YOKOTA AIR BASE, Japan -- Senior Airman Anna Hurlbert, 18th Aerospace Medicine Squadron, monitors radiation levels in the air here at Yokota Air Base, Japan, March 24, 2011. Airman Hurlbert, on temporary duty from Kadena AB, is assisting Yokota's Medical Group to monitor base radiation levels in support of Operation Tomodachi. (U.S. Air Force photo/Master Sgt. Jeromy K. Cross)