Which of the following is a visual indicator of a hazardous material release?

• A. Hissing noises.
• B. A noticeable odor.
• C. Mist, colored smoke, vapor clouds, fires, leaking containers, or spilled liquids.
• D. Temperature change.

Answer: (C)

Visual signs are the quickest way to recognize a hazardous-material release because they show material escaping or reacting in the environment. The description that includes mist, colored smoke, vapor clouds, fires, leaking containers, or spilled liquids is the best fit because these are observable, physical signs you can see and use to know a release is occurring. Hissing is a sound, not something you see; a noticeable odor is smelled rather than seen; a temperature change isn’t a visual cue. Seeing these visible indicators helps you take immediate protective actions and respond safely.