Understanding Asbestos: Properties, Health Risks, and Safety Measures

1. 7. ASBESTOS 7. Asbestos

2. Introduction • Asbestos exists in many different forms but essentially a SILICEOUS material with a FIBROUS molecular structure. It is the only naturally occurring INORGANIC FIBER. • It has: extremely good durability and chemical resistance, and can be heated to high temperature without melting or burning. • In the direction of fibers, it has high strength. 7. Asbestos

3. Types of Fibers There are 3 main types of fibers; • Chrysotile • Crocidolite • Amosite • All of them are metamorphic origin. • Metamorphic rocks are formed when igneous, sedimentary, or othermetamorphic rocks undergo a physical change due to extreme heatand pressure. These changes often produce folded layers or banding inthe rocks, and they can also cause pockets of precious minerals toform. The folds and banding can be produced by incompletesegregation of minerals during recrystallization, or they can be inherited from preexisting beds in sedimentary rocks or pre-existinglayers in igneous rocks. The precious minerals can form as the resultof recrystallization when the rocks undergoing metamorphism aresubjected to changes in pressure and temperature. 7. Asbestos

4. Properties of fibers; Chrysotile; (Mg3Si2O5(OH)4) contains small amounts of aluminium, iron and sodium. • It has good heat-resistance, being resistant to attack by alkalis, is very suitable for use with Portland cements, as in asbestos-cement products. • The fibers are longest and have a silky white appearance. They are by far the most widely used. Crocidolite (blue asbestos); contains more iron than chrysolite, has greater strength and acid resistance and has a characteristic blue color. Amosite; contains relatively long, stiff but brittle fibers and is very suitable for insulating boards. 7. Asbestos

5. All fibers are very fine, as low as 0.1 m diameter, hence very high aspect ratios (l/d) and bond well to most matrices. 7. Asbestos

6. Properties of Fibers • Embrittlement of asbestos fibers may begin at temperature as low as 300oC, due to loss of water on crystallization, decomposition into simpler products occurring progressively up to about 1000oC. • Fusion is complete by about 1500oC, depending on type. • Part of the fire-proofing ability of asbestos products is that, rather like wood, the decomposed material provides effective insulation to underlying layers in a fire with additional benefit of non-compustibiliy. 7. Asbestos

7. Milling of fibers • Asbestos fibers are milled before use to break down them into finer and hence more efficient forms. • The effect of milling can be checked by measurement of specific surface, rather like cement. • Values of 5000 m2/kg are typical. 7. Asbestos

8. Health Hazard • It is unfortunate that asbestos particles may seriously affect the health of those who are in prolonged contact with the material. • It can cause “lung cancer”. This is due to inhalation of fibers. • Stringent regulations now apply in areas where asbestos dust may be present. These require the provision of respirators, protective clothing and exhaust ventilation. • Special storage and waste-disposal facilities are necessary in particular situations. • The most harmful type, CROCIDOLITE, may be recognized by its blue color. • CHRYSOTILE and AMOSITE are generally white and brown, respectively. 7. Asbestos

9. It is now also appears that there is some risk from asbestos products in use, mainly those which are not strongly bound, such as sprayed or low-density products. • Fibers can be released from these materials on aging, so it is advisable to have all such materials correctly removed. 7. Asbestos

10. Assessment of Health Risk • The risk associated with any mineral fiber is greatly influenced by its size, fibers of diameter below 2 m and length in the range 5-100 m generally being considered most harmful. • Larger fibers do not normally reach the sensitive lung tissues. • A typical safe level is considered to be 2 fibers/mm in working environments, with a reduction of 10 times for crocidolite. • Asbestos still has important applications in constructions where its excellent mechanical properties, combined with chemical and heat resistance, can be exploited without significant danger to health. • Safest products are those in which the fibers are tightly bound by a hard, abrasion resistance matrix. 7. Asbestos

11. Asbestos Cement (BS 690) • (short fibers) + (Portland cement) + (water) = = built up layers to form sheets mouldedcured • Silica and lime may be added during manufacture, • (short fibers) + (Portland cement) + (water) + (silica & lime)=steam autoclaved • Products are used externally; life  40 years. • During this time, impact strength decreases due to embrittlement (which also produces an increase in flexural strength). • Life can be prolonged by painting, an alkali-resistant primer being essential. 7. Asbestos

