Which of the following is a common indicator of a hazardous material leak?

Unusual odors or visible vapors are indeed common indicators of a hazardous material leak. When hazardous materials are released into the environment, they can emit strong or abnormal smells due to their chemical composition. This distinctive odor often serves as a warning sign that a dangerous substance may be present. Additionally, visible vapors or fumes can indicate that a material is evaporating into the atmosphere, which can be particularly dangerous if the material is toxic, flammable, or otherwise harmful to human health and the environment. Recognizing these signs is essential for early detection and response to potential hazards, allowing responders to take appropriate safety measures.

In contrast, stable temperatures and pressure typically suggest that a system or container is functioning as intended, which would not indicate a leak. Clear air quality readings would imply there are no harmful substances present, thus negating the possibility of a leak. Normal noise levels in the area would further imply that there are no disturbances or issues that might suggest a hazardous material situation. Therefore, the presence of unusual odors or visible vapors is a critical factor in identifying a hazardous material leak.