HSE guidance HSG248 Asbestos: The Analysts’ Guide Revised
The last time the HSE asbestos guidance was updated was in 2015. Six years later, the long-awaited revision is finally here - HSG248 Asbestos: The Analysts’ Guide 2021 - and is available on the HSE website.
This update to HSG 248 takes into account findings from Health and Safety Executive (HSE) interventions and developments in analytical procedures and methodology. As such this second edition is now the authoritative source of asbestos analysis methods in the UK.
Further improvements include clarification on technical and personal safety issues, especially in relation to asbestos sampling procedures and 4-stage clearances. Additionally, new information regarding asbestos in soil analysis methods is included in this revised edition.
Overall the guidance is designed to help asbestos analysts to comply with their legal obligations. However, it may also be useful for asbestos consultants, occupational hygienists, safety professionals, asbestos removal contractors, building owners and facilities managers.
4-Stage clearances
Before we take a look at what the revised edition has to say about clearances, let’s take a quick look at what the process involves.
What is a 4-stage clearance?
A 4-stage clearance procedure follows the removal of asbestos materials. The aim of clearances is to ensure the area is safe for re-occupation by members of the public.
The four stages of clearance are:
- Preliminary check of site condition - including where the asbestos containing material (ACM) was removed from, if any materials were to remain in situ and what the materials were removed were.
- Thorough visual inspection inside the enclosure area - including checks for the completeness of the removal of dust from all surfaces and the presence of any visible asbestos dust or fibres left inside the work area.
- Air monitoring - asbestos air sampling is carried out once the analyst is satisfied that there is no visible dust remaining. Dust disturbance is carried out to simulate re-occupation of the work area.
- Final assessment post-enclosure area dismantling - this stage is a final visual check for asbestos debris remaining after the enclosure has been removed from the work area. Examples include dust that may have fallen off the enclosure or sheeting as it was removed or fibres and dust that were missed during the cleaning process.
What the revised HSG248 has to say about 4-stage clearances
HSE’s Analyst Inspection Programme highlighted a number of issues surrounding 4-stage clearances, particularly time pressure and resources.
Many issues were related to the limited involvement of the analyst in the initial scoping of the work and the setting up of formal arrangements to reflect the extent and complexity of the clearances. The revision addresses this by advising allocation of more time to 4-stage clearances so that they can be properly scoped in a timely manner.
It is hoped that additional time should allow for adequate planning and sufficient clarity in the clearing process requirements so that adequate resources can be allocated. Additionally, this extra time should allow analysts to devise a suitable plan of work (POW) and to conduct an adequate risk assessment.
Soil sampling
This revision also recognises that there are some circumstances where there is asbestos in soil and made ground. In these cases, it is possible for workers to be exposed to asbestos during construction or other planned work activities. The Control of Asbestos Regulations 2012 (CAR) requires the identification of ACMs as part of the obligatory risk assessment.
Surveys are only required where there are reasonable expectations that asbestos may be present. There is no blanket requirement for soil sampling. Interestingly, CAR only applies to work settings so does not require surveys to be conducted for environmental risk assessments or for public health reasons.
“Differences between asbestos in soil and asbestos in buildings”
A notable area covered by the guidance is the “Differences between asbestos in soils and asbestos in buildings.”
The most noticeable difference being that ACMs in buildings are usually in the form of identifiable intact defined products with a known asbestos content. In soil, however, ACMs are more likely to be in various states of decomposition or degradation.
The decomposition of ACMs leads to asbestos fibres becoming embedded within the soil matrix. Normally, it is unlikely for these fibres to become airbourne, however, dried-out surface material may release fibres into the air when disturbed e.g. due to weathering or vehicle, human or animal disturbance.
The process of soil analysis methods
The new guidance further explains the process for soil sampling, with the aid of a flow chart:
And full details of the methods to be used for soil sampling are given in Appendices 1,2 and 7.
