At what concentration must hot work be stopped if occurring underground?

Hot work activities, such as welding or cutting, can pose significant risks in underground mining environments, particularly due to the presence of flammable gases and dust. To ensure safety, specific concentration thresholds have been established for when hot work must be halted due to the risk of explosion or fire.

In Queensland mining regulations, the concentration threshold for hydrocarbons is set at 0.5% (5000 ppm). When the concentration of flammable gas reaches this level, it is deemed unsafe to continue any hot work activities. This standard is based on the understanding that even at relatively low concentrations, the potential for ignition increases significantly, particularly in enclosed or poorly ventilated spaces like underground mines.

Thus, stopping hot work at concentrations greater than 0.5% effectively mitigates the risk of accidental ignition and enhances the safety of all personnel in the mining operation. This guideline ensures compliance with regulatory safety standards and reflects best practices in managing hazardous conditions in underground environments.