During the past two decades, many books, governmental reports and regu­ lations on safety measures against chemieals, fire, microbiological and radioactive hazards in laboratories have been published from various coun­ tries. These topics have also been briefly discussed in books on laboratory planning and management. The application ofvarious scientific instruments based on different ionizing and non-ionizing radiations have brought new safety problems to the laboratory workers of today, irrespective of their scientific disciplines, be they medicine, natural or life sciences. However, no comprehensive laboratory handbook dealing with aIl these hazards, some of which are recently introduced, had so far been available in a single volume. Therefore, it was thought worthwhile to publish this Handbook on safety and health measures for laboratories, with contributions from several experts on these subjects. As this second edition of the Handbook, like the first edition, is a multiauthor volume, some duplication in conte nt among chapters is unavoidable in order to maintain the context of a chapter as weIl as make each chapter complete. An attempt has also been made to maintain the central theme, which is how to work in a laboratory with maximum possible environmental safety.