LANGLEY AIR FORCE BASE, Va. -- Staff Sgt. Joseph Dunn, 633d Civil Engineer Squadron Fire Department firefighter, checks the status of Airman Jessica Howe, 633d Medical Group Dental Squadron assistant, after a chemical explosion during a Toxic Industrial Chemical/Toxic Industrial Material simulation here, Feb. 4. The Major Accident Response Exercise was held as a required semi-annual evaluation to examine first respnders' ability to quickly react and stabilize real-world emergencies.(U.S. Air Force photo/Airman 1st Class Racheal Watson)(RELEASED)