Employee #1 was a maintenance technician at a company that performs epitaxial processes for semiconductor manufacturing. He reported to work in the fabrication area and was briefed by a coworker, also a maintenance technician, about the day’s projects. After a few minutes, other workers began to smell a strong chemical odor, and some saw a yellow or red cloud. They quickly evacuated the area. The coworker who had briefed Employee #1 investigated the source of the odor, which seemed to be near the acid sink in the fabrication area. He found Employee #1 standing under an emergency shower, surrounded by a yellow atmosphere. The coworker yelled for Employee #1 to leave the area and guided him to an emergency shower outside, at the rear of the building.