Hi All, We have just received a report from an external company for a dust survey that they carried out. The following quote below is in the report. The 10% level of significance is used by the HSE as a guidance level for “as low as reasonably practicable”. Can anyone point me in the direction of where this phrase can actually be found in any guidance notes, regulations etc. your thoughts would be appreciated. Kenny G

This may be intended to refer to sampler bias, as described in MDHS14/3. Not sure how this can be related to sfarp though. MDHS 14/3 is quite specific about acceptable levels though. That document explains that where there is no indication of the need for a lower value (e.g. substances specifically listed in EH40) then a concentration of 10 mg m-3 (8-hour time-weighted average) of total inhalable dust or 4 mg m-3 (8-hour time-weighted average) of respirable dust is to be considered a 'substantial' concentration of dust. Hope this helps.