There was a tragic story in one of the nationals last month of a woman in Plymouth who had died from lung cancer as a result of exposure to asbestos. The fatal contact was reported to have came 40 years earlier when the woman would hug her grandfather, a docker, whose coat was often covered in fibrous dust from his work. Her death acted as a vivid reminder of a problem that many people would assume had been consigned to the past.
The truth is that asbestos-related diseases still claim the lives of 4,000 people annually in the UK. Many of these victims were exposed in the post-war years, when the material was imported in huge volumes and used in building construction. Indeed, the death spike from asbestos is expected to peak around 2015, after which date it will gradually start to decline. But, while the importation and use of asbestos is now banned, it remains hidden away in the walls, roofs and pipes of many buildings. That means future generations still face a worrying risk of asbestos exposure.
“Asbestos is a hidden killer,” says Sarah Mallagh, manager of the asbestos policy team at the Health and Safety Executive. “It’s still a huge problem and we are working hard to raise awareness. We recently carried out research which showed that, while most people know that asbestos is harmful to health, a significant percentage of those questioned believed it was a historical problem. That’s not the case. Potentially, asbestos is contained in any building constructed from the middle to the turn of the 20th century. So tradespeople are still likely to come across it. If they are unaware that it is there, they will be oblivious to the fact that they could be cutting or drilling into it.”
Asbestos is the generic term for a wide range of minerals that crystallise to form long thin fibres and fibre bundles. Most common is the serpentine group, which includes chrysotile (white asbestos). A second asbestos group known as the amphiboles includes crocidolite (blue asbestos) and amosite (brown asbestos). The fibres have high tensile strength, and chemical, electrical and heat resistance – properties that made asbestos useful as a construction and insulation material.
Asbestos can only pose a risk to health if its fibres become airborne and are then inhaled. Therefore, most asbestos materials pose little risk unless they are disturbed in some way that allows the fibres to be released. Inhalation of fibres can lead to diseases such as lung cancer, mesothelioma (a cancer of the linings of the lungs – the pleura, or lower digestive tract – the peritoneum) and asbestosis (a chronic fibrosis of the lungs).
“Health issues occur when there have been cumulative doses,” says Mallagh. “The more regularly exposed you are, the more likely you are to be affected. One-off exposure is unlikely to cause any serious illness. But cumulative doses are extremely dangerous.”
Many cases of diseases occurring now are a result of exposure in industries that used asbestos in the past. However, the fact that asbestos was also installed in many buildings means that a wider range of people still have the potential to be exposed – particularly building workers. For this reason the Control of Asbestos Regulations 2006 brought together three previous sets of regulations covering the prohibition of asbestos, the control of asbestos at work and asbestos licensing, together with a “duty to manage asbestos” for those responsible for non-domestic premises.
“Exposure does still happen because asbestos is so pervasive,” says Mallagh. “There can be big fines for companies who fail to comply with the relevant regulations.
”That was the case last September when support services firm Interserve (Defence) was fined £33,000 and ordered to pay costs of £17,936 after an asbestos survey undertaken in the boiler room at a Ministry of Defence base in Bicester in 2005 found asbestos contamination and recommended that access to the room should be restricted until it was removed. Interserve was found to have failed to follow the advice of the survey and so workers were left at risk of exposure to deadly asbestos fibres for over a year.
For those responsible for an industrial unit or building there is a legal requirement called a “duty to manage asbestos”. That means there is a need to conduct an asbestos risk assessment and produce an asbestos management plan. That involves finding out where asbestos might be and deciding what action to take. Asbestos is only dangerous when disturbed – therefore the HSE advises firms to avoid unnecessary removal.
“The ‘duty to manage’ does not require asbestos removal,” says Mallagh. “If the asbestos is in good condition, and is unlikely to get damaged, then it should be left in place and monitored. However, if it is in poor condition, or it is likely to degrade and release fibres, then it should be encapsulated or removed.”
In some cases removal is the only course of action. For instance, the Chapelcross Magnox nuclear power plant in Dumfries and Galloway has 16 enormous heat exchangers, each of which is clad in asbestos. A decommissioning programme at the site means that material must be removed and disposed of. The scale of the £30 million, six-year project is truly immense: 3,300 tonnes of asbestos will be stripped away, making it currently the biggest asbestos removal project in Europe.
Dave Wilson, site director at Chapelcross, explains the need for removal: “The plant was built in the 1950s and key to its efficient operation was minimising heat loss. Asbestos was used to clad all major parts of the heat exchangers at thicknesses of between 100mm and 150mm.
