Which factor is NOT a clue for the presence of hazardous materials?

The presence of hazardous materials is typically indicated by several specific factors that responders are trained to recognize. Transportation placards serve as a key visual cue, providing vital information about the substances being transported and their associated hazards. Monitoring and detection devices are employed to identify the presence of hazardous materials by measuring various environmental parameters, such as gas concentration or radiation levels. The shape of containers can also offer important clues; certain shapes may be characteristic of specific types of substances, indicating whether they pose a hazard.

In contrast, item expiration dates do not serve as a reliable indicator of hazardous materials. While expiration dates can provide valuable information regarding the usability or safety of certain products, they do not inherently indicate whether a substance is hazardous. For example, a chemical might be perfectly safe to use long after its expiration date, or it could be hazardous regardless of its date. Therefore, while monitoring hazard indicators is crucial, expiration dates are not a foundational factor in assessing the presence of hazardous materials.