12. Uses of Asbestos Cement: • Many types of pipe, • In sheet or tile form, asbestos cement is available in fully-compressed (high density (1800 kg/m3), high bending stress (22.5 MPa) smooth surfaces on both face) or semi-compressed (density (1450 kg/m3), bending stress (16 MPa) states. • Flat sheets may be used for claddings, partition and ceiling linings. • Corrugated sheets have an advantage of increased rigidity for a given sheet thickness, • particularly suited to roofing and cladding of larger industrial and agricultural buildings. 7. Asbestos

13. Low Density Insulating Boards & Wallboards • Density  900 kg/m3 • Thermal conductivity  0.175 W/ moC Low Density Boards • Density; 900  d  1450 kg/m3 • Thermal conductivity  0.36 W/ moC Wallboards • Low Densityinsulating boards; traditionally used as surface membranes in roofs, walls, ceilings, partitions or as protection to structural steels. • Wallboards are used where greater mechanical resistance was required, such as on doors or as overlays for floors. These types represent a health hazard and currently available boards now contain non-asbestos substitutes, such as glass, cellulose, or polyvinyl alcohol. 7. Asbestos

14. Other Products of Asbestos • Asbestos in the form of chrysolite has excellent weaving ability and has been formed into FIRE BLANKETS, GLOVES, ROPES, SLEEVING etc. for heat/fire-resisting applications. • Although non-asbestos substitutes are now available, many of these are still in use. • Further applications include vinyl floor tiles, and damp-proof membranes, the health risk from such products being generally small. 7. Asbestos

15. Asbestos fiber 7. Asbestos

16. Control of Asbestos Regulations 2012 The Control of Asbestos Regulations 2012 link to external website came into force on 6 April 2012, updating previous asbestos regulations to take account of the European Commission's view that the UK had not fully implemented the EU Directive on exposure to asbestos (Directive 2009/148/EC). In practice the changes are fairly limited. They mean that some types of non-licensed work with asbestos now have additional requirements, ie notification of work, medical surveillance and record keeping. All other requirements remain unchanged. 7. Asbestos

17. What has stayed the same? • If existing asbestos containing materials are in good condition and are not likely to be damaged, they may be left in place; their condition monitored and managed to ensure they are not disturbed. • If you're responsible for maintenance of non-domestic premises, you have a 'duty to manage' the asbestos in them, to protect anyone using or working in the premises from the risks to health that exposure to asbestos causes. • If you want to do any building or maintenance work in premises, or on plant or equipment that might contain asbestos, you need to identify where it is and its type and condition; assess the risks, and manage and control these risks. 7. Asbestos

18. The requirements for licensed work remain the same: in the majority of cases, work with asbestos needs to be done by a licensed contractor. • This work includes most asbestos removal, all work with sprayed asbestos coatings and asbestos lagging and most work with asbestos insulation and asbestos insulating board (AIB). • If you are carrying out non-licensed asbestos work, this still requireseffective controls. • The control limit for asbestos is 0.1 asbestos fibres per cubic centimetre of air (0.1 f/cm3). • The control limit is not a 'safe' level and exposure from work activities involving asbestos must be reduced to as far below the control limit as possible. • Training is mandatory for anyone liable to be exposed to asbestos fibres at work. • This includes maintenance workers and others who may come into contact with or disturb asbestos (eg cable installers), as well as those involved in asbestos removal work. 7. Asbestos

19. What has changed? • From 6 April 2012, some non-licensed work needs to be notified to the relevant enforcing authority. • From 6 April 2012, brief written records should be kept of non-licensed work, which has to be notified eg copy of the notification with a list of workers on the job, plus the level of likely exposure of those workers to asbestos. • This does not require air monitoring on every job, if an estimate of degree of exposure can be made based on experience of similar past tasks or published guidance. • By April 2015, all workers/self employed doing notifiable non-licensed work with asbestos must be under health surveillance by a Doctor. Workers who are already under health surveillance for licensed work need not have another medical examination for non-licensed work. BUT medicals for notifiable non-licensed work are not acceptable for those doing licensed work. • Some modernisation of language and changes to reflect other legislation, eg the prohibition section has been removed, as the prohibition of supply and use of asbestos is now covered by REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals Regulations 2006). 7. Asbestos

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21. Asbestos cement panels 7. Asbestos

22. Asbestos cement pipes 7. Asbestos

23. brake pads electrical wires covered with asbestos 7. Asbestos

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25. ASBESTOS REMOVAL 7. Asbestos