Abstract: At 4:00 p.m. on May 10, 2021, an employee working for a chemical supplier was transferring chlorine containing product from a storage tank into a tanker truck. A valve meant to direct the displaced contaminated air to be scrubbed of chlorine was accidentally not opened. The chlorine containing air was then not scrubbed and was allowed to escape into the atmosphere. Employee #1 was overcome from exposure to chlorine vapors and had to evacuate. Employee #1 contacted Employee #2 via radio and informed Employee #2 of the need to evacuate the area. A coworker happened to be in the area and heard Employee #1 inform others to evacuate so the coworker pulled the emergency stop valve which stopped transfer of all materials in the building. Employee #1 and Employee #2 were transported by ambulance to the hospital and were admitted for treatment due to lung damage from chlorine exposure.