What must be done if the average concentration of respirable dust in the atmosphere cannot be reduced to the levels stated in the regulation?

• A. PPE must be supplied to the workers
• B. Controls for minimising dust must be reviewed
• C. The system must be changed to ensure average concentration is reduced to or below stated levels
• D. Provide ways of suppressing excessive airborne dust so a person's safety is not threatened

Answer: (C)

The key idea is that exposure limits must be met by the system that controls dust, not by relying on protective equipment or vague safeguards. If the average respirable dust concentration cannot be lowered to the levels set in the regulation, the appropriate action is to change the ventilation or dust-control system itself so that those levels are achieved. This follows the principle that engineering controls are the primary means of reducing exposure; PPE or ad hoc suppression methods do not reliably guarantee compliance with regulatory limits and are not a substitute for upgrading the system. By redesigning or modifying the system—adjusting airflows, improving dust suppression, changing layout, or implementing more effective control measures—the average concentration can be brought down to or below the stated levels.

Choosing PPE or simply reviewing controls does not ensure the required reduction on its own, and vague reductions in dust without addressing the system’s capability to meet the limit may still leave the exposure out of compliance.