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L <br /> A' <br /> Inter-office <br /> Memorandum <br /> TO' Regional/Divisional Safety Officers cc: <br /> QA/H 5 Staff � <br /> I <br /> i <br /> FROM: George M. Crawford � DATE: 2 August 1988 � <br /> PROJECT: W.0' 'No.: <br /> SLBJECT: Benzene Action Leval Guideline <br /> ACTION: <br /> As many of you are aware rulings by OSHA have resulted in a <br /> decrease in the Permissible Exposure Level (PEL) for Benzene to <br /> 1 . 0 ppm. This ruling has resulted in a need to establish action <br /> level for job sites/activities where benzene may be listed as a <br /> constituent of the contamination suspected. These activities <br /> would include but, not necessarily be limited to gasoline spill <br /> response, tank excavations, and drilling activities where <br /> gasoline or petroleum constituents are encountered. <br /> BENZENE ACTION LEVEL G <br /> ,. VE UIDELINE <br /> 1) Monitor Drgahh .na Zone contaminant concentrations with <br /> Direct Reading Instruments sensitive to aromatic compounds <br /> (ag. OVA, HNU) , <br /> 2) If readings beach 1 to 5 units above background then Level <br /> G, protection 'will be required, <br /> 3) When 5 units above background are reached with <br /> direct-reading instrumentation then levels must be <br /> monitored with colorimetric tube indicators sensitive to <br /> 0. 5 ppm Benzene. <br /> i <br /> 4) If coloximetr'ic tube readings indicate less than 1 . 0 ppm f <br /> then Level C operations can continue. Periodic <br /> surveillance with the colorimetric indicators should <br /> continue. <br /> S) If colorimetric tube readings indicate 1. 0 ppm benzene or <br /> greater for two (2) successive readings taken 10 minutes <br /> apart then Level B protection must be effected. <br /> Note: Irrespective of colorimetric tube indications Level B <br /> protection will be initiated should direct reading instrument <br /> concentrations reach 500 units above background during gasoline i <br /> Clean ups on tank excavations. <br />