This book on Environmental Science is strictly designed on the basis of the model curriculum prescribed by the AICTE for engineering undergraduate courses in India. It has been divided into six units. The first unit covers environment, its components and an overview of the environmental problems today. Second unit introduces ecology, and the principles of environmental impact assessment. Unit three covers atmospheric composition, energy balance, climate, weather, and dispersion. The fourth unit describes hydrosphere, water pollution and its control. Next unit elaborates lithosphere, pollutants, collection and disposal of solid wastes. Various aspects regarding noise pollution, its effects and control is explained in the sixth unit. This book is very useful for engineering undergraduates, general science students, educationists, policy makers and those preparing for competitive examinations.