“Magnox is an older site, and in those days the heat exchangers were built externally, so they were exposed to the elements. Over the years the asbestos was painted and maintained. Indeed, when the site was generating electricity, the heat produced helped to drive out moisture from the asbestos and keep it in good condition. However, since electricity generation has ceased, water has permeated the asbestos and it has become absorbed. Chapelcross is on the wet, windy west coast of Scotland. And those conditions caused the fall of some asbestos.”
Even before any asbestos could be stripped, a huge containment structure was built around each heat exchanger, providing a controlled environment within which to carry out the physically demanding work. Powerclad sheeting was used to protect the asbestos from the environment and provide some element of containment if any of the material fell to the ground. That work cost £3 million and took two years to complete.
The stripping process takes place within an airtight structure that is built within the contained housing. This work is undertaken by Kitsons, part of the Silverdell Group, which is one of the UK’s biggest licensed asbestos removal companies. At one end of the airtight structure is an airlock, and at the other is a negative pressure unit which is used to remove any residual fibres via a Hepa filter while stripping is being carried out. But before any work is carried out, a smoke test is undertaken to ensure that the structure is airtight.
Once this is done, the asbestos is injected with a substance that helps bind it, so that it comes off in lumps rather than fibres. The job is done by workers kitted out in full respiratory equipment. First, a bulk strip from top to bottom of the heat exchanger is carried out, with as much as 150 tonnes of asbestos being removed within 10 days. “It’s hard, manual work,” says Wilson. “The guys are up on scaffolding in suits hauling it off, cutting it up and bagging it.”
Then a fine clean is carried out. Every part of the heat exchanger is taken back to bare metal using manual methods and a dustless grit blasting machine known as a quill falcon. This is a slow process, taking up to six weeks, as it often involves cleaning around hard-to-get-at fittings such as welds and pipes. Then the structure is washed down, where the odd fibres are picked up, and there is a visual inspection by an independent firm. If the work is passed, a stage-two clearance is then issued and the job progresses.
Then air samples are run for a set number of hours, with the filter papers taken away for assessment. If the fibres on the filters are below acceptable levels, then a stage-three clearance is awarded. The containment tenting is then removed, and a final check is carried out, before the structure can be deemed to be asbestos free. “It is a manual process, but it is still forensically done and it is very precise. It is carried out to very tightly controlled standards,” says Wilson.
So far asbestos has been removed from eight heat exchangers, with eight more to go. The project will be finished by September 2012. Wilson is delighted with the way the project has gone so far, and has nothing but praise for the professionalism of the contractor Kitsons.
He says: “The project involves 550,000 scaffolding tubes, 200,000 scaffolding fittings, 24,000 scaffolding boards, 280 ladders and 70 people on site. And so far there have been 250,000 man hours on the project without one accident. Kitsons has been exemplary in its work.”
The work at Chapelcross represents one of the more successful removal projects. But the HSE admits that there needs to be greater awareness of asbestos issues to ensure that other buildings and facilities with asbestos legacies are dealt with in a similarly professional manner. There are a total of 600 licensed asbestos removal companies in the UK, and each of them is regularly checked by the HSE for competence. “The UK is proactive in this area,” says Mallagh of the HSE. “For example, not all countries have a licensing regime or have specific duty-to-manage regulations that put the onus on those in control of the building.
“There is a legacy issue in the UK, because asbestos has a long lifespan. So I would say to companies that they need to be alert. And if they think they have a problem, then take proactive steps and put a proper course of action in place.”
Death toll has yet to reach its peak
As asbestos fibres accumulate in the lungs, several diseases may occur. Principally there are two kinds of cancer:
» Mesothelioma is a cancer of the pleural and peritoneal lining and is considered to be almost exclusively related to exposure to asbestos. It is almost always fatal, with those affected usually dying within one or two years of diagnosis. Mesothelioma has a long latency period that is typically between 30 and 40 years.
» Lung cancer is a malignant tumour of the bronchi – the tubes carrying air to and from the lungs. The tumour grows through surrounding tissue, invading and often obstructing air passages. The latency period is typically at least 20 years.
The annual number of mesothelioma deaths has increased considerably over the period for which statistics are available, reaching 2,249 in 2008, compared with 153 in 1968. The expected number of deaths is predicted to increase to a peak in 2016.
Lung cancer deaths caused by asbestos are clinically indistinguishable from those caused by other agents such as tobacco smoke. This means the number of cases can only be estimated. Recent research estimated the ratio of asbestos-related lung cancer deaths to mesotheliomas by developing a model for lung cancer mortality within the population in terms of asbestos exposure and smoking habit. This suggests a ratio of 0.7 to 1 – fewer lung cancers than mesotheliomas.
