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ISBN 0-036712-31-7 1962, 1966, 1971 by American Conference of Governmental Industrial Hygenists, Cincinnati, OH. 1980 by American Conference of Governmental Industrial Hygenists, Inc., Cincinnati, OH. All rights reserved. No pari of this book may be reproduced in any form or by any means without written permission from the Executive Secretary. American Conference of Governmental Industrial Hygenists, Inc., 6500 Glenway, Bldg. D-5, Cincinnati, OH. 45211. Printed in the U.S.A. } ....................................................... _ ^ HFM-009712 8002 0450 oorwtrcn r>v men