Which two parameters are essential to define the level of risk?

The correct choice emphasizes the fundamental aspects of risk assessment: event likelihood and consequence severity. In the context of risk analysis, "event likelihood" refers to the probability or frequency with which a potential hazardous event might occur. This parameter is crucial in determining how often risks may manifest. On the other hand, "consequence severity" deals with the potential impact or harm that could result from the event if it were to occur. This could include financial losses, harm to people, environmental damage, or other significant repercussions.

Together, these two parameters form the basis for a quantitative risk analysis framework. Assessing both the likelihood of an event and the severity of its consequences allows practitioners to evaluate risk effectively and to prioritize safety measures based on their potential impact. This understanding is instrumental when applying Layer of Protection Analysis (LOPA), where you can assess whether the existing safeguards are adequate to mitigate risk to an acceptable level.

In contrast, the other choices do not encapsulate the essence of risk definition as thoroughly. For instance, while event impact and cost estimation can be relevant in risk management, they do not directly define risk itself. Similarly, time of occurrence and resources needed may relate to project planning or operational management but miss the fundamental risk parameters of likelihood and severity. Lastly