Conquer the BCSP Challenge 2025 – Elevate Your Safety Skills!

To calculate the 8-hour Occupational Exposure Limit (OEL) of 0.5 ppm for a 10-hour shift, the correct choice involves using the formula for the conversion of exposure levels across different shift lengths while maintaining a consistent standard for what constitutes a safe exposure level.

The formula used in the correct choice indicates a method of adjusting the OEL based on the ratio of the hours in the standard workday (8 hours) to the actual hours of exposure (10 hours in this case). The reasoning behind this conversion is to ensure that the health risks associated with exposure over the longer shift are also assessed in terms of a typical 8-hour exposure scenario, which is a common standard for measuring acceptable exposure levels.

The formula takes into account the relationship between the exposure durations. It considers both the duration of the exposure (in the 10-hour shift) and the permissible duration for which a worker can safely be exposed (the 8-hour threshold) while accounting for the remaining hours of the day.

In this case, the formula helps to translate the OEL from an 8-hour standard to ensure that the exposure level during a longer shift remains within safe limits. This ensures continued protection for workers during shifts that exceed the typical work period.