This book discusses the environmental aspects of oxidative stress and also provides up-to-date information regarding antioxidants. Various applications of oxidative stress theory under the impact of environmental factors on biological systems have been discussed in this book comprising of induction of oxidative stress by biological, physical, and chemical factors in animals, fungi, plants and humans. The physical factors described herein include exercise, light and temperature; chemical induction is associated with pesticides and metal ions, while the biological factors elucidated include host-pathogen interplay and the impact of stress on secretory system. Antioxidants, which comprise of a wide spectrum of individual compounds and their mixtures of natural origin and those chemically synthesized to avoid or restore negative impacts of reactive species, have also been elucidated in this book. It will serve as a valuable source of reference for graduate and postgraduate students, physicians, environmentalists, and researchers.