This book puts together a body of very recent information never before presented in one volume on the design of post-release mitigation systems. The development of a fundamental knowledge base on post-release mitigation systems through testing and data correlation is very new. While further research and development is needed this practical work offers guidance on putting post-release countermeasures to work now. The book presents current engineering methods for minimizing the consequences of the release of toxic vapors or ignition of flammable vapors including passive and active systems intended to reduce or eliminate significant acute effects of a dispersing vapor cloud in the plant facility or into the surrounding community. As in all CCPS works the book emphasizes planning and a systems approach shows limitations of any methods discussed and provides numerous references so that the reader may continue to learn.