Mask or management

Feature image

Charles Pickles on why scanning electron microscopy is so crucial to the effective management of asbestos

The use of asbestos in construction material was banned in 1999 and large quantities have been removed from buildings. Government policy considers that asbestos which remains in good condition, and is unlikely to be damaged or disturbed, is not a significant risk to health, providing it is properly managed. As a result, there are still many properties where the decision has been made to leave it in situ and manage its presence.

For those responsible for maintaining buildings where asbestos is known to be present, the crucial question is how can it be dealt with safely?

Who is responsible?

Strict Health and Safety Executive responsibilities mean there should no longer be any excuse for anyone being exposed to potentially dangerous levels of airborne asbestos fibres. Specifically, regulation 4.8 of the Control of Asbestos Regulations 2012 says that a determination of the risk from any asbestos known to be present is made.

The regulation is also designed to ensure that anyone who carries out any work in non-domestic premises, and any occupants of the premises, are not exposed to asbestos from asbestos-containing materials (ACMs) which may be present.

Responsibility falls to the duty holder, who has clear accountability for the maintenance or repair of the premises. The duty holder is required to assess and manage risks from asbestos and must ensure that anyone who is likely to work on or disturb asbestos is given information about its location and condition.

Rigorous systems of asbestos management require regular inspections and checks on the condition of ACMs, and should include details of any precautionary or safeguarding measures needed. As part of this requirement, an assessment of the risk associated with each identified occurrence of asbestos is required.

Effective risk management

Modern air monitoring and analytical techniques have the capability to detect much lower concentrations of any asbestos fibres that may be present. This means it is now far easier to conduct regular monitoring of workplace air samples rather than simply monitoring conditions after the completion of building repairs or asbestos removal work.

In particular, a formal programme of reassurance air monitoring using powerful scanning electron microscopy (SEM) can more effectively measure occupational exposure concentrations for asbestos fibres compared to other laboratory techniques.

SEM enables asbestos in air to be quantified to very low levels, typically achieving lower limits of detection to 0.0005 fibres/cm3 and below, compared to the 0.01 fibres/cm3 capability of standard phase contrast microscopy (PCM). SEM can also distinguish between different asbestos fibre types and other non-organic fibres.

Current analysis using standard PCM has a limit of detection that is wholly unsuitable for risk assessment in an occupied environment and is only really valid for asbestos removal monitoring. SEM’s ability to more accurately determine whether asbestos fibres are present means it can better identify the level of any risk present and what remedial actions are required.

Air monitoring using SEM enables actual and direct asbestos risk measurements to be made in specific building locations. This can be used to prioritise risk and target spending on remedial works to provide reassurance that those present in the building are not being exposed to harmful fibre levels.

A future defence

This is particularly important in bolstering any defence against a  future legal claim, as the duty holder will need to demonstrate that the best available ‘practicable’ technique was used to enable a suitable and sufficient risk assessment to be made.

With asbestos fibres, there is usually a time interval of decades after any exposure before the onset of disease. For the person responsible in law for the provision of a safe working environment, the prospects of civil litigation at some time in the future from someone who subsequently develops mesothelioma should not be overlooked.

As a result, if potential liabilities are to be defended, it will often be necessary to demonstrate that airborne asbestos concentrations do or did not significantly exceed background levels. To be relevant, the sampling needs to coincide with suitable and representative site activities and conditions – however, the impact of false positives associated with the inclusion in samples of non-asbestos fibres can be considerable.

In such circumstances, PCM will give only a total fibre concentration, rather than an asbestos fibre concentration, so the ability of SEM to discriminate between asbestos
and non-asbestos fibres is vital.

Workplace air sampling and analysis utilising SEM can ratify the effectiveness of existing asbestos management techniques and provide vital reassurance that those present are not being exposed to potentially harmful asbestos fibre levels.


About the author

Charles Pickles
Chief Technology Officer at Lucion Services
0345 5040 303 Email