The goal of Shelter-In-Place (SIP) is to reduce human exposure to chemical, biological, radiological, and nuclear (CBRN) agents in the event of an accidental or intentional airborne release into the outdoor environment. THe Air Force Bioenvironmental ENgineering (BE) career field is responsible for providing sampling, identification, and quantification input to hazard prediction models and supporting evacuation plan development to provide risk-based control recommendations to the Incident Commander. This also includes providing exposure and contamination control recommendations for sheltered populations. A Gaussian plume model combined with indoor box model was used to test the consequences associated with the delay of implementing SIP procedures. It is imperative that emergency planners pre-plan the installation SIP protocol for likely scenarios identified during the various vulnerability surveys. THe decision to shelter-in-place must be made immediately in order to reduce the exposure and thereby decreasing any additinoal casualties presenting at the local medical treatment facility.