Abstract: Prior to the accident, "A" Bleach Plant was down and awaiting inventory. Chlorine gas bypassed a block valve and was released from the "A" take-up chest. A chlorine alarm sounded and Zone 5 was evacuated and subsequently a mill-wide evacuation occurred. This resulted in employees working on paper machines H1 and H2 being exposed to chlorine during emergency shut-down operations. The mill-wide evacuation resulted in a loss of negative pressure on the non-condensable gas or NCG system. This allowed NCGs to vent at the lime kiln vent valve for approximately 48 minutes. Two employees from the Shipping Department who returned following the evacuation were exposed to these NCGs. A second Zone 5 evacuation was again conducted.