Disused buildings at former factories and industrial sites are often found to contain asbestos insulation, which could pose a health risk if disturbed. The discovery of the deadly fibres during pre-renovation or demolition surveys can instantly raise asbestos awareness among concerned local residents who already suspect that the materials may be present. It is another reminder that the legacy of Britain’s widespread use of asbestos as low-cost insulation in the last century can still present a health threat in the 21st.
It is thought that more than 50 per cent of all Britain’s residential development occurs on sites once occupied by asbestos works. The sites of former factories, foundries, mills and engineering workshops are often a potential health risk to both local area residents and building site/demolition workers from asbestos containing materials (ACMs) used in original building construction or later renovations. However, all types of public commercial buildings can contain ACMs.
In one recent example, an application to demolish former cattle market buildings in Bingley, Bradford, W.Yorkshire, has raised the concerns of the nearby community after asbestos was discovered in the building’s roofing sheets. The firm contracted to carry out the demolition confirms the presence of asbestos on the site, which has been unused since 1995, but also seek to reassure residents by saying that the majority is “very low risk” and “no risk” beyond the site perimeter.
100 per cent white chrysotile asbestos
During the peak years of use in the UK, around 170,000 tons of asbestos was annually imported from the 1940s until the late 1970s and early 80s. Asbestos fibres mixed with cement of between 10 to 15 per cent per cent or more was used to produce all types of insulation and fireproofing materials for the building and construction industry.
The weatherproof properties of asbestos cement meant it was widely used in the production of corrugated roof sheets, slates and soffits, sills, copings, chalkboards, fascias, infill panels, etc. Following the first ban on the most dangerous blue and brown asbestos types in the mid 1980s, builders could still be using their stock holding of white ‘chrysotile’ insulation and fireproof materials for at least another ten years.
A corrugated cement roof is probably the most common and identifiable form of asbestos, which many property owners and building firms are likely to encounter whenever renovation, removal or demolition work is being carried out. Often the inside of an asbestos cement roof will be lined with plasterboard or fibre-board panels where the paper lining is found to be made from 100 per cent white chrysotile asbestos. In some buildings it has been discovered that the lining panels were made from brown ‘amosite’ asbestos or with both amosite and blue ‘crocidolite’ asbestos.
A damaged, leaking or otherwise weakened roof will also affect the internal lining panels and cause the fibre dust particles to break off and disperse into the surrounding atmosphere. This might occur even when the asbestos materials are normally considered relatively safe because the fibres were originally factory bonded to the cement.
Commonly thought that bonded asbestos material poses no risk
In the method statement, submitted to Bradford Council, the demolition firm states that “bonded asbestos cement” is presumed to be present in the roofs and cladding. Hard bonded asbestos was the most commonly found form of asbestos used in flat corrugated or compressed asbestos-cement sheeting on garage roofs. It is commonly thought that bonded asbestos material poses no risk.
However, prolonged and severe conditions of extreme weather or temperatures can cause the integrity of the material encapsulation to break down, which could result in the release of asbestos fibre dust. An asbestos management review carried out in 2011 advised that there should be a reassessment of the potential risk posed by ‘bonded’ asbestos.
The dangers from asbestos roofing could be more widespread than might be imagined. The Land Registry state that more than half (55 per cent) of all industrial / commercial properties in the UK contain a chrysotile asbestos cement roof. Nearly every report of illegal fly-tipping can also involve quantities of broken up asbestos corrugated roofing sheets or wall board.
The Health & Safety Executive (HSE) estimate that around 1.8 million people across Britain are still in danger of exposure to asbestos. In July 2016, HSE published their latest “Statistics on Fatal Injuries in the Workplace in Great Britain”, which indicates that 2,500 cases of mesothelioma are now diagnosed every year.