What visual indicator is associated with a chlorine leak?

The visual indicator associated with a chlorine leak is characterized by the presence of white vapor near the floor. When chlorine gas escapes into the atmosphere, it can react with moisture, forming hydrochloric acid and other compounds that can appear as a visible vapor. This vapor tends to be denser than air, which is why it often accumulates close to the ground. Recognizing this indicator is crucial for safety, as it allows personnel to take immediate precautions to prevent exposure to the toxic gas.

While other options may address different aspects of monitoring or assessing chlorine systems, they do not accurately describe the specific visual sign characteristic of a chlorine leak. Therefore, the identification of white vapor serves as a critical alert for safety measures in areas where chlorine is present.