What does the 'maximum exposure limit concentration' for a contaminant mean?

• A. The long-term exposure limit concentration.
• B. 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 extended hours.
• C. The time-weighted average over a shift.
• D. The concentration used for emergency planning only.

Answer: (B)

The key idea is that the maximum exposure limit concentration is the regulatory airborne concentration you must not exceed for the standard working period. In this context, it is defined by Schedule 6 values for not more than an 8-hour day or not more than a 40-hour week, with adjustments allowed if extended hours are used under a recognised standard. This means the limit is tied to a specific time frame of exposure and is meant to reflect what a worker can safely be exposed to over that typical schedule, not just a single moment or a purely long-term lifetime limit.

This is why the option referencing Schedule 6 values for the standard 8-hour day or 40-hour week (and adjustments for extended hours) is the best choice. It captures both the time frame and the regulatory basis for the limit. The other ideas either point to a different kind of limit (long-term exposure) or describe a slightly different concept (time-weighted average over a shift) or a use that doesn’t define the general workplace limit (emergency planning only).