3 Calculation of occupational exposure to air pollutants
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.729 – Design Guidelines and Operational Recommendations for Ventilation Systems in Ro-Ro Cargo Spaces – (Adopted on 4 July 1996) - Part 2 - Operational Recommendations for Minimizing Air Pollution in Ro-Ro Cargo Spaces - Appendix 3 - Recommendations for the evaluation of air quality in ro-ro cargo spaces - 3 Calculation of occupational exposure to air pollutants

3 Calculation of occupational exposure to air pollutants

  Long-term Reference Period

The occupational exposure over a 24-hour period is determined by treating the cumulative exposure over 24 hours as equivalent to a single uniform exposure. This is generally converted to an 8-hour time-weighted average (TWA) exposure and is represented mathematically by:

where C n is the occupational exposure and T nis the associated exposure time in hours in any 24-hour period.

Short-Term Reference Period

The short-term reference period generally relates to a period of 10 or 15 minutes, dependent upon the national occupational exposure standards. Exposure is therefore recorded as the average over a 10 or 15 minute reference period. Where the exposure period is less than 10 or 15 minutes, the measurement result is averaged over 10 or 15 minutes. Where the exposure period exceeds the short-term reference period, results are averaged for the 10 or 15 minutes period during which maximum exposure occurs.

Parent topic: Appendix 3 - Recommendations for the evaluation of air quality in ro-ro cargo spaces
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