Alpha Tracker is correct. The latest version of the Analysts’ Guide provides information on monitoring to lower levels of sensitivity so that we try and get everyone to move away from using the clearance indicator for all types pf sampling. Box A1.3 gives some examples of reporting results which include 3 and 4 decimal places. We need to focus on background levels which are stated as 0.0005f/ml and have been upheld as that in the courts of law.
The NORAC AGM in September has a session with regards to better sensitivity, how to achieve and why we need to be assessing down to background level where we can.
Colette