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It feels like we’ve been talking about personal monitoring a lot lately, and rightly so. It’s a critically important part of ensuring the safety of people working in asbestos management, and yet to date there has been a lack of official guidance on it.

However, since 2019 the Asbestos Network (formerly Asbestos Leadership Council) has been working on creating some. It’s my understanding that this summer is the targeted release date. It can’t come too soon, particularly given that some recent licence applicants have been hauled over the coals for supposed failings – which seems unfair when there’s no definitive guidance to go by.

I want to examine the new guidance based on the latest draft. I’ll lay out the main points of it, but I strongly suggest you also give the original a read, and provide your feedback through your trade organisation. You can find the ACAD draft guidance page here (you’ll need to be logged in). ARCA doesn’t seem to publish draft versions of AN minutes on its guidance page, but you will be able to provide feedback through comments.


The first very welcome news is that the guidance is broad. By this I mean it recognises that personal monitoring is a means to several ends. Rather than focusing just on the initial testing, the guidance examines why you are doing the testing, and how you use the results for the practical ‘ends’.

As it stands, the guidance starts with those ends, and what it says is pretty much straight out of existing documentation:

  1. Establish that the four-hour control limit is not liable to be exceeded (after all controls including respiratory protective equipment)
  2. Check the effectiveness of control measures to ensure worker exposure is reduced as low as is reasonably practicable
  3. Select or confirm that the RPE in use is capable of providing the appropriate degree of protection
  4. Ascertain whether the exposure is sporadic and low intensity, and that the short term (10-minute) limit has not been exceeded
  5. Support current and future risk assessments. This is an extension of the second bullet, i.e. if the controls were not as effective as you anticipated, re-check any improvements you make.
  6. Provide medical surveillance records

My understanding is that this part of the guidance might be trimmed further, with more emphasis placed on health records (largely the four-hour time-weighted average) and the effectiveness of controls. This interpretation is reinforced by the choice of tests currently selected from the Analysts’ Guide for further detail:

Specific short-duration activity (SSDA) Monitoring 

This is the workhorse test that you will use most of the time. It is used to test a specific activity (i.e. to satisfy goals two and five above). The guidance talks about the importance of really focusing on the individual task. To this end it stresses that it is no longer good enough to, for example, talk about removal of asbestos insulation board (AIB) – now you need to detail the fixing too. An example given is breaking out a single AIB panel, followed by fine cleaning. This should be viewed as two separate tasks, and either you should test them separately, or prioritise the high-risk element.

The guidance doesn’t yet state what parameters you should follow for this type of test (but it will in later drafts). As the purpose of the test is to examine an activity, you are allowed quite a bit of licence. The flow rate (how hard the pump is working) should be between two and four litres per minute, and the minimum volume tested should be 120 litres. These recommendations are very much intended to ensure you get a decent limit of quantification (see below).

Four-hour time-weighted average (4Hr TWA)

The second test that the guidance highlights is the dreaded 4Hr TWA – although hopefully these will be far less opaque if you’ve read my previous articles on the subject.

Not in the guidance yet is an explanation as to why on earth we should be doing these tests, beyond ‘it’s for the health records’ or ‘the HSE says so’. 

Here’s my understanding. If an employer causes an operative to be exposed to asbestos, we should be able to tell them accurately how much they have been exposed. If we all pick different rules for these tests, it will be a mass of confusing numbers that could be interpreted in a whole host of ways. If however, we all follow an official internationally recognised method, proven to give good results, we have more of a chance at telling the real story.

Back to the guidance. The first thing it makes clear is that these tests are less about the activity, and more about the person exposed. If an operative is building an enclosure in the morning and then removing asbestos in the afternoon – it is the afternoon’s work that you would want to test. If the operative is removing nailed AIB for two hours, and then fine cleaning for one hour before exiting the enclosure, we don’t need to worry too much about splitting the testing down to capture the different activities – but you definitely need to catch that initial peak exposure.

Compared to other parts of the document, this section seems to be in need of a lot more work. Hopefully it will use plain English to detail that we are looking at four hours of activity, but that you are allowed to make some assumptions. Crucially, the guidance needs to underline that it’s NOT a four-hour test – it’s a four-hour calculation.

To understand this, look again at the example above. The operative is exposed for a total of three hours, so you could therefore assume nil exposure for the rest to make it up to four hours. It’s also worth remembering that if you test for two hours, but the activity runs for four, you are allowed to extrapolate the result to give you figures for the full four hours.

Again, the test parameters are not detailed yet, but these would be a flow rate of one to two litres per minute, and a minimum volume of 240 litres. Meeting this volume is crucial, given that there’s some flexibility in the testing parameters.

