Asbestos is a heat-resistant fibrous mineral that naturally occurs in the ground. In fact, six different minerals can be described as ‘asbestos’ and are all known carcinogens. Its prolific use in the construction industry to provide fireproofing and insulation products, has meant that even though it was officially banned in this country in 1999, the danger to health is ongoing.
Although six minerals can be termed ‘asbestos’ the three main types used in the industry were chrysotile, amosite and crocidolite.
Chrysotile (white asbestos)
This is the last type of asbestos to be banned in the UK, and was the most widely used. Chrysotile fibres are fine and soft in nature, so it was often woven and spun into asbestos textiles such as fireproof blankets and safety clothing.
Chrysotile was historically the most common type of asbestos to be used by manufacturers around the world. Also known as white asbestos, it is part of the Serpentine family and has a different composition to crocidolite and amosite.
It can still be found in large quantities today, despite being banned in the UK in 1999. The substance was used in many hundreds of household items, as well as building materials such as asbestos cement.
How do chrysotile fibres differ from other forms of asbestos?
The fibres are softer than those in the amphibole group (brown and blue asbestos). They are curvy and less brittle, and this flexibility made them useful in the manufacture of fire-resistant clothing, fire blankets, and other types of protective work wear.
It is said the fibres are more readily expelled by the body if inhaled, when compared with their needle-like counterparts in the amphibole family. Having said that, chrysotile asbestos poses a serious health risk, and is the cause of many illnesses including pleural mesothelioma.
Malignant pleural mesothelioma aggressively attacks the outer lining of the lungs, and unfortunately life expectancy for patients is often only months. The long latency period of asbestos disease means that people may not be aware they have an asbestos-related illness for several decades – sometimes up to 60 years from the initial exposure.
Why was white asbestos so useful in manufacturing?
Chrysotile has a very high tensile strength, which combined with its flexible nature, made it useful for textile-based products. Its high resistance to heat and thermal insulating properties also provided fire resistance for industrial and commercial buildings.
The entertainment industry used the substance for acoustic purposes, as well as for fire-proofing and insulation. Theatre curtains commonly contained chrysotile, as did flooring and wallboards in theatres and cinemas.
Where else was chrysotile used?
One of the main products to contain chrysotile was asbestos cement. This is generally considered to be safe if intact as the cement bonds the asbestos particles together, minimising the likelihood of fibre release.
This low friability means that handling asbestos cement products can sometimes be graded as non-licensed work if the product remains intact. If not, the Health and Safety Executive may class it as notifiable non-licensed work (NNLW).
The widespread use of chrysotile in building and household materials means that significant amounts of this type of asbestos remain today. Among other products, it can be found in:
- Water tanks
- Asbestos insulation boarding
- Ceiling and floor tiles
- Partition walling
- Fire blankets
- Gutters and downpipes
- Roofing sheets
- Roofing shingle
- Chrysotile was also used by the automotive industry to make brake linings, clutches, brake pads and gaskets.
Although the import, export, and use of chrysotile have been banned in many countries, this type of asbestos remains a standard addition to construction and other materials in numerous developing countries.
Amosite (brown asbestos)
Amosite has long, thin and brittle fibres that are easily broken, and therefore readily inhaled. It is regarded as the second most dangerous type of asbestos, and was banned in this country in 1986.
Amosite is characterised by needle-like fibres that offer good resistance to heat, and have strong insulating properties. For these reasons, it was a common addition to construction materials in many countries around the world.
‘Amosite’ is actually an acronym and trade name for grunerite, a member of the amphibole group of minerals. It was largely mined in the Transvaal Province in South Africa, which is where the name originated – Asbestos Mines of South Africa (AMOSA).
This dangerous substance remains in many of our older buildings today, posing a danger to workers or members of the public undertaking DIY and refurbishment, renovation, or demolition work.
Anyone carrying out this type of work should undergo asbestos awareness training. It provides the knowledge needed to identify asbestos in its varying forms, and act in accordance with the Control of Asbestos Regulations, 2012.
Banned in the 1980s
In 1985 the Asbestos Prohibitions Regulations introduced a ban on amosite, along with crocidolite (blue asbestos). Amosite is generally considered to be the second most dangerous form of asbestos after crocidolite, and creates a high risk factor for life-threatening disease for anyone who has breathed in its fibres.
It is said that, when intact, asbestos does not pose a serious danger. Considering the length of time these asbestos-containing materials have been in place, however, even a small degree of disturbance to the fabric of an older building could release tiny fibres into the air.
Specific health risks of amosite
Being rod-like in nature, amosite fibres can easily penetrate the lung wall when breathed in, and offer a serious risk to health when airborne. The body finds it difficult to expel the fibres once inhaled, and life-threatening disease can be set up several decades later.
