and multi-servicemasks were provided. Advice was given on precautions to be taken during machining of zirconium. The health problem is minimal but the fire hazard is at least equal to that involved in machining magnesium. Group H-3 was advised of this activity. Air samples were collected in Building 340 at S Site to estimate the exposure to butyl acetate. All concentrations found were below the permissible level, but a definite nuisance exists during peak concentrations. At the request of the Zia Company, an investigation was made of the cause of dermatitis on a Zia plumber replacing the Duriron sewer lines in the new Physics Building. No specific agent was identified but acids and organic mercury compounds are suspected. Group,H-5 consulted with Group H-1 on the. radon gas exhaust problem of Group pag.testticatton changed to ae ad ode U.S.E.R.D. As H, Ventilation Per lng? PSa (Forzon authoricigy change in ¢ Won ti during th} Several new ventilation systegs were p fod and (Date) others have been installed. tur These inelude*1# arf Panteraekdye tnoTeOhep, ave G4 e) lation and air cleaning systems for the new Radiochemistry Building, and the new Sigma Building. At TD Site three new hoods have been recommended and plans discussed, Several conferences have been held for the best means of exhausting a soldering bench in the basement of P Building. designed for use by Group P-l2, An acid fume scrubber has been A new Reumlin local exhaust hood has been installed in the welding shop at SM-39. Should this flexible unit prove suc- cessful, it probably will be installed in other welding booths in this shop. Slot-type ventilation has been recomuended for welding and soldering work in Shop 4 where some soldering will be done on cadmium-plated metal. A number of changes have been made or recommended in the existing exhaust systems. These include the grinding room in Shop 8, Building 380 at S Site, Building 370 at S Site, the cut-off saw in Sigma Building and the hood system ‘tis [ED /Dog es 47