I have wondered whether or not previous lab analysis for asbestos presence was just not as good as modern testing. I have a site in mind where we undertook plenty of testing with no positive results and then a few years ago we were finding asbestos everywhere at very low concentrations, typically <0.001%. You can only work with the results you have and if in the past you were told be a competent lab that there was no asbestos you proceeded on that basis, if the testing methods used now are capable of detecting presence at much lower concentrations then you work with these results. We do caveat our work with words along the lines of "undertaken using current standards and take no responsibility for amending in light of future developments" which is I think reasonable. Certainly any 10 year old report that crosses my desk gets read in the context of the date it was written so any conclusions made about the lack of asbestos presence would be considered in light of the practices undertaken at that time and a level of skepticism apportioned appropriately.
Clive
I'd just like to add that the last few days' contributions to the list on a number of topics have been fantastic and really demonstrate the breadth of knowledge and engagement there is out there amongst you all. Its been a pleasure dipping in, I learn a great deal from this list.
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