Keen observers will note that there is some overlap here. If the standard test you commission is two litres per minute for two hours, this will give you the minimum volume you need to qualify for the 4Hr TWA and also the SSDA. It’s therefore an opportunity to greatly increase how many of these ‘tests’ you complete. Whether the guidance will explicitly spell this out is yet to be seen.

Confused? Read my deeper dive into the 4Hr TWA

Unpicking the language

The personal monitoring guidance will also unpick some of the arcane language used by the Health and Safety Executive (HSE) and analysts. In particular, it tries to explain the following:

Limit of quantification, calculated results and reported results

The limit of quantification (LoQ) is a calculated level of asbestos found, above which the analyst can be confident of the result. Below the LoQ, the counted fibres are so few and far between that some could have been missed. The guidance explains this, then goes on to tell you how to calculate the LoQ, which is probably too much detail for the purpose of the document.

Calculated result. This is effectively the analyst’s ‘workings out’. It is never the final answer, and should be taken with a grain of salt. The reason? It’s often below the LoQ, which we already know is the lower limit of confidence. You, as the user of the data, should always refer to the reported result.

Reported result. This is the analyst’s answer to the question – ‘what was the exposure?’ It will either be equal to or above the LoQ (i.e. the analyst has confidence in reporting it).

It might help to look at a couple of simple examples:

LoQ stated as 0.05

Calculated result 0.01

Reported result <0.05

As the analyst I can only be confident if the result is above 0.05. This is below that, so all I can be sure about is that it is less than my LoQ.

LoQ stated as 0.05

Calculated result 0.06

Reported result 0.06

I can only be confident if the result is above 0.05, and this is above that, so I am comfortable reporting 0.06.

Next, the guidance looks at what level of detail you need to record. The short answer is: ‘more’. The guidance recognises that historically, licensed asbestos-removal contractors made fairly simple records such as ‘AIB removal’, ‘pipe insulation removal’ etcetera. This is now considered insufficient for the obvious reason that removing nailed-on AIB is a very different job to screwed AIB, never mind glued AIB. The minimum parameters you should be detailing are now: activity, the nature of the asbestos-containing material (ACM), and the fixing used to install it.

Health Records

The final point I listed right at the beginning of this review was health surveillance records, and it does look like the guidance will give a very good steer on what this entails.

Outside of the asbestos industry, employers need to keep employee records for up to six years after the employee leaves the business. In our industry, however, employee health records have to be kept for a very long time – specifically, 40 years after the last entry, or until the employee would be (or would have been) aged 80: whichever is longest. For example, if you employ a 22-year-old for three months, you should keep their health records until they turn 80. If an employee retires at 55, you must keep their health records until they turn 95.

Health records are formed from the exposure records that we have been discussing up to this point, and in particular the 4Hr TWA data. In addition they include:

  1. Employee personal details
  2. The average duration of exposure in hours per week 
  3. A record of any asbestos work an employee did before their employment started
  4. Dates of medical examinations
  5. The system you used for ensuring medicals are planned and undertaken

These can all be from separate records or systems. Records one and three will come from your HR data. Four and five are more related to your personnel certificate management system.

The second one is a little more tricky. The approved code of practice (L143) requires the recording of exposure duration and fibre levels, but it doesn’t require these to be multiplied together to provide a measure of dose in fibre hours; that requirement was retired in 2006. What your system does need to do is give the individual worker a breakdown of their actual exposure against your company’s anticipated levels.

Summing up

It’s important to remember this remains draft guidance – and it could be some months off being issued formally. What’s more, the HSE is not in the market of giving you a specific solution. Instead, its guidance makes clear your duties and – if written well – should give you a steer as to what they mean in practice. The actual solution is up to you.

Say you implement an extensive system of Excel spreadsheets that you religiously maintain, and data-mine for the answer to different questions. As long as you already record all of the information that the new guidance demands – and your Excel skills for reports, charts and queries are up to the task – there will be little extra work here. 

For the rest of us, the presence of guidance brings a very real problem: when it is out, your performance can be measured against it.

Fortunately, I’m able to offer some reassuring news to the Assure360 community. All of our users are already covered, as the ‘new’ three-tiered approach (activity-ACM-fixing) has been in place since I created the system. Also, our comprehensive suite of reports provides all the required detail you’ll need for employee health records, 4Hr TWA calculations and much, much more.

If you’ve got concerns around the guidance and the changes you’ll need to make, or simply if you’re yet to see what Assure360 can do for you, why not contact us? We’d be delighted to give you a demo, and set up a free pilot of the system.

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