Asbestos Facts

Introduction

What is Asbestos?
Asbestos is the term used for the fibrous form of a number of naturally occurring silicate minerals which have been exploited commercially for their useful properties of:

• Flexibility
• High tensile strength
• Incombustibility
• Low thermal conductivity
• Resistance to chemical attack

The three types of asbestos which have found significant industrial uses are amosite (brown asbestos), chrysotile (white asbestos) and crocidolite (blue asbestos). None of these minerals are found in commercial quantities within the UK, the bulk of the material used by industry having been imported from Canada or South Africa.

The maximum importation of asbestos into the UK occurred between 1970 and 1975. In total, over 5 million tonnes of asbestos has been imported into the United Kingdom.

Contents

1.0 The Main Properties of Asbestos
2.0 Asbestos Related Diseases
2.1 Asbestosis
2.2 Lung Cancer
2.3 Mesothelioma
2.4 Other Related Conditions
3.0 More about Asbestos Minerals
3.1 Chrysotile
3.2 Amosite
3.3 Crocidolite
3.4 Anthophylite
3.5 Tremolite and Actinolite
4.0 Asbestos in Buildings
5.0 Asbestos and the Law
6.0 The Asbestos Removal Industry
7.0 Protection during Asbestos Removal
7.1 Enclosures
7.2 Decontamination
7.3 Airlocks / Material Locks
7.4 Respiratory Protective Equipment
7.5 Further Control Measures
7.6 Air Monitoring
7.7 Occupational Control Limits
7.8 Medical Surveillance
8.0 Further Information

1.0 Main Properties of Asbestos

The physical and chemical properties of asbestos have determined its uses and commercial value. The very fine fibres of chrysotile and crocidolite are ideal for textile products. Their thermal stability makes the asbestos mineral useful in friction products and, together with their low thermal conductivity, in insulation materials. Asbestos cements made with chrysotile asbestos are high quality products because of the chemical bonding of the lime with the surface of the fibres.

The very properties which make asbestos a valuable raw material also create problems when it is inhaled; namely the ability of the fibres to split along their length into fine fibres that can reach the furthest part of the lung, and the resistance of the fibre to the chemical attack of the lungs defences.

Fine fibres are more likely to be inhaled than coarse fibres because they remain suspended in the air for longer. The thin fibres which are generated when asbestos is handled can penetrate deep into the lung where they can cause disease.

2.0 Asbestos Related Diseases

Asbestos has been used since pre-historic times. One of the earliest recorded uses was as lamp wicks. However, the real hazards were first recognised by the medical profession at the turn of the century when the first case of lung scarring, or asbestosis, was described. It was about 40 years before the first legislation was enacted to protect asbestos workers.

2.1 Asbestosis

This is a condition in which the lung becomes scarred as a result of prolonged inhalation of asbestos fibres. It only occurs in people exposed to relatively large amounts of asbestos, normally over many years, such as in milling, weaving, lagging or removal operations. The scarring is more properly known as fibrosis. The part of the lung which is damaged is at the far end of the smallest bronchial tubes, the place where the lung transfers oxygen to the blood stream.

The fine fibres, once in the lung, are not readily removed. In fact, in sufficient numbers, they are able to damage the scavenging cells that arrive to remove them and this leads to a process of 'healing' by scar formation of fibrosis.

Unfortunately, scar formation in the lung destroys useful lung tissue and ultimately may result in sufficient damage to impair the lungs ability to take up oxygen. This leads to the individual becoming short of breath and, as the disease progresses, may be responsible for his or her death.

In Britain, about 150 new cases of asbestosis are reported each year. It is dose related: that is, very high exposures, such as occurred before the 1950's, could produce the disease in three or four years, but lower exposures may take more than a working lifetime to cause it.

Once the disease has started, it usually progresses slowly, though there is some evidence that it may stop progressing if it is detected early and the person is removed from further exposure. It sometimes appears for the first time after the person has left the asbestos industry. As there is no known treatment and the disease is definitely progressive if found late, early detection is essential and all asbestos workers should have regular medical surveillance.

2.2 Lung Cancer

Lung cancer is a common and usually fatal type of cancer which occurs in about 30,000 people in Britain each year. Far and away the main cause is cigarette smoking.

However, it has been known from the 1940's and the 1950's that excessive numbers of asbestos workers die of this disease. The risk is such that a man with asbestosis who smokes 20 cigarettes per day has a 50% chance of dying of lung cancer.

