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The workplace exposure standards (WES) and biological exposure indices (BEI) are guidance values – not prescribed exposure standards (PES).

They are intended to be used as risk criteria for health risk assessment and risk management purposes and applied or interpreted only by people with appropriate training and experience, such as those qualified in occupational health practice.

While business must understand and manage the risks of hazardous or toxic substances at work, we do not recommend untrained people use WES or BEI to assess risk.

If you're new to these standards and indices

We suggest you read these pages first. They've got in-depth explanations and information that you'll find useful: 

More information

The following pages have more information about WES and BEI, including explanations of notations and a glossary:

Download document

You can search for WES and BEI information for substances using the search box on this page. Or, download the 14th edition of the book, effective from November 2023:

Workplace exposure standards and biological exposure indices – 14th edition (PDF 1.4 MB)