Thank you all for responding – once again it is all very helpful. It also shows how each of us interpret slightly differently when/where to use a FB.
My opinion is that a FB would be used per test area/location and certainly per certificate as it would make sense. e.g. if you had 2 enclosures in the same building but in different locations/with different ACM being removed I would treat that as two separate tests.
I like norac_621481 reply – I’ve always thought of the FB regime to be a bit of a fudge as you could argue that every test needs a field blank attached to it, as conditions could be different for each test you do! I have a similar dilemma, particularly if you are doing personal monitoring on several different operatives in different areas who are working on different ACMs with different removal techniques.
The FB process also tracks possible contamination in the sample train: preparation of your cowled head, capping and uncapping at sampling site, then disassembly of the cowled head and mounting the filter on the slide.
I would like it if the HSE could clarify what is actually expected of an analyst when collecting FBs with specific detail so all the analysts are doing the same thing.