Non-asbestos exposed 20 per day smoker, in contrast, has a 13% chance.

The evidence again suggests that the more asbestos a worker has been exposed to, the greater his risk of lung cancer.

Lung cancer usually progresses rapidly by spreading to new sites round the body and so far methods for early detection have proved unsuccessful in improving the outlook for patients. Occasionally, patients may be cured by major surgery, but essentially the hope for control of this disease lies in persuading people not to smoke. This applies with special force to asbestos workers.

2.3 Mesothelioma

This is a malignant incurable cancer of the outside lining of the lungs (called 'the pleura') or the lining of the bowels ('the peritoenum'). When it affects the pleura it causes pain in the chest and breathlessness, a chest x-ray will show signs of fluid and a tumour inside the chest wall. It progresses slowly over one to two years, making the patient suffer more and more pain, weight loss and results in eventual death.

A similar course is followed with peritoneal disease, though there is pain and swelling in the abdomen.

The disease usually develops between 20 and 50 years after exposure to asbestos first took place. This explains why the occurrence of Mesothelioma has been steadily rising in Britain over the last 20 years (the current yearly total has now reached more than 1,200 deaths from this disease alone), since the peak use of crocidolite in Britain occurred during and after the last war).

Latest estimates from the Health & Safety Executive indicate that the annual death toll from the above described conditions is now in the order of 3,000 and will continue to rise to a peak of 10,000.

2.4 Other Conditions Associated with Asbestos Exposure

Apart from the diseases discussed above, several other conditions may affect the pleural lining of the lung as a result of asbestos exposure; they are all relatively benign conditions. Pleural plaques are one of these conditions. These are harmless scars in the pleura that can be found in almost anyone who has been exposed to asbestos at work. They often show up on x-ray. More rarely, the pleura scars more extensively and this may cause some difficulty with breathing. If, as is only very rarely the case, it needs treatment, it can be removed by an operation. Very occasionally asbestos exposure causes fluid to accumulate around the lung (pleural effusion). This usually goes away by itself, or it can be removed easily with a needle.

Some other parts of the body are occasionally affected by asbestos. Corns may develop on the skin. There is also some evidence that cancers of the stomach, bowel and larynx (voice box) may occur more frequently in people who have in the past been heavily exposed to asbestos although the evidence is very ambiguous.

3.0 More about the asbestos minerals

3.1 Chrysotile

Chrysotile is the most widely used asbestos variety and is casually referred to as 'white' asbestos. It is a member of the group of minerals known as serpentine.

The serpentine group of minerals is very widespread in nature, areas of northern Britain contain large quantities. Fortunately, only the chrysotile occurs as a genuinely fibrous form and is much less common. Chrysotile is formed by hydro-thermal alteration of rocks rich in magnesium. In its raw state it is pale green, cream or white and it forms a mass of curly soft white fibres when processed. It is highly flexible which makes it ideal for spinning and weaving.

3.2 Amosite

The most common asbestos amphibole is amosite. Amosite is the commercial name derived from the acronym of Asbestos Mines of South Africa, the producers of the mineral. The mineral should more properly be called Grunerite. It is also known casually as 'brown asbestos'.

It occurs in veins in metamorphic iron rich rocks only in South Africa. It is coarser and stronger than chrysotile and forms more needle like fibres when processed. In the raw state it is dark brown or black but when processed it is grey-brown, or white if heavily milled.

3.3 Crocidolite

Crocidolite is the correct name for the amphibole asbestos commonly known as blue asbestos. Its primary source is in South Africa but was also produced in Wittenoom, Australia, or in a slightly different variety in Bolivia. It is blue-black in the raw state but when processed it forms fine fibres with a distinctive smokey blue colour.

3.4 Anthophylite

Anthophylite is a coarse white asbestos variety which was produced in Finland until the 1960's. It is not in widespread use and can only be found very occasionally in commercial products or lagging.

3.5 Tremolite and Actinolite

These are both quite rare as commercial asbestos minerals, although quite common as normal chrystalline minerals. Actinolite is green in colour. It is found in association with some of the other South African amphibole asbestos and it may be present as a contaminant in products manufactured with asbestos from that area.

Tremolite asbestos is produced in moderate quantities in Taiwan, Korea, Pakistan and India. It has in the past been produced in Italy. It consists of white silky fibres. It has not had widespread uses but can be found in commercial products.

Tremolite and Acinolite may occur as a trace contaminant in other mineral products like talc or vermiculite.

