What is the first action an employee should take if chlorine gas begins leaking in a room where they are present?

When chlorine gas begins leaking in a room, the immediate priority is to ensure personal safety and escape the hazardous environment. Keeping the mouth closed and maintaining an elevated head position can help minimize inhalation of the gas, which is crucial as chlorine is a toxic irritant that can cause serious respiratory distress. The recommendation to quickly exit the room while holding one's breath is an instinctive and often advised way to reduce exposure during the critical moments of evacuation, especially when immediate protective equipment or assistance is not readily available.

While the other options may have their own merits, the recommended action of quickly walking out while holding one’s breath focuses on immediate personal safety in a crisis situation. It emphasizes the importance of quickly removing oneself from the source of the leak. Properly trained personnel should seek assistance, but the immediate action of retreating from a contaminated area is vital in preventing the harmful effects of chlorine inhalation.