A prescribed mine's operator must ensure that air throughout places where people work or travel, or may work or travel, is kept at a safe level; that the atmosphere is controlled to prevent thermal stress; that humidity is kept at a level allowing work to be done safely; and that lighting is sufficient for safe work. Air counts as safe if its oxygen level is safe and it holds no contaminant or impurity at a harmful level, which includes a hazardous substance, or any ingredient of it, above the applicable exposure standard, if one exists.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.