4.0 Asbestos in Buildings

Chrysotile is by far the most abundant asbestos form in terms of production and usage (about 93%). It can be found in a wide variety of products from yarn, rope and textiles to cement, insulation boards, friction materials, baskets and thermo-plastics.

Crocidolite had a similar widespread use although the tendency was to use it in mixtures with other asbestos varieties. Amosite, because of its coarser nature, tended to find greater use in asbestos boards and other rigid products. All 3 varieties may be found in all proportions in pipe and plant lagging.

The uses in building construction are divided into 10 broad categories:

• Spray coatings and laggings
• Insulating board
• Ropes, yarns and cloth
• Millboard, paper and paper products
• Asbestos cement products
• Bitumen felts and coated metals
• Flooring materials
• Texture coatings and paints
• Mastic, sealants, putties and adhesives
• Reinforced plastics

Spray coatings were used for anti-condensation and acoustic control or as fire protection on structural steel. They comprised a thin layer of cement and fibre mixture applied by high pressure spray. The main fibre type used was amosite although the other two main varieties can sometimes be found.

Laggings are found on boilers, pipes and other 'hot' items of plant. They may have been produced from pre-formed sections or toweled on from a thick cement mixture.

Insulating boards were manufactured from cement or calcium silicate and asbestos. They were produced to provide a low density, low cost fire resistant insulation. They can be found in a wide variety of buildings, both commercial and domestic.

Asbestos yarns were used in the manufacture of asbestos cloth for fire protection clothing, gloves and in fire blankets. They may also have been used in gaskets or packing materials. Asbestos millboard and papers were generally used for fairly specialist applications such as insulation of electrical equipment. They contain a high proportion of asbestos and may be easily damaged or abraded.

The fibre cement products produced with asbestos have had widespread use. They contain about 10% asbestos, mostly chrysotile but some crocidolite and amosite was used prior to 1976. They differ from the insulating boards in their density which is about two to three times higher.

The remaining applications, floor tiles, bitumen felts etc. have a much lower potential to release fibres and will generally not present a great problem in use.

Asbestos usage in equipment and appliances is divided into:

• Domestic appliances, such as cookers, washing machines
• House goods, kitchen mats and ironing board pads
• Fire blankets
• Heating systems
• DIY products

5.0 Asbestos and the Law

In the years following the recognition of asbestosis, legislation has been introduced to combat these newly recognised risks, the law has been progressively tightened with regulations in 1931 and 1969 and these have been further strengthened with the introduction of 5 new regulations since 1983. The key legislation is:

• The Control of Asbestos at Work Regulations 1987, revised in 1999
• The Asbestos (Licensing) Regulations 1983
• The Asbestos (Prohibitions) Regulations 1993
• The Asbestos Products (Safety) Regulations 1985
• The Control of Asbestos in Air Regulations 1990
• The regulations set out the specific rules for handling asbestos and are generated from more general health and safety legislation and detailed guidance material.
• The various documents are built up in various layers:
• Acts of Parliament - i.e. Health and Safety at Work Act
• Regulations - i.e. The Control of Asbestos at work Regulations
• Approved Codes of Practice and Guidance Note

Statute law is made by Parliament and is embodied in various acts. In the field of health and safety the prime examples are the Health and Safety at Work Act and the Factories Act.

There are two Approved Codes of Practice relevant to asbestos:

• The Control of Asbestos at Work
• Work with Asbestos Insulation, Asbestos Coating and Asbestos Insulation Board

At the last count there were more than 20 guidance documents dealing with asbestos.

6.0 The Asbestos Removal Industry

Asbestos removal as an industry largely came about in the mid 1970's as a result of an increased awareness of death and illness related to asbestos exposure, and changes in Health and Safety Law.

The industry itself was instrumental during the early years in introducing many of the techniques and methods we now regard as the norm - i.e. enclosures, suppressants etc. As the industry grew the Health and Safety Executive became more and more active in monitoring its progress, gradually introducing tighter controls.

The Asbestos Licensing Regulations 1983 were introduced to control companies engaged in asbestos removal operations until this time any individual, or group, could be employed to carry out asbestos removal works. As a result of the introduction of the licence requirements, many of the less established operators were quickly overtaken by more professional and responsible organisations.

The asbestos removal industry is now a highly specialised movement, employing carefully controlled processes endeavouring to ensure that no person is exposed to the hazards of asbestos inhalation.

