The National Institute for Occupational Safety and Health (NIOSH) received a management request for a health hazard evaluation (HHE) at the National Aeronautics and Space Administration Glenn Research Center (GRC) in Cleveland, Ohio. The request was about ongoing employee and union concerns about a possible higher rate of cancer among current and former employees of Buildings 500 and 501. A site visit was made in October 2008. NIOSH findings and recommendations are detailed.