Abstract: At 7:15 p.m. on May 3, 1988, two employees from Gallo Mechanical Contractors, Inc., were installing a drainage pipe for a sink in the floor of the change area in the examination room of a linear accelerator that was being constructed. They were using a gasoline-powered masonry concrete cutter in an unventilated area to perform the cutting. Three employees from Brice Bldg. Co., Inc., were performing demolition work nearby: drilling holes in the wall, chipping concrete, and cutting reinforcements in the wall in the accelerator area (number 20). The three employees from Brice Bldg. Co., the two employees from Gallo Mechanical Contractor, and one employee from GMCI were overcome by carbon monoxide from the gasoline-powered concrete cutter. One employee died and five others were hospitalized. (The GMCI employee was listed on an injury line under the inspection number for Brice Bldg. Co.)