7.0 Protection During Asbestos Removal Operations

Persons in charge of asbestos removal should evaluate each contract or task separately and appropriate removal techniques must be employed based on this evaluation.

7.1 Enclosures

An enclosure is a physical barrier erected around the asbestos works area which is sealed to minimise leakage so that, as far as possible, asbestos dust and waste arising from the work is prevented from spreading to the surrounding environment. Anyone working inside an enclosure must wear suitable protective clothing and respiratory protective equipment and must decontaminate themselves on leaving the enclosure.

7.2 Decontamination - Hygiene Facilities

A hygiene facility is any mobile, fixed or temporary facility which is provided to enable people removing asbestos insulation and asbestos coatings to change from normal outdoor clothing into protective clothing and respiratory protective equipment before entering the asbestos contaminated work area, and to effectively decontaminate themselves when leaving the work area.

7.3 Airlocks / Material Lock

All enclosures must have means of access/egress for personnel, plant and the removal of asbestos waste. Openings for these purposes are designed to prevent asbestos dust escaping into the general environment. Wherever practicable, asbestos workers will enter the enclosure directly through the hygiene facility. Where the hygiene facility cannot be positioned close to the enclosure an airlock system is set up and in this case operatives will 'transit' to the facility after an initial decontamination.

7.4 Respiratory Protective Equipment (RPE)

RPE is designed to be worn in a contaminated atmosphere and to provide its wearer with a filtered or direct supply of air. RPE includes a very wide range of devices, from simple respirators offering basic protection against low levels of harmful dusts, gases or micro-organisms, to self-contained breathing apparatus of the type used by fire brigades and others in emergency situations where the wearer would not be able to survive without the equipment.

RPE is considered as the 'last resort' as a means of preventing or controlling the exposure to substances hazardous to health. In some cases effective control of exposure will result from a combination of personal protection, such as RPE, and other methods.

7.5 Further Control Measures

Asbestos removal works should always be designed so as to:

• Eliminate breakage or unnecessary scraping, brushing or agitating of the asbestos material.
• Suppress asbestos materials and dust release effectively.
• Avoid working in hot or humid environments which may affect the integrity of RPE.
• Use localised air extraction methods at the stripping 'face'.
• Supply maximum negative pressure and ensure stripping works are always carried out upstream of the air flow.
• Avoid the use of power tools to aid in removal.
• Be correctly assessed for use of the most suitable RPE including, if necessary, 'air-fed' equipment.

7.6 Air Monitoring

The primary purpose of air monitoring is to protect the health of employees by determining or checking the concentrations of airborne asbestos to which they are exposed. Information on employee exposure is required for comparison with occupational exposure limits (OEL's) and any controlling assessment of risk.

Monitoring also offers further purposes when checking the integrity of asbestos removal enclosures and as final clearance indication following completion of asbestos removal works and prior to dismantling the enclosure.

Air monitoring will normally be carried out by an independent laboratory using the appropriate sampling equipment and microscopy techniques.

7.7 Occupational Control Limits

A control limit is a respirable concentration of asbestos in the air average over any continuous 4 hours or 10 minute period to which employees must not be exposed unless they are wearing suitable RPE. There are two sets of control limits and the set to be used depends upon the type of asbestos present during the work concerned.

There are control limits for chrysotile alone and others for the five forms of amphibole asbestos. The limits are for chrysotile alone:

• 0.3 fibres per ml of air averaged over any continuous period of 4 hours
• 0.9 fibres per ml of air averaged over any continuous period of 10 minutes for any other form of asbestos either alone or in mixtures
• 0.2 fibres per ml of air averaged over any continuous period of 4 hours
• 0.6 fibres per ml of air averaged over any continuous period of 10 minutes
• Action levels apply to exposure in the longer term and are cumulative exposure calculated over any continuous 12 week period. The action level result is fibre-hours per ml of air (fibre-hours/ml). The action levels are:
• Where the exposure is solely to chrysotile, 72 fibre-hours per ml of air
• Where exposure is to any other form of asbestos, either alone or in mixtures, including mixtures of chrysotile with any other form of asbestos, 48 fibre-hours per ml of air

7.8 Medical Surveillance

All asbestos workers are subject to a medical examination once every two years. The examining body will record details of the examination and the exposure. The records are quite separate from confidential clinical medical records.

8.0 Further Information

Further information relating to any Asbestos or Health and Safety issue can be obtained by contacting us.