English: The pyramid formulation of the interrelated elements of the hierarchy of control can be used to provide retrospective, contemporaneous, or prospective insights about the sustainability and levels of risks associated with work activities that involve different combinations of hazards, exposures, controls, and resulting risks. For example, elimination of a hazard is considered to be a highly sustainable strategy, and if a hazard was or is thought to have been eliminated from a process, then initial evaluations can focus on confirmation of material inventories and process knowledge. Similarly, control situations that rely heavily on engineered controls, warnings, work practices, or use of PPE are less sustainable and involve greater risks, and risk management evaluations can focus on confirmation of whether those controls were actually in place and properly applied.