Assure 360

What is the point of the four-stage clearance (4SC)? It’s a serious question. If the point of removing asbestos-containing materials (ACMs) is to make an area safe for the people who want to live or work there, then the 4SC isn’t just boxes to tick on a form – it’s the final, critical part of ensuring that the area is actually now safe.

As a legally mandated check, the 4SC is there as an independently executed analysis of the licensed asbestos-removal contractor’s (LARC’s) removal and cleaning processes. If we can’t trust it to work, we can’t have faith in any of our asbestos-removal framework.

The Health and Safety Executive (HSE) knows this only too well, which is why in 2014/15 it conducted a thorough study into analytical practice in the industry. Finally, the report is out – although the November 2018 publication is still marked as a draft. What does it say, what can we conclude, and what comes next? Here’s my analysis.

The four-stage clearance explained

First, some background. The 4SC is a legal requirement after any licensed asbestos removal work. It must be conducted independently, by a qualified analyst working either for the LARC (contractually, rather than directly), or the client themselves. It’s a test of the enclosed area within which controlled asbestos-removal has taken place and, obviously, it comprises four elements:

  1. Scope – has the job been completed and is the site essentially clean and tidy?
  2. A thorough visual inspection inside the enclosure
  3. An air test using phase-contrast microscopy (PCM)
  4. A final assessment after the enclosure has come down

The second stage is widely accepted as the most important part: if there is no visible asbestos (including dust of any kind) then the air test is likely to pass.

Previous studies and anecdotal evidence indicate that audited 4SCs fail more asbestos-removal work than unchecked ones, strongly suggesting that a watched analyst is more diligent. While that may only be human nature, our primary interest here is in establishing a reliable quality standard. With something this safety critical, training and procedures need to work together to ensure consistent standards across all 4SCs.

What did the HSE investigate?

The HSE’s investigation sought to explore if and where the current systems were failing, and establish how to rectify any problems. Its first step was high-level information gathering in the form of a questionnaire sent to all (as of 2013) asbestos labs. This was followed up by 22 head office visits, and 20 site inspections during 4SCs. The very first thing this tells us is that if not actually volunteers, all of the participants had at least some warning before they got involved.

In all, approximately 70% of analyst organisations gave information, and 15% of organisations received a head office and inspection visit. When in 2017 the HSE’s Dr Martin Gibson revealed some of the early findings, he made it clear that avoiding the questionnaire did not reduce the chance of getting a visit – quite the reverse, I would hope!

The HSE reports some raw stats:

  • There are around 30 large analyst organisations employing over 40 individual analysts
  • Forty five organisations employ 30-40 analysts
  • Thirty one organisations carried out 66% of all 4SCs during 2013
  • Nineteen organisations performed fewer than 100 4SCs between them in the year
  • Two conducted fewer than 10 clearances that year

Four-stage clearance failures

Three-quarters (75%) of the companies reported that less than 20% of all 4SCs were not up to the required standard at the first time of asking. Just to clarify, that’s a LARC’s cleanup work being found inadequate in less than one in five cases. That sounds promising, but the extremes of the scale were astonishing. Two percent of labs stated that they failed over 80% of site enclosures the first time round, whereas about 10% of analysts said that they never failed clearances!

That’s a big spread, suggesting a big variation in standards, and the HSE is keen to address it. The report insists that analysts should provide photographic evidence in clearance certificates to back up their decisions. It’s a move that has long been telegraphed – and is becoming increasingly common practice.

Nearly all laboratories reported that some remedial work was always required to allow enclosures to pass at stage two (the critical visual check). Often, where this extra cleaning was ‘minor’, it was done by the analyst. But what is ‘minor’? One analyst reported cleaning, without the LARC, for over an hour.

THe HSE makes it clear – cleaning an enclosure is licensed work, and if an analyst does it they’re breaking the law.

Let’s not mince words here: the enclosure should be clean before the analyst gets to it. Not only should the operatives have cleaned it thoroughly, but the supervisor should have done their own visual inspection – just as diligently as the analyst is about to do. If it’s not clean, the LARC didn’t clean it properly, and every time this happens it should result in a failure. Only then can work standards, and those of the individual supervisor, be tracked and rectified.

A focus on supervision

The competency, or otherwise, of supervision was questioned by several of the labs, with some questioning whether supervisors had even completed their own pre-analysis visual inspection. Looking at the situation from the other side, I know that top-quality, diligent supervisors are recognised within the industry as the gold they are.

To address these process failures, the HSE is introducing two new measures:

  • A handover form (HF), which must be completed and signed by the supervisor stating how long a visual they have conducted, and without which the analyst should not even start
  • Any re-cleaning during the 4SC must be undertaken by the LARC, and limited to 10 minutes. When exceeded, the analyst should leave the enclosure and formally issue a failure certificate

Together these will constitute valuable management tools for LARCs who seek to monitor and improve their processes. By tracking how many HFs are issued before an area passes the 4SC, the LARC can assess the effectiveness of its own cleaning and supervision. The percentage of enclosures passed first time could even become a target for supervisors. At the same time, analysts need to be able to back up their decisions – hence the call for photographic evidence in clearance certificates.

At Assure360, we’re keen to support these processes. In Assure360 Paperless, all enclosures are formally passed (signed on the tablet) by the supervisor, and this data is emailed to management and the analyst. Once the analyst has completed their 4SC, they also sign for a pass or a fail. Because we deal in data, not ‘smart’ forms, the team can track progress in real-time, and we can report on trends at the touch of a button.

