A PCBU must manage the risk to health and safety from a hazardous atmosphere or an ignition source in one. Fire and explosion need fuel, oxygen and an ignition source. Identify fuels: flammable chemicals including vapours and fumes, other fire-risk substances such as pyrophorics and water-reactive substances, and non-hazardous combustibles such as wood, paper and leaves that add fire load. Identify oxygen sources such as oxygen gas, compressed air, oxidisers and peroxides. Identify ignition sources of three kinds: flames (welding flames, heaters, pilot lights), sparks (welding arcs, electric motors, switches, static electricity, lightning, friction from grinding) and heat (hot surfaces, engines, exothermic reactions), including those next door or arriving periodically such as delivery vehicles, visitors and portable tools. Not all electrical equipment is an ignition source if it is intrinsically safe. Gas-generating reactions can also cause pressure explosions.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.