According to an article, Summing the factors of all individual hazards to determine their cumulative effect is reasonably valid assuming all hazards occur simultaneously or within a short enough period that their negative effects (i.e., injuries) would, in fact, be cumulative. Based on the critical factors associated with summing the severity of individual hazards as well as summing the individual probabilities of their occurrence, it becomes clear that to achieve an accurate result, the level of interdependence of the hazards in terms of severity and likelihood is crucial.