Asbestos – understanding the risks
Asbestos continues to cause untold damage in the construction industry. Ian Rippin, commercial director of the National Laboratory Service (NLS), explains what it is, what it does and how to test for its presence
WHEN asbestos is damaged fine fibres become airborne and can be inhaled which can penetrate the lung tissue and trigger an inflammatory reaction. The body registers the problem and white blood cells are sent to engulf and attack the fibres. However, the fibres usually destroy the blood cells, causing fibrosis – irreversible scarring of the lungs.
Popular in the late 1800s, during the time of the Industrial Revolution, asbestos was used routinely as insulation for steam pipes, turbines, boilers, kilns, ovens and other high-temperature products. Previous observations of the health risks were forgotten or ignored at that time.
The first diagnosis of asbestosis was made in 1924 following the death of a woman aged thirty-three, after twenty years of working with the material. As a result of the diagnosis, a study was commissioned on asbestos workers in England, revealing twenty-five percent suffered from an asbestos-related lung disease. Laws were passed in 1931 to increase ventilation and to make asbestosis a recognised work- related disease.
Over 3,000 people die each year from asbestos related diseases in the UK and it is estimated to treble by 2020. While use in the West has declined since 1970, shockingly, in Asia and Russia the use of asbestos based materials continues to rise. More asbestos is now used in China than was ever used in America at its peak.
The crystallised fibrous minerals mean that asbestos is a very strong, resistant component; properties that are very useful for building and insulating. It is safe to assume that most buildings that were constructed or refurbished between 1950’s and mid 1980’s are likely to contain some type of asbestos based material.
Asbestos use has been the subject of voluntary and formal bans since 1969, with blue asbestos (Crocidolite) stopped almost completely in 1970; the installation of sprayed asbestos coatings was banned in 1985; asbestos-containing decorative plasters was banned in 1992; and the installation of asbestos cement was prohibited in 1999.
White (Chrysotile), blue (Crocidolite) and brown (Amosite) asbestos, all deemed potentially dangerous, and are now banned in the UK. The type of asbestos present within a material cannot be determined by colour alone, laboratory testing is needed to accurately identify the different types of asbestos.
Testing for Asbestos
Different types of asbestos have different toxicities; Chrysotile is the least toxic form of asbestos, with Crocidolite being most toxic. Establishing the level of toxicity is vital for environmental consultants to assess the health risk or risk of pollution to the environment as a result of asbestos contaminants on site.
To test for asbestos, a laboratory will typically require a small sample of the material which is believed to contain this substance. As one of many hazardous materials analysed, the National Laboratory Service (NLS) of the Environment Agency caters for both the identification of asbestos types and fibre quantification in representative test samples of soils and sediments, dust particles, building materials and general waste products. Samples are initially examined by eye, followed by more detailed examination using a low power (8x to 40x) stereo microscope.
Fibres observed in the course of these examinations are categorised on the basis of morphology and certain physical properties. Each fibre type is sampled and these are mounted in a refractive index (RI) liquid to match the most likely asbestos type.
Following the use of polarised light microscopy (PLM) fibres are identified as one of six asbestos types (Chrysotile, Amosite, Crocidolite, Tremolite, Anthophyllite, Actinolite). If a quantitative analysis has been requested and the sample contains asbestos materials, visible fibres are removed during identification and the sample is weighed. This quantitative method has a detection limit of 0.01% by weight.
Ian Rippin is the Commercial Director of the National Laboratory Service (NLS). The NLS provides confidential and cost effective analysis to a range of commercial clients.
To find out more about NLS asbestos testing, visit <a href=”www.natlabs.co.uk”>www.natlabs.co.uk</a> or call the NLS Customer Service Team on 0113 237 2177.
(Source: http://www.builderandengineer.co.uk/feature/asbestos-%E2%80%93-understanding-risks Builder and Engineer online)