I've been having some debate recently around the frequency of taking urine samples for SPMA testing of benzene exposure. The carrying out of baseline sampling (presample) is agreed for work with potential benzene exposure followed with post SPMA after exposure. It has been indicated that this act of post sampling should be daily on completion of shift, the question I have is that if there is sufficient data available of similar task/ exposure and controls would the frequency of sampling not be reduced. For example if the job ran over a few days then the post sample could be carried out on completion of exposure but at a point relative to increased levels. With every scope of work assessed in relation to levels of exposure and variable change and the frequency of sampling being relative to the assessment and historical control success, is this sufficient?