31 Workplace Exposure Standards and Biological Exposure Indices Guidance document The Workplace Exposure Standards (WES) are intended to be used as guidelines for people qualified in occupational health practice in workplace. This is a technical document focused on airborne monitoring for assessing health risk. Covers hazardous substances and mitigating health and safety risks even for those HS not covered by WES. Also covers workloads and extended shifts. Consultation closed on 21 November 2014