If an ignition source introduced into a hazardous area could cause fire or explosion, the PCBU must ensure it is not introduced from outside or within the space (WHS Regulations r 355). Key measures: design buildings and plant to relieve and redirect pressure and flame; leak detection for flammable gas or vapour; intrinsically safe equipment; ventilation to prevent hazardous atmospheres; substitution with less flammable materials; segregating incompatible materials; reducing quantities of flammable and combustible material including pallets; eliminating ignition sources; maintaining equipment to manufacturer instructions; and cleaning to stop dust build-up. Hot work (grinding, welding, brazing, oxycutting, heat treatment and similar) near flammables creates significant risk, and work on drums, tanks and pipes not properly decontaminated is a common fatal scenario, so use a hot work permit system to control when and how it is done. Electrical equipment must be maintained and earthed, static electricity from transfers controlled, and auto-ignition temperature considered. A hazardous area is one where an explosible gas or combustible dust is present in a quantity needing special precautions for plant.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.