As an analyst with more than 20 years’ experience, I can count on one hand the number of occasions I have been asked by either a client or a licensed asbestos removal contractor (LARC) to undertake leak testing. Perhaps I am the exception, but my experience suggests that leak testing has become far less common than it should be.

The guidance is particularly timely given the Health and Safety Executive’s (HSE) recent announcement of changes to the Control of Asbestos Regulations 2012 (CAR 2012), intended to strengthen independence and impartiality within the four-stage clearance process.

Both developments have a common objective: ensuring that asbestos control measures are effective and independently verified where necessary. But will the new guidance deliver meaningful change or be just another box on the RAMS?

Why was new guidance necessary?

Regulation 16 of CAR 2012 requires employers to prevent, or where this is not reasonably practicable, reduce to the lowest level reasonably practicable, the spread of asbestos.  Paragraph 416 of the Approved Code of Practice (L143) specifically identifies the need for air monitoring to measure background fibre levels outside enclosures, particularly where work takes place within occupied premises.

Yet leak testing has become increasingly uncommon. The guidance identifies several reasons: additional analytical costs, difficulties with analyst availability, historically low test results and growing confidence in the effectiveness of larger negative-pressure units.

There is also a commercial reality. A contractor routinely including leak testing in its quotations may be at a disadvantage against competitors who do not. When clients are comparing tenders, price often wins over quality. If a service is perceived to offer little obvious benefit and comes at an additional cost, it is easily removed.

This is precisely the behaviour the new guidance seeks to challenge. Decisions about leak testing should no longer be based on custom, convenience or cost alone. They must be supported by a documented risk assessment, with responsibility resting with a named individual acting for the LARC.

A risk-based approach – or an excuse not to test?

Importantly, the guidance does not demand leak testing on every licensed removal project. Instead, it requires LARCs to assess the risks and determine whether testing is necessary.

Considerations include building occupancy, the potential consequences of enclosure failure, interconnected ventilation systems and service penetrations, sensitive areas, anticipated fibre concentrations and the removal techniques being used.

This is sensible. The risks associated with removing intact asbestos-containing materials are clearly different from those involved in removing sprayed coatings, lagging or asbestos insulation board where significant breakage may occur. Similarly, a potential release into an unoccupied plant room is not equivalent to contamination of a hospital ward, school or care facility.

However, the effectiveness of this approach depends entirely on the quality of the risk assessment and the competence of the person undertaking it.

There is a danger that risk assessment becomes a mechanism for justifying the omission of testing rather than improving decisions about when it is needed. Recording a decision does not automatically make it the right decision.

Where testing is considered unnecessary, the justification should be clearly documented within the Plan of Work/RAMS. Poor or inadequate reasoning should be open to scrutiny, including during site visits and licensing assessments.

Empty buildings are not always an option

Reducing the number of people potentially exposed during removal is an obvious way to minimise the consequences of containment failure. It also recognises an important limitation of monitoring: a test may identify a release, but it cannot guarantee that nobody has already been exposed.

Even buildings considered unoccupied can present challenges. Cleaners, security staff, maintenance personnel, delivery drivers and other contractors may still enter areas assumed to be vacant.

Furthermore, complete evacuation is not always practical. Hospitals, schools, residential buildings and commercial premises may need to remain operational during asbestos removal. In these circumstances, leak testing becomes particularly important.

Clients and principal contractors must therefore take greater responsibility for project planning rather than leaving these decisions entirely to the LARC.

Negative pressure does not guarantee containment

Perhaps the most important technical message in the guidance is that maintaining negative pressure does not, by itself, demonstrate that an enclosure is preventing asbestos fibres from escaping.

Negative-pressure units, airflow and pressure monitoring, flap deflection checks and smoke testing are all valuable tools. However, none directly measures airborne asbestos fibres outside the enclosure.

The guidance highlights the possibility of a defective HEPA filter allowing fibres to escape without producing a significant change in pressure. Similarly, waste removal, personnel movements and alterations to an enclosure can create opportunities for contaminated air to escape despite negative pressure being maintained.

Leak testing provides a different and essential form of assurance. It measures airborne fibre concentrations outside the enclosure and can identify failures that other monitoring arrangements may miss.

Previous satisfactory results in similar projects should never become a reason to abandon leak testing.  Fibre concentrations can change, and every removal project presents its own risks.

Independence: a welcome change, but is it enough?

The HSE’s amendments to Regulation 20 of CAR 2012 provide an important additional dimension.

The changes will require the client, rather than the LARC, to appoint the UKAS-accredited laboratory undertaking four-stage clearance air testing. The new arrangements are intended to remove potential conflicts of interest and strengthen confidence in the independence of analytical services, with implementation expected from November 2027.

The new leak-testing guidance places responsibility on the LARC to decide whether testing is necessary but they are no longer responsible for paying for it.  This could actually see an increase in the amount of leak testing being carried out as they will no longer be at a commercial disadvantage for recommending it.  However, it could also lead to tension as the organisation undertaking the removal work is also deciding whether independent verification of its containment arrangements is required.

Involving a suitably qualified analyst in developing the monitoring strategy, alongside meaningful Client engagement, would help ensure that decisions are based on technical considerations rather than commercial convenience.

There is also an opportunity for the HSE to reinforce these principles when it next reviews L143 and HSG248.

Will the guidance actually change behaviour?

The guidance is concise, practical and addresses many of the industry’s established arguments against routine leak testing.  It provides a framework for challenging contractors who omit testing simply because it has never formed part of their normal working practices.

However, three significant challenges remain:

First, different contractors and contract managers may interpret identical circumstances differently. Without consistent application and scrutiny, a risk-based approach could produce inconsistent standards.

Second, commercial pressures have not disappeared. Unless clients understand their responsibilities and are prepared to fund appropriate monitoring, contractors will continue to face incentives to minimise testing.

Finally, the guidance needs active support from the HSE, licensing authorities and industry organisations. Inspections and licensing assessments should examine not simply whether leak testing took place, but whether decisions not to test were properly justified.

Ultimately, this is about changing hearts and minds. The industry has operated in a particular way for many years, and changing established behaviours will not happen overnight.

The objective should not simply be to increase the number of leak tests or ensure every building is empty during asbestos removal. It should be to establish a genuine partnership between the client, LARC and analyst, with each understanding their responsibilities and working together to prevent the spread of asbestos fibres.

The new guidance provides an important opportunity to achieve that. But guidance alone will not deliver change. Competence, independence, accountability and a willingness to invest in appropriate monitoring are essential.

If we are serious about preventing asbestos exposure, leak testing must be treated as an essential part of managing risk, not an optional extra to be removed when the quotation becomes too expensive.