This year we’re consulting on Workplace Exposure Standards (WES) and Biological Exposure Indices (BEI). We’re proposing changes to the WES of 18 substances and the BEI of 4 substances. 

After consultation, we will consider your submissions in the WES & BEI review. When a decision is made it will be published in the WES & BEI book at the end of this year.

Please see the details on each substance that is up for consultation in the PDF list at the bottom of this page.

This consultation is open to everyone. We encourage you to share this consultation with any relevant industry groups, associations or individuals. 


We will manage any personal information you supply in accordance with the Privacy Act 1993.

If your response is made publicly available, your name and contact details will be removed only if you have selected this option on the survey form. We may post your response on this website and we may make your response available if answering a request under the Official Information Act 1982.

Deadline for feedback

Due to the COVID-19 situation, we acknowledge that submitters may not have the time to make submissions on the 2020 WES & BEI reviews. Therefore, the deadline for submissions has been extended to 28 August at 5:00 pm. However, we will be reviewing this deadline as the COVID-19 situation changes.

We will not be accepting submissions in any format other than through our online form.

This year we are consulting on Workplace Exposure Standards (WES) and Biological Exposure Indices (BEI). We’re proposing changes to the WES of 18 substances and the BEI of four substances. 

You may know about WES and BEI or heard other people talk about them – here is a brief explanation of what they are and why they are so important.

Workplace exposure standards (WES) are values that refer to the airborne concentration of substances at which it is believed that nearly all workers can be repeatedly exposed day after day without coming to harm.

A prescribed exposure standard (PES) means a workplace exposure standard or a biological exposure index that has the purpose of protecting persons in a workplace from harm to health and that is prescribed in—

  1. regulations; or
  2. a safe work instrument; or
  3. a control under section 77 or 77A, or an exposure limit under section 77B, of the Hazardous Substances and New Organisms Act 1996; or
  4. a group standard approval issued under section 96B of the Hazardous Substances and New Organisms Act 1996

Currently there are no WES prescribed in regulation, no Safe Work Instrument for WES/BEI, and no WES set in current Group Standards. There are some PES set via Sections 77, 77A or 77B of the HSNO Act 1996 including methyl bromide and 1080. The WES and BEI values discussed in this consultation and all other WES in the WorkSafe WES/BEI book (except methyl bromide and 1080) are not PES and are therefore guideline values. They are intended to be used by people with the appropriate knowledge, skills and experience to apply them for health risk assessment.

A robust sampling strategy is critical when applying WES to ensure a good understanding of exposure variations which always occur. Exposure levels are commonly variable even in work that is regular and consistent. Variation in worker exposure arises from variation in work activities, control methods and environmental conditions. Due to this variation, exposure measured on a single day may not reflect exposure on other days. Multiple samples generally allow for better understanding of the variation in exposure, and thus provide more detailed information for the risk assessment. However, even samples from multiple days may not reflect the true variation in exposure that may occur over the long term. With this in mind, the PCBU should take advice from a competent person on how exposure should be monitored in the workplace, including the sampling strategy. The sampling strategy must be designed to provide sufficient measurements to reflect the risk to the worker from the variation in exposure.

BEI (Biological Exposure Indices) are guidance values for assessing biological monitoring results.  Biological monitoring measures the concentration of a substance – or its breakdown products - in blood or urine or even exhaled air and the monitoring result is compared to the BEI established for the specific substance.

For substances that can be readily absorbed through skin as well as inhaled, biological monitoring may be the preferred exposure monitoring tool, as measuring air levels alone may not fully represent exposure. However, options on biological monitoring are limited as there are few biological exposure indices, compared to exposure standards for airborne monitoring. 

Biological and airborne exposure monitoring should not be confused with health monitoring. Exposure monitoring means the measurement and evaluation of exposure to a health hazard experienced by a person; and includes monitoring of the conditions at the workplace, and biological monitoring of the people. Health monitoring, in relation to an individual, means monitoring of the individual to identify any changes in his or her health status because of exposure to certain health hazards.

Health risk management must consider a number of aspects from identification, to assessment, to control, with exposure monitoring being just one part – not the only part that needs to be considered.

PCBUs must minimise exposure and monitor the conditions of the workplace if the exposure cannot be eliminated. WES and BEI are important tools for monitoring worker exposures.

While PCBUs must understand and manage the risks of hazardous or toxic substances at work, we do not recommend untrained people use WES to determine compliance. WES are guidance for qualified occupational health practitioners.

Further information on WES, including the meaning of WES-TWA and WES-STEL, and BEI is provided in the Glossary sections of the relevant proposal documents.

If you wish to make a submission, it would be worth having your responses ready, so you can copy and paste them into our submission form. To assist with that, an example of the general format of the questions is as follows:

  • Do you agree with the proposed adoption of the WES-TWA of 100 ppm?
  • Comments on the proposed adoption of the WES-TWA value?
  • Do you think exposures below the proposed WES-TWA are feasible to achieve?
  • Comments on the feasibility of meeting the proposed WES-TWA value

Some questions relate to the removal of WES values (where appropriate), special notations and analytical methods.

Step-by-step guide for submitting feedback

  1. Click on the “Workplace Exposure Standards (WES) and Biological Exposure Indices consultation form” below, and you will be directed to a survey page with a checklist of the WES and BEIs for consultation.
  2. Check the boxes of the substances you wish to provide consultation for. You can provide consultation for more than one substance simultaneously.
  3. It’s a good idea to have what you want to say already written in an electronic document, so you can copy and paste your comments into our online form, and complete your consultation for multiple substances in one go.
  4. When you have completed your comments for a substance, at the bottom of the page, click ‘Next’ to move on to the next substance (if you’ve chosen more than one).
  5. If you have completed your consultation, upon clicking ‘Next’ at the bottom of the page, you will be brought to a page with final notes. You can close that window as your submission will have been received – there will not be an email sent out in acknowledgement of completion.