Volatile organic compounds (VOCs) are hazardous highly toxic pollutants that cause a number of environmental and human health problems. They are released during a wide range of industrial, transportation and commercial activities and their emissions have reached high levels. This book provides a review of the occurrence, behavior and ecological implications of VOCs. Chapter One evaluates the biogeneration of volatile organic compounds produced by microalgae. Chapter Two investigates VOC pollution from industrial complexes and wastewater treatment plants (WWTPs). Chapter Three illustrates the current knowledge of intra- and inter- organismal Microbial Volatile Organic Compounds (mVOCs)-based interactions, volatile perception, signal transduction and phenotypical responses in the receiver organisms. Chapter Four summarises the current state of knowledge regarding the impact of emissions from gasoline powered vehicles on historical ambient VOC concentration trends, and on the current ambient urban atmosphere of the South Coast Air Basin. Chapter Five discusses the oxidation of VOCs over cyptomelane catalysts. Chapter Six studies VOCs from truffles and false truffles from Basilicata in Southern Italy. Chapter Seven discusses the removal of VOCs in the air by total catalytic oxidation promoted by catalysts.