Abstract: At approximately 5:00 p.m. on May 20, 2003, three saw operators who work in the back of the warehouse became ill, complaining of nausea, dizziness and headaches. The employer called an emergency response team. Symptoms described by the employees alerted the fire department to possible carbon monoxide poisoning. The fire department took safety measurements in the warehouse and got readings around 400 ppm. Oxygen was administered to the ill employees then they were taken to the University of Maryland Shock Trauma where they were place in the hyperbaric chamber and received hyperbaric oxygen therapy. The employees' medical records showed elevated carboxyhemoglobin levels in their blood. The following day, MOSH visited the site and found that operations had been suspended. The warehouse was found to be airtight with no windows, doors and ceiling air vents opened. The carbon monoxide readings taken off the back of the three propane forklifts were past the monitors detection limit of 999 ppm. There are no other sources of combustion inside the warehouse.