What must the VO provide for in regard to the general body concentrations for particular gases and contaminants?

• A. The atmosphere in each part of the mine has a general body concentration that is—For a contaminant in schedule 6 column 1 ALARA and within the limits to which a person is allowed to be exposed under section 359, For O2 at least 19%, For methane not more than 2.5%, For CO2 - ALARA and within the limits to which a person is allowed to be exposed under section 360
• B. A fixed oxygen level of 20.5%
• C. No limits to gas concentrations
• D. Only oxygen matters

Answer: (A)

The general body concentrations are the target values the VO must establish and maintain in every part of the mine to keep the atmosphere within safe limits. Oxygen must not fall below 19% to ensure reliable respiration; methane must be kept at or below 2.5% due to explosion risk; carbon dioxide is managed using ALARA principles and within the exposure limits set by the relevant sections; other contaminants listed in schedule 6 column 1 are also controlled under ALARA and the exposure limits. This comprehensive approach reflects that multiple gases and contaminants require managed levels, not a single fixed value or no limits, and not a focus only on oxygen.