The first edition of this book was written as a response to the need for a comprehensive introductory-level text covering the major facets of occupational safety and health. The fourth edition of this book was written with the same objectives as previous editions: • It should be easily comprehensible by those who lack experience or prior exposure to concepts in occupational safety and health, industrial hygiene, or occupational medicine • It should be on a writing level easily understood by a majority of the population, yet be useful as a text for college courses • It should cover the major topics of concern to safety and health professionals and students to provide both with a philosophical base