What must the VO ensure for atmosphere containing contaminants?

• A. Every worker is trained in contaminant response.
• B. The mine is evacuated whenever any contaminant is detected.
• C. The person is not exposed to an atmosphere at the mine containing a Schedule 6 column 1 contaminant that has a GBC exceeding its long-term exposure limit, except when wearing self-contained breathing apparatus in an emergency or for mine rescue.
• D. Contaminants are allowed if PPE is worn.

Answer: (C)

The main idea here is preventing workers from entering atmospheres that are more hazardous than allowed. The rule requires that no person at the mine be exposed to an atmosphere containing a Schedule 6 column 1 contaminant if the contaminant’s GBC exceeds its long-term exposure limit. The only acceptable exception is when a worker is wearing a self-contained breathing apparatus in an emergency or for mine rescue. This ties the exposure limit directly to the protective measures needed, ensuring that only the proper respiratory protection is used in critical situations rather than relying on training or general PPE.

Why this is the best fit: it states a clear, enforceable condition about exposure limits and the exact protective measure allowed in emergencies, which is what a VO is responsible for enforcing to keep people safe.

Why the other ideas don’t fit: training alone doesn’t change the atmospheric hazard or enforce the exposure limit; evacuating the mine for any detected contaminant is unnecessarily broad and not what the rule requires; and allowing contaminants with PPE ignores the exposure limit and the required use of SCBA in emergencies or rescue situations.