Wireless Sensor Networks (WSNs) are based on innovative technologies that had revolutionized methods in which we interact with the environment; i.e., through sensing the physical (e.g., fire, motion, contact) and chemical (e.g., molecular concentration) properties of the natural surroundings. The hardware in which utilized by WSNs is rapidly evolving into sophisticated platforms that seamlessly integrate with different vendors and protocols (plug-n-play). In this book, we propose a WSN framework which provides assistance with monitoring environmental conditions; we focus on three main applications which include: a. Air-quality monitoring, b. Gas-leak detection, and c. Fire sensing.