Risk is the probability that a hazard will become a problem [1]. In risk assessment, it is usual for risk criteria to be formally identified (e.g., Bui et al. [1]). First, it is necessary to determine what hazards contribute to the risk of the problem occurring. Second, criteria that need to be evaluated in order to determine the risk have to be established. Finally, it is necessary to ascertain at what level the hazard will become a problem.