This is a free, online textbook. According to Textbook Revolution, "This book on radiation was in print for two editions, but now that it is out of print the copyright has reverted back to the author. Professor Hunt has updated it, changed the copyright to a creative commons license, digitized the book, and asked Textbook Revolution to host the files. We’re proud to be the sole online source of this text. From the text: In the post-nuclear era the word ‘radiation’, in the popular lexicon, has taken on a specialized and negative meaning. Largely because of media misinterpretation the word now suggests to the non-scientist the malignant effects associated with the misuse of nuclear energy. But ‘radiation’ is not all harmful, nor indeed is it all nuclear in origin. It is essential, …, that we be able to understand radiation, be able to measure it in a reproducible way, and as a result of our understanding and measurements, be able to control it and protect ourselves and the public. Not all of the radiation of environmental concern is electromagnetic… or consists of particles…. Sound is also radiation and has an environmental impact, usually in the form of ‘noise’. Although there are certainly physical effects of intense sound, much of its impact depends on our psychological reaction, and so the subject of ‘psychoacoustics’ has been developed to measure human perception of sound radiation. Because so much of the natural radiation is electromagnetic, a review of electric and magnetic fields in Chapter 1 leads to a consideration of the properties of EM waves from a classical point of view in Chapter 1 and a quantum point of view in Chapter 2. Chapter 3 covers the measurement of visible light, a subject known as ‘photometry’. Here the human perception (seeing) of the physical phenomenon (EM waves) introduces the reader to one aspect of psychophysics and a plethora of new units and measures. Chapters 4 and 5 discuss the environmental effects of visible and UV radiation, and infrared and radio radiation respectively. Chapter 6 describes the construction of lasers and their classification by output power. This leads to an analysis of the hazard of laser radiation and the standards that have been established to minimize risk. Chapter 7 discusses the physics of nuclear radiations, and Chapter 8 their interactions with biological systems, and the associated hazards. Chapter 9 is a brief survey of some nuclear radiation detection and monitoring methods. Chapters 10 and 11 introduce sound radiation and the measurement and classification of a selection of examples of environmental noise. Comment by the author: I wrote this book when I was given the assignment to develop a course on Environmental Radiation for Life Science students in Environmental Studies at the 2nd year level. I was astonished to find that there were no texts on the subject at that level;, that is, with a preparation of one course in Physics and one in Chemistry. Graduate texts and Research monographs yes – but not at the intermediate level. To my knowledge it is still the only one."