Life-limiting illnesses including asbestosis and pleural thickening, and terminal lung cancers, are caused by exposure to asbestos, sometimes decades before any of the symptoms are felt.
Products containing brown asbestos
Building products requiring high tensile strength were often manufactured using amosite. These included:
- Roof tiles
- Ceiling and floor tiles
- Cement sheets
- Electrical insulation
- Pipe lagging
- Chemical insulation
- Asbestos insulating board
Because of their resistance to fire, ceiling tiles containing amosite were commonly used in schools and other educational buildings, and have been the subject of debate for many years.
Crocidolite (blue asbestos)
Banned in the UK in 1985, Crocidolite is the most dangerous form of asbestos due to its particularly strong needle-like fibres that lodge within the lung linings when inhaled.
Crocidolite is a fibrous form of the mineral Riebeckite, and one of the six main types of asbestos. All six minerals that make up asbestos are characterised by fibrous crystals, which is the fundamental issue in relation to all associated health problems.
Also known as blue asbestos, crocidolite was mined in South Africa, Australia and Bolivia until the 1960s, and is widely thought to present the highest risk factor for all forms of asbestos due to its extremely strong needle-like fibres that are easily inhaled.
Crocidolite is categorised as an amphibole and its fibres, although brittle by nature, can be straight or curved. Products containing crocidolite have a high ‘friability’ rate, which means they break up easily when disturbed.
Crocidolite offers less resistance to heat than the other two main forms of asbestos. It was still used in industry, however, and remains present in thousands of household products.
The strength of the fibres, combined with its fire-retardant and insulating properties, made crocidolite a widely-used resource across many industries. Construction, automotive shipbuilding, and even the tobacco industry used the substance on a regular basis.
Lorillard Tobacco patented its Micronite filter which contained crocidolite, promoting it as a healthy alternative to standard filters.
Other forms of asbestos
These three forms of asbestos may be less familiar, but still pose a significant danger to health if their fibres are inhaled. They weren’t used as prolifically in industry as crocidolite, amosite and chrysotile, but are still present in many insulating and fireproofing materials.
Tremolite (Calcium Magnesium Silicate Hydroxide) is part of the amphibole class of asbestos, and has needle-like fibres that are extremely difficult to expel from the body. Commonly a constituent part of other minerals including vermiculite, talc, and chrysotile asbestos, tremolite can occur in shades of green, grey, white or brown.
Tremolite was mined only in a few places globally, and in small amounts, and products containing the substance are not often seen in this country. It is thought to be as dangerous as other forms of asbestos, however, if handled incorrectly.
Where might you come across tremolite?
Although its use was not as widespread in industry as blue, white, and brown asbestos, tremolite’s insulating properties made it useful in some construction materials. It may be found in:
- Asbestos insulating board (AIB)
- Asbestos cement sheeting and pipes
- Casings for telecoms and electrical wiring
- Thermal insulation, such as lagging
- Fire doors
- Vermiculite products such as loft insulation, whitewashes and packaging materials
- Talc products, including ceramics and chalks
- Paint and sealant
Anthophyllite is a magnesium and iron silicate that is fibrous in nature, and also very brittle. It is generally brown in colour, but various other shades may be present, including green, grey and yellow.
As a member of the amphibole class, anthophyllite fibres are needle-like in appearance but unlike crocidolite and amosite, they have low tensile strength and for this reason did not have the same value to industry.
Anthophyllite can be found in various areas of America including Pennsylvania and Montana, and also in Asia and Northern Europe – Finland in particular.
How was anthophyllite used?
It can be found in the vermiculite products mentioned above and historically, also in cosmetic talcum powders. Uses include the manufacture of building materials due to its insulating and fireproofing properties. These include:
- Asbestos cement
- Composite flooring
- Roofing material
- Paints and sealants
Actinolite is similar in nature to tremolite, but less commonly used. Although having an identical crystal structure, actinolite contains more iron but less magnesium than tremolite. It was mined in several areas around the world, including Australia and North Caroline, USA.
Which products might contain actinolite?
This substance was generally included in insulation and fireproofing materials, along with other minerals, and is generally brown, grey or green in colour. Older residential and commercial buildings may still contain products manufactured with actinolite, as it provided a lightweight insulating solution in the building trade.
Its uses included:
- Concrete materials
- Sealants and paints
- Horticultural vermiculite
All three of these forms of asbestos have the potential to cause life-threatening disease if they are inhaled or ingested by the body. Asbestos awareness training covers all six forms of asbestos, so you’ll know where they might occur and what they look like.
Asbestos Mines of South Africa
South Africa has one of the highest rates of mesothelioma in the world, due to its extensive mining of amosite, crocidolite and chrysotile. It was the only country that mined all three main types of asbestos, with production at its highest during the 1960s and 1970s.
