Workplace Exposure Standards (WES) are based on 8 hour shift exposures however many workplaces on Australia use a variety of extended work hours and shift rosters. Consequently, the WES value needs to be adjusted and there are a number of ways this can be performed depending on a variety of parameters eg: Chronic vs Acute health effects.
The AIOH have developed the WES Shift Adjustment Tool which has been based on the well accepted technical information currently available. The papers which give you the basis for the AIOH WES Shift Adjustment Tool have been attached:
AIOH Position Paper, Adjustment of Workplace Exposure Standards for Extended Shifts (2016).