Top 9 questions on asbestos, answered.
What is asbestos?
Why is asbestos dangerous?
Why is asbestos bad?
What is asbestos made of?
Where does asbestos come from?
Where does asbestos grow?
What is asbestos used for?
What is asbestos exposure?
Why was asbestos used?
In this article we will try and answer the commonly asked questions about asbestos such as what is asbestos, why is it dangerous, why was it used, how do you get exposed to asbestos, where does asbestos come from - does it grow or is it mined?
Let’s start with what is asbestos?:
Asbestos is not a mineral in itself. It is a collective term given to a group of silicate materials whose crystals occur in fibrous forms.
There are two structural forms of asbestos: serpentine and amphibole. Although chemically and mineralogically different, both exhibit high resistance to temperatures and high force.
Serpentine has physical characteristics of curvy, wavy, wool like fibres. It is easily bent or spiraled the only serpentine type of asbestos used was;
Chrysotile commonly known as ‘white asbestos’ and found in a multitude of products from asbestos cement roof sheets to brake linings.
Amphibole has physical characteristics of needle like shards (similar to fiberglass). It is resistant to being bent or curled. There are two types of amphibole asbestos;
Amosite commonly known as ‘brown asbestos’ wide range of product uses from ceiling and floor tiles to insulation boards.
Crocidolite commonly known as ‘blue asbestos’ not as useful as other forms of asbestos due to lower heat resistance but still found in many products such as asbestos cement, and water storage cisterns and tanks.
So why is asbestos dangerous?
The HSE website states that:
Asbestos kills around 5000 people each year, this is more than the number of people killed on the road with around 20 tradesmen dying each week as a result of past exposure.
So what causes these deaths and why is asbestos bad?
The distinctive fibrous mineral strands of asbestos can easily split into smaller and thinner fibres eventually becoming microscopic in size - commonly known as asbestos dust - if this ‘dust’ becomes airborne and is inhaled it lodges in the lungs and passes into the bloodstream and causes all manner of asbestos related diseases.
The most common chronic disease associated with asbestos is mesothelioma which is always fatal. Other diseases associated with exposure to asbestos fibres (dust) are:
Lung cancer (usually fatal)
Asbestosis (often fatal)
Pleural thickening ‘plaques’ (non fatal)
Studies have shown it may take less exposure to Amphibole fibres to cause mesothelioma than Serpentine - one reason why ‘blue’ and ‘brown’ asbestos are looked on as more harmful than ‘white’ asbestos.
It is important to note that it is only inhaling asbestos fibres that is harmful, so how does this ‘dust’ form and get inhaled?
What is asbestos exposure?
Asbestos was used in thousands of different products from textiles and plastics to cement.
Whilst all asbestos containing materials carry a risk from exposure to fibres this varies according to the physical characteristics of asbestos containing material (ACM).
ACM’s are split into two main groups;
Friable - this type are easily reduced to powder when dry. These release fibres more easily into the air and thus pose a more significant hazard to health. Friable ACM’s include spray coatings, thermal lagging and ceiling tiles.
Non-friable - this type has the asbestos firmly bound in the matrix of the material. If left undisturbed these materials are unlikely to release measurable amounts of asbestos fibres. Examples of these ACM’s are asbestos cement roof sheets (found on many garages) plastics such as vinyl floor tiles or plastic moulded toilet cisterns.
So, what is asbestos exposure? Simply put it is where inhalation of asbestos fibres has occurred.
This may happen when a tradesman disturbs and inhales the dust when entering a ceiling void that has asbestos containing ceiling tiles or when a non-friable product like an asbestos cement product is cut up with a mechanical saw releasing fibres that otherwise would not have been released.
Historically, exposure to asbestos also occurred during the mixing and application of certain ACM’s such as spray coatings, textured coatings (eg Artex) and pipe lagging materials.
Considering how harmful exposure to asbestos dust is, it leads onto another very pertinent question.
Why was asbestos used?
To answer this question we need to understand the properties of asbestos that make it so useful and in doing so we will also answer the questions;
‘What is asbestos made of?’
‘Where does asbestos come from?’
‘What is it used for?’
‘Does asbestos grow or form?’
Asbestos has been used for over 4,500 years. Pre-historic cooking pots have been found strengthened with asbestos fibres and bodies of embalmed pharaohs were wrapped in asbestos cloths.
The Greeks gave it the name ‘asbestos’ meaning undefiled by fire as it was fireproof - and this is a clue as to why asbestos is so useful.
The Romans however knew about its harmful side as they observed ‘sickness of the lungs’ of slaves that wove asbestos into cloth. Here is a second clue to asbestos usefulness - it is a mineral that can be woven into cloth, and that cloth is fireproof.
In the 1800’s as the industrial revolution unfolded asbestos was looked upon as a wonder mineral and it was incorporated into lots of materials because it gave them:
Heat resistant properties (a good insulation material and useful for braking systems).
Fire resistant (excellent in cement products and fibre boards for fire protection in buildings).
Electrical resistance (a good insulator for electrical appliances).
Sound absorbance (Hence it’s common use in acoustic sound insulation).
High tensile strength (resistant to stretching adding strength to cements and plastics).
In 1896, the first asbestos brake linings for new horseless carriages were made by Ferodo, a British company.
Three years later, in Germany, the first patent was issued for the manufacture of asbestos cement sheets.
High-pressure asbestos gaskets were turned out in 1900 by Klinger in Austria.
The first asbestos pipes were developed in Italy in 1913.
U.S. consumption of asbestos peaked in 1973 at 804,000 tons but the peak world demand was about 1977 with around 25 countries producing almost 4.8 million metric tons per year, and 85 countries producing thousands of asbestos products.
This was despite the dangers of asbestos being well known since 1924 when the death of a 33 year old woman who worked as a weaver with asbestos was directly linked to asbestos and the term asbestosis was defined as the cause of death.
This resulted in a parliamentary report being commissioned into the asbestos industry and it’s conclusions were ‘that the development of asbestosis was irrefutably linked to the prolonged inhalation of asbestos dust, and included the first health study of asbestos workers, which found that 66% of those employed for 20 years or more suffered from asbestosis’
However the wonder mineral continued to be mined at an ever increasing rate. So, the reason asbestos was used is for all the reasons above - it really was a wonder material for the industrial revolution and it was incorporated into a vast array of products.
Where though does asbestos come from? What actually is it? Does it grow? (like a stalactite or stalagmite)
Asbestos is a set of six naturally occurring silicate minerals that all have in common a thin fibrous crystal structure.
The six mineral types are:
Asbestos does not grow as such but during its formation it could be said to grow its crystal structure.
Asbestos is formed in the earth’s mantle when a hot magnesium rich rock such as Peridotite reacts with water - hydrates - and in doing so forms a range of hydrated magnesium silicates one form of which is commonly known as asbestos.
So asbestos is a crystal formation of magnesium silicate hydrate and it is mined with peak world production of 4.8 million tonnes a year and despite all it’s known dangers it is still mined today although current production is down to 1.1 million tonnes.