SHAW AIR FORCE BASE, S.C. -- Senior Airman Earl Barnes, 20th Aermedical-Dental Squadron bioenviromental engineering technician, uses a rangefinder to set up an intial cordon during a hazardous materails exercise April 9, 2009. The HAZMAT exercises help prepare Airman in 20th ADOS and 20th Civil Engineer Squadron to properly respond to real-world operations. (U.S. Air Force photo/Senior Airman Matt Davis)