RoB-SPEO: A tool for assessing risk of bias in studies estimating the prevalence of exposure to occupational risk factors from the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury.

•WHO and ILO are systematically reviewing occupational exposure prevalence studies.•Assessing risk of bias (RoB) in individual studies is a core step of systematic reviews.•We developed RoB-SPEO, a tool to assess RoB in occupational exposure prevalence studies.•The performance of RoB-SPEO will be tested in the WHO/ILO systematic reviews.