What does the 'applicable long-term exposure limit concentration' for a contaminant mean?

• A. Schedule 6 stated values for not more than 8 hour day or not more than 40 hour week; or adjusted having regard to a recognised standard for adjusting exposure limits for extended working hours for more than 8 hour day or more than 40 hour week.
• B. The instantaneous concentration allowed.
• C. The average concentration across the mine.
• D. A fixed limit only for CO2.

Answer: (A)

The applicable long-term exposure limit concentration is the maximum average airborne concentration of a contaminant that a worker can be exposed to over a standard reference period, typically an eight-hour workday or a 40-hour workweek. If shifts are longer than eight hours, the limit can be adjusted according to a recognised standard to account for the extended hours. The specific values are set out in Schedule 6, with these adjustments allowed when needed. This limit focuses on sustained exposure, not short-term peaks, and it applies to a range of contaminants, not just CO2.

It’s not an instantaneous peak limit, nor a mine-wide average, and it isn’t restricted to CO2.