Since September 11th the need to train civilian response personnel to cope with terrorist activity has greatly intensified; yet affordable and effective training methodologies are elusive. The First Responder Simulation and Training Environment (FiRSTE) system is built to address this situation. Its purpose is the application of virtual reality simulations for training civilian first responders to deal with weapon of mass destruction events in a zero-risk environment while applying proper procedures, techniques, and protocols. Underwritten through support from the Tank-automotive, and Armament Command, FiRSTE is designed to accommodate personal protection equipment, be physically stressful, mentally challenging, compatible with federal simulation standards, and portable. Since the target training audience includes rural and small town civil responders, FiRSTE was built using inexpensive components to demonstrate the affordability of such training technology. Forward motion control in the virtual environment is driven by the trainee walking on a treadmill modified to communicate with a gaming engine via a data acquisition card. The trainee holds a mock-up of a Photo Ionization Detector (PID) which has the same mode control buttons as the actual device. The virtual environment is viewed via a head mounted display placed within the mask of a self-contained breathing apparatus. A mouse wheel embedded in the PID mock-up provides directional control. The release of chemical toxins within a building and the associated sensor behavior is simulated using HLA-compliant software developed by the investigators. Three concept exploration phases have been performed using local firemen. Quantitative and qualitative measures were collected, and analyses were carried out with the goal of evaluating: a) the nature of users' navigation through the environment; b) the degree of perceived fidelity and presence; and c) subjective and objective effectiveness of the training tool.