This book is intended for an introductory course on environmental engineering for the first year students. It covers the syllabus designed to meet the requirements of EAT 103 - Introduction to Environmental Engineering, a first year level course in the first degree environmental engineering programme offered by the School of Environmental Engineering, Universiti Malaysia Perlis or UniMAP. It touches on the principles underlying the knowledge and practice of environmental engineering. This book contains 5 chapters. It sets to guide students on the major elements in this branch of engineering. These elements form the foundation upon which students will be later exposed to a more deeper understanding of the knowledge and practices of environmental decision making and management enshrined in various advanced courses that they will have to go through as they proceed to years two, three and four. The first chapter gives an overview on the definition of the environment and its associated issues. It also discusses briefly on the environmental law and its related regulations. The Malaysian Environmental Quality Act 1974 is referred to most of the time, albeit not deeply. This act together with its related regulations and directives will be covered in more details in the second-year EAT 207 – Environmental Law, Safety and Health, a course designed as continuity to the EAT 103. The second chapter discusses briefly on noise pollution. This topic will be further discussed sufficiently in EAT 302 - [Noise Pollution and Vibration Control], a course offered at the third year level. The third chapter deals with the subject on hazardous wastes and how they are managed. Students will find it useful when they follow an ensuing EAT 206 – [Solid and Hazardous Waste Management], a second year course dedicated to this subject. The fourth chapter provides an overview on air pollution and it will be covered in sufficient details when the students are in their third year. Last but not least, students will be introduced to water pollution. This topic is a prerequisite to EAT 303 – [Wastewater Engineering]. All topics in these chapters are discussed with examples and selected solutions to given problems, emphasizing relevant scientific principles. They are also discussed in the light of their related legislation. It is hoped that the students will understand reasonably well on the principles of environmental engineering and are better prepared to follow other pertinent courses later.