In March 2008, an International Brotherhood of Teamsters local union requested a health hazard evaluation at a flavoring manufacturing company because of concern about possible lung effects of flavoring exposures, including diacetyl. The National Institute for Occupational Safety and Health (NIOSH) staff evaluated spirometry data supplied by the company on production employees tested from 1998 through 2009. The majority of the spirometry tests were performed in the years 2004 and later. NIOSH findings and recommendations are detailed.