Understanding decontamination

The HSE found that the understanding of personal protective equipment (PPE), primary and full decontamination was approximate. Some analysts wore normal clothing under their coveralls, and decontamination was often found to be poor, with analysts having no written procedures or training on the subject.

The report stresses that detailed written procedures must be in place for all analytical companies. These should insist that domestic clothing must not be worn inside enclosures, and they should include clear decontamination instructions – explaining when full and preliminary decontamination procedures are appropriate. They should also be followed by practical training on decontamination procedures.


What does the HSE think is suitable in this area? Read the draft report on the ACAD website, or read my Asbestos Analysts’ Guide white paper.

How’s my quality control?

The HSE didn’t generally find fault with quality control, and found that in some cases QC systems were highly sophisticated. However, there were multiple flaws in the work in practice. The HSE noted incidents including:

  • Ignoring the airlock and the initial areas of the enclosure and starting directly at the far end
  • Forgetting to bring a brush (for those unfamiliar with the air test, it is critical that analysts brush the area immediately beforehand to maximise surface disturbance)
  • Turning up unshaven (facial hair can reduce the effectiveness of respiratory protective equipment (RPE))
  • Overalls insufficient for the job

In some cases, the HSE’s observations led to enforcement action.

Air testing procedures also showed some poor practice – predominately where analysts rushed the counting of fibres, potentially leading to under-recording of asbestos. The HSE observed this on site, but also by studying 4SC certificates after the fact.

While some of these failings could be connected to the pressures to just get the job done, to my mind the trend reveals flaws in the auditing and implementation of the QC process. If these failings happened literally in front of HSE inspectors, then they’re likely to be normal behaviour that’s been missed or ignored by the analytical companies’ own audits.

In all, by my reading of the report there seemed to be significant questions in about a fifth of site inspections. The HSE has called for a strengthening of the processes including that:

  • around 5% of all 4SCs are audited/re-inspected
  • every analyst should be audited/re-inspected at least four times a year
  • auditing of stages two and four should be performed immediately after the analyst completes them
  • at least 5% of 4SC certificates should receive a desktop review

Personal Sampling

The HSE found the practice of personal sampling to be very poor – a personal bugbear of mine. Tests were predominantly run for only 10-30 minutes and included very limited information on what the operative was doing at the time. Together this leads to such small sample sizes that the reported results are high, yet provides no information to understand the result. In short, it’s near useless. Some analysts stated that licensed contractors were only willing to pay for the minimum of testing, but my experience (backed up by the report) is that LARCs don’t know what to ask for.

The Analysts’ Guide, when we finally get it, will help massively in this area, but in the meantime you can read my white paper on what’s in the draft version.

In contrast, the HSE judged background monitoring to be good, with accurate counting of fibres, plus floor plans and contextual information that illustrated clearly what was going on.

But here’s the issue: the skill set for both of these areas is fundamentally identical, and yet one was found to be very poor and the other excellent. This reveals a level of ignorance that still amazes me, and which isn’t restricted to analysts and LARCs. I have been in licence assessments where an HSE inspector has stated unequivocally that the a flow rate of one litre per minute is critical, and that exceeded this will invalidate the test. Wrong, but too many people believe that the rate is set according to how lungs work.

Tracy Boyle (ex-president of the British Occupational Hygiene Society) pinned Martin Gibson down on this at November’s FAAM conference. Essentially, the higher the flow rate the better. The bigger the volume of air tested, the lower the limit of quantification you can establish. These are the most important factors, and thankfully we will get clarity on them with the new analysts’ guide.

Who’s the boss?

Finally, the HSE also flagged up concerns about potential overwork and conflicts of interest within the 4SC system. Compared to when I started my career, 25-odd years ago, there seem to be fewer analytical companies working directly for the LARC. Similarly the days of multiple clearances per day are also reducing, though 30% of analysts still reported completing two 4SCs per day. While three or more 4SCs in a day was very rare, four organisations admitted that it happened on more than 20 days per year.

The HSE acknowledges that by working directly for the client, rather than the LARC, analysts will avoid conflict-of-interest problems. Its report also suggests a contractual clause specifying who pays for remedial work and retesting when an enclosure fails the 4SC, removing any pressure from the analyst on site. Whether the client is the building owner or the LARC, though, poor cleaning should mean the LARC pays.

Cold starting

A number of companies commented that coming to an asbestos-removal job ‘cold’ interfered enormously with their ability to make a positive impact on the project. The HSE underlined the legal duty on LARCs and their clients to cooperate with the analyst, and the report recommends that the analyst be involved from the earliest stages.

Ideally, analysts would undertake a pre-removal scoping visit to feed into the LARC’s method statement, but alternatively they’d at least receive a copy of the method ahead of time so that they don’t go blind into the job.

The report’s final recommendation is that the HSE repeats the whole exercise after it publishes the final version of the new analysts’ guide. I’ve got my fingers crossed that might finally happen this summer. In the meantime it’s worth restating that I’ve based this summary on the draft version of the HSE’s analyst report, dated November 2018. I’m given to understand that it’s essentially final, subject to a spell check.

If it helps, I didn’t find any typos.


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"At our recent license renewal, the HSE inspectors were amazed by the power of the system and could not believe everyone was not using it."
Ken Johnson, Managing Director, Delta Services