What is a common factor in a hazardous material incident?

In a hazardous material incident, the defining characteristic is the release of harmful substances into the environment. This release can pose significant health risks to individuals exposed to the materials, including both first responders and the general public. Such incidents often require specialized responses and protocols to contain and mitigate the effects of the hazardous materials.

While the presence of multiple patients can occur in a hazardous material situation, it is not a defining characteristic; rather, it is a potential consequence of the release of harmful substances. The use of protective gear is essential for the safety of first responders but is part of the response to such incidents rather than a factor intrinsic to the occurrence itself. Implementation of Critical Incident Stress Management (CISM) may be utilized in the aftermath of a hazardous material incident to support responders emotionally, but it is not a common factor of the incident itself.

Thus, the release of harmful substances is central to identifying hazardous material incidents, making it the correct answer.