Abstract: A GROUP OF EMPLOYEES WERE CONSTRUCTING A FIBERGLASS BOAT IN THE CHOPPER GUN AREA. THEY WERE WORKING WITH STYRENE MONOMER, METHYL ETHYL KETONE PEROXIDE, AND FIBERGLASS. THEY WERE RUNNING LOW ON MEK PEROXIDE, SO THEY ADDED THREE PARTIALLY FULL CONTAINERS OF WHAT THEY BELIEVED TO BE MEK PEROXIDE TO THE RESERVOIR. AS EMPLOYEE #1 RESUMED OPERATION OF THE CHOPPER GUN THERE WAS A SUDDEN EXPLOSION AND FIRE. LUCKILY, THE MAIN FORCE OF THE EXPLOSION BLEW AWAY FROM THE EMPLOYEES. THE EMPLOYEE WAS TREATED FOR MINOR CHEMICAL BURNS AND EXPERIENCED A TEMPORARY THRESHOLD SHIFT IN HEARING. LAB ANALYSIS REVEALED THAT THERE WAS A SIGNIFICANT AMOUNT OF STYRENE IN ONE OF THE MEK PEROXIDE CONTAINERS. CAUSAL FACTORS WERE DETERMINED TO BE EMPLOYEE LACK OF TRAINING ON THE PHYSICAL HAZARDS OF CHEMICALS, AND LACK OF LABELLING OF THE MEK PEROXIDE, WHICH CONTAINED STYRENE.