Adjustment of Workplace Exposure Standards for Extended Work Shifts (2016)

Most mining and many other industries now work extended work shifts. The standard eight‐hour day, the epidemiological basis of almost all current exposure standards for atmospheric contaminants, no longer exists in many workplaces. For this reason, exposure standard adjustments have now become an essential component in workplace health assessment.

This is a significant change as exposure standard adjustments have generally been considered as applying to ‘unusual’ work shifts. These are now no longer unusual, but the norm in many industries.

A major problem is that there are significant differences in the various adjustment methods available, some mandated or implied in various jurisdictions across Australia, resulting in significant differences in adjusted exposure standards. This is potentially confusing and inequitable to those who are potentially exposed to health affecting agents in the workplace.

This paper provides an overview of the exposure standard adjustment methods for atmospheric contaminants, a selection of legislative approaches in Australia and other countries and examples of the varying outcomes. It then proposes a potential way forward based on national and international consistency to provide those exposed in the workplace to consistent and appropriate information. The paper is not intended to provide a definitive methodology for adjusting atmospheric exposure standards, nor is its intent to review the underlying principles and mechanics of the adjustment models, as these are well documented in the referenced publications.
This paper does not address the adjustment of personal noise exposures as this is clearly defined in Australian/New Zealand Standard AS/NZS 1269.1.

The paper does not address exposure assessment methodologies. The AIOH recognises that appropriate exposure assessment methodologies
are required to get meaningful exposure data prior to assessment against time weighted exposures. The AIOH position is that the current guidelines and legislative framework across Australia can lead to inconsistent advice for affected workers. The AIOH recommends moving to a single model based on the ‘Quebéc model’ that references Australian Workplace Exposure Standards (WES), is computer‐based, utilises current toxicological information and can provide consistent guidance.