The intent of this pamphlet is to provide a simplified document to assist chlorine producers/users, local emergency planning committees, fire departments, and municipalities in estimating the area affected by a chlorine release for emergency planning and hazard assessment purposes, and to provide a general understanding of the expectations of chlorine cloud release scenarios.  The Department of Homeland Security (DHS) Chemical Security Analysis Center (CSAC), part of the Science and Technology Directorate (S&T), collaborated with the Chlorine Institute to develop updated guidance in this version of Pamphlet 74, based upon new experimental research into chlorine releases and the associated chemical and physical phenomena. The Hazard Prediction and Assessment Capability (HPAC) model, developed and widely used by the U.S. Government, was used to simulate the release scenarios in this pamphlet to provide new modeling results. 

(189 pages)