The general procedure for collection and analysis of air samples of Cr(VI) is described in OSHA method no. ID-103 (11.1.). Briefly, the Cr(VI) sample is collected on a 37-mm polyvinyl chloride (PVC) filter and submitted to the laboratory for analysis. Any Cr(VI) on the filter is extracted with a hot sodium carbonate (Na2CO3) / sodium bicarbonate (NaHCO3) buffer solution. The extract is then analyzed for Cr(VI) by differential pulse polarography (DPP) using a dropping mercury electrode. The analytical method has been validated using soluble and insoluble chromate compounds and a selected time weighted average (TWA) concentration range of about 0.005 to 0.01 mg/m3 as Cr(VI) or 0.009 to 0.02 mg/m3 as CrO3 (840-L air sample). The TWA concentration selected for evaluation was considered a very low level at the time of the evaluation. When this method was first developed, the OSHA TWA permissible exposure limit (PEