On February 11, 1998, the U.S. Forest Service (USFS) requested that a representative of NIOSH conduct a health hazard evaluation (HHE) to evaluate and compare timber marker's (also called Forestry Technicians) exposures to a new waterborne formulation of tree marking paint developed for use by the U.S. Forestry Service. NIOSH performed several previous investigations to document Forestry Technician's exposures to alkyd enamel tree marking paint traditionally used by the USFS for timber marking operations. On May 18, 1998, two NIOSH industrial hygienists met with USFS employees and management representatives in LaGrande, Oregon, where an opening conference was conducted to discuss details of this investigation which occurred on may 19-21, 1998, at the Little Bear timber sale in the Catherine Creek Wildlife Unit located approximately 25 miles southeast of LaGrande.