high proportion of submicron particles are breathed out before they get the chance to be absorbed.
When things are breathed in we have many defence mechanisms. In the upper regions of the airway there are hairs that line the passages, and mucus is exuded. The hairs waft the particles upwards and they are then coughed, sneezed or blown out. If particles reach the alveolar region, they are attacked by white blood cells (macrophages) which attempt to engulf the foreign particles and dispose of them. Unfortunately, the stiff, javeline-like asbestos fibres can penetrate the air sacs in the alveoli. They can be too long to be swallowed by the macrophages, and can rupture them. 3. The effects of asbestos on health and its interaction with smoking Inhalation of asbestos fibres is associated with three fatal diseases: Asbestosis a scarring of the lungs (not malignant) Lung, larynx and gastrointestinal cancers Mesothelioma a cancer of the lining around the lungs and stomach** These diseases can take from 15 to 60 years to develop. ** the current figures are almost 2000 deaths a year from mesothelioma, and asbestos-related deaths in total are currently around 3500 per year. The likelihood of developing disease as a result of exposure to asbestos depends upon: The type of fibre (blue and brown are more dangerous than white) Your age when you begin to be exposed (the likelihood increases if you are younger) The number of fibres breathed in The number of times exposed Smoking ** ** the risk to a smoker who is exposed to asbestos is greater than the sum of the risks from smoking and from asbestos in isolation. This latter point can be illustrated by some probabilities: Some estimated risks of lung cancer: Non-smoker, not working with asbestos 1 Non-smoker, working with asbestos 5 Smoker, not working with asbestos 10 Smoker, working with asbestos Up to 90 4. Typical uses of asbestos Some of the common uses of asbestos are: Asbestos cement sheeting for walls and roofs Asbestos cement products such as tiles, cold water tanks, pipes and gutters, artex Insulating board in wall partitions, fire doors, ceiling tiles, forges etc Yarns and textiles (fire blankets, asbestos string and paper for glassblowing) Lagging Sprayed coatings for insulation and decorative purposes Asbestos-reinforced plastics (floor tiles) Furnace linings It became apparent that the use of asbestos was associated with several serious diseases, and gradually the use of asbestos was phased out. The use of sprayed asbestos ceased in 1974 and asbestos-reinforced insulation board was phased out from 1980.
The importation, use and installation of amosite and crocidolite-containing materials has been prohibited in the UK since 1986 and the use of chrysotile was banned from 1999. So all asbestoscontaining materials are now historic. The following photographs show typical uses: Laggings and sprayed coatings Sprayed coatings could be 80-90% asbestos and loose coatings and laggings are high risk, Damaged asbestos pipe lagging and debris Damaged asbestos lagging on hot water pipes Wall with trowelled loose asbestos Insulating board: Asbestos insulating board (AIB) This could be 20-40% amosite (amphibole) Perforated AIB ceiling tiles damaged around the light fitting
Suspended AIB ceiling tiles in a corridor Cement products: Asbestos cement is approximately 10-15% asbestos Asbestos cement downpipe, hopper and profile sheet Damaged asbestos roof Textile products: Asbestos rope used as insulation on a pipe Pipe insulated using both asbestos rope and asbestos lagging
Asbestos fire blanket Products that contain asbestos, but have to be treated aggressively to release the fibres: Asbestos-containing floor tiles Etonite windowsill While most work with asbestos must be done by licensed contractors, a few low risk tasks can be done by others. However, there is a need for further training, special clothing and cleaning-up procedures, so it is our policy not to do any asbestos work at all. Unscrewing an AIB ceiling tile Careful removal of AIB ceiling tile
Common sites of asbestos in the Cavendish: Window sill Baton around ceilings Panel above windows Panels in stairwells
5. The operations that could result in exposure and the importance of prevention The primary cause of asbestos related disease is inhalation. Therefore undisturbed materials are not an immediate risk. Things that could increase that risk are: Drilling holes in them Breaking them or cutting them Knocking into them Sticking things to them and then pulling them off (sticky-fixers or blu-tack) Typical exposures Operation fibres/ml Dry removal of lagging up to 100 Drilling asbestos insulating board up to 10 Hand sawing asbestos insulating board up to 10 Sweeping asbestos insulating board debris up to 100 Drilling asbestos cement up to 1 Hand sawing asbestos cement up to 1 Using a circular saw on asbestos cement up to 20 The control limit 0.1 Notice that some of these exposures are not far above the control limit (= maximum exposure limit) and it is possible with suitable precautions to do certain of these operations without having to call in an asbestos contractor. However, our policy in the Cavendish is not to do this. How to avoid the risks Always check that a material is not asbestos before cutting it or drilling into it. We have an asbestos register (accessible by Keith, Peter and Jane) which can be consulted to give a pretty fair indication of the presence of asbestos, or not. We have a duty of care: To ourselves not to knowingly take risks with asbestos To our colleagues especially those who are new to the department or are young To contractors and other visitors, to warn them of the presence of asbestos and tell what not to do. 6. Emergency procedures What if.? you discover some asbestos that you did not know about? If possible, avoid disturbing it. Whether you can continue the job with it in place or not depends. Contact Peter Norman, Keith Matthews or Jane Blunt for further advice if it is in the way of what you want to do. What if.? Someone accidentally damages some asbestos?
Cordon off the area immediately (lock the door if possible) Tell Peter Norman, Keith Matthews and/or Jane Blunt If people have been contaminated with dust or debris then they need to be decontaminated and may need to see Occupational Health for counselling. To sum up: Do not carry out work on the fabric of the premises without checking with Keith/Peter/Jane Do not disturb asbestos-containing materials Report any damage or deterioration of asbestos-containing materials Stop and do this immediately if asbestos-containing materials have been inadvertently damaged.