The use of heavy machinery including pneumatic drills, significantly increased the danger for South African workers who became seriously ill in large numbers. The health effects of working with asbestos were finally recognised in 2008, when legislation was introduced to prohibit the use, manufacture, import and export of asbestos and asbestos-containing materials in South Africa.
The Australian Blue Asbestos Company
The Australian town of Wittenoom is now described as a “ghost town” after more than a thousand residents, many of them miners, died from asbestos-related disease. After being the only Australian supplier of crocidolite, the town was shut down by the Government of Western Australia in 2007.
The name of Wittenoom has been removed from maps and road signs in an effort to deter visitors to this highly contaminated area, and the power grid was turned off in 2006. In 2016, only three residents remain.
Crocidolite fibres, once inhaled, are very difficult to expel. They set up life-threatening diseases and terminal cancers in later life – a fate experienced by many of the residents of Wittenoom.
Does asbestos always pose a danger?
If left undisturbed, asbestos is not considered a specific danger to health. It is only when attempts are made to remove it, or its fibres and dust are released into the air, that it becomes a health hazard.
Asbestos fibres, although very small, are also extremely strong. It is this combination that makes them so easy to inhale. They lodge within the lining of the lungs, potentially setting up fatal disease such as mesothelioma and other lung cancers.
Many people are unaware of the risks posed by asbestos – it is commonly thought that it was a historical problem, rather than a current one.
Who is at risk from the substance?
Anyone whose work could bring them into contact with asbestos is potentially at risk. This includes tradespeople such as plumbers, heating engineers and electricians, but also surveyors, architects and engineers.
Private individuals renovating their own properties could also be at risk, but because of the increased likelihood of tradespeople coming into contact with asbestos, they are the group most exposed to harm.
Taking a wider viewpoint, it is possible that anyone working within commercial or public buildings such as schools and hospitals, could also be unwittingly exposed to asbestos dust and fibres. The prevalence of asbestos-containing materials within the construction industry makes the threat to health extensive.
So where might asbestos be found within these buildings?
The likely locations of asbestos
Commercial and public buildings
The fire-retardant properties of asbestos mean that its pervasive presence within commercial and public premises could include central heating systems, fire blankets and clothing, interior fire doors, insulation boarding and ceiling/wall panels.
The list of potential uses within a non-residential building is very long, but here are just a few:
- Ceiling tiles
- Cement sheeting
- Roofing materials
- Sprayed coatings
- Vinyl floor tiles
Used in the manufacture of many household products, the locations where asbestos can be found in domestic building is also long. It includes, but is not limited to:
- Pipe and boiler insulation
- Wall partitions
- Floor and ceiling tiles
- Garage roofs
- Window putty
Now we’ve established where asbestos might be located, let’s see what harm exposure to the substance can cause.
Mesothelioma and other asbestos-related diseases
This is a rare and aggressive form of cancer caused by exposure to asbestos dust and fibres. Although there are three types of the disease, the most common form following exposure to asbestos is pleural mesothelioma. When asbestos dust and fibres are breathed in, they settle within the lining of the lungs, setting up the environment within the body that causes this untreatable type of cancer.
Although non-malignant and varying in severity, it is thought that asbestosis can be a precursor to mesothelioma. Asbestosis is a long-term illness that results in severe breathing problems due to scarring on the lungs, caused by asbestos fibres settling in the respiratory system.
Asbestos-related lung cancer
It can be difficult to attribute lung cancer purely to asbestos exposure, as the disease manifests in the same way as other types of lung cancer, such as that caused by smoking. Asbestos-related lung cancer generally begins between 20 and 30 years following exposure to the substance, but can progress considerably quicker if the sufferer is also a smoker.
How to stay safe if you encounter asbestos
The Health and Safety Executive has issued specific guidelines regarding the handling of asbestos. Any company found not to have followed these requirements faces prosecution, unlimited fines, and potentially a prison sentence for the individuals involved.
Anyone untrained in the safe removal of asbestos is not only risking their own health if they disturb it, but also the safety of those around them. Workers who unexpectedly encounter a substance they suspect could be asbestos should leave it undisturbed, making the assumption that it is in fact asbestos if there is any doubt.
A risk assessment should then be carried out, and if necessary, licensed contractors called in to deal with higher risk asbestos-containing materials such as sprayed coatings, insulation and lagging.
If a licensed contractor is not required, only those specifically trained in non-licensable work should carry out the removal process.
Whose duty is it to manage asbestos?
The Control of Asbestos Regulations state that the duty to manage asbestos lies with owners or occupiers of commercial buildings who are in charge of maintenance and repair. Landlords also have a duty to manage asbestos in ‘common’ areas such as lifts, staircases, boiler rooms, store rooms and outbuildings.
An asbestos survey should be carried out to identify where asbestos is located within the building. A risk register can then be used to record its presence, condition, and whereabouts, being updated regularly to provide a current view of the exposure risk.