What is considered the best measure of incident severity?

The measure of incident severity is often quantified by the cost of damage and losses, making it the best choice among the options presented. This is because assessing severity through financial impact provides a comprehensive view of the incident's overall consequences. It encapsulates not only tangible losses, such as property damage, but also indirect costs, including potential liabilities, lost productivity, and long-term repercussions on the organization.

In incidents, particularly in a DoD context, understanding the financial implications helps in prioritizing response efforts, allocating resources efficiently, and informing decision-making processes. The cost factor can be critical in risk management and in planning for future incidents, as it serves as a basis for evaluating potential risks and the effectiveness of safety interventions.

Other options, while relevant to aspects of incident management, do not provide as holistic a view of severity. For instance, likelihood of occurrence focuses more on probability rather than impact; the number of injuries offers insight into human resource implications but may not fully convey the economic consequences; and apparatus exposure to disease is crucial for specific incidents but does not cover broader financial impacts. Overall, the financial cost aspect allows for a more thorough understanding of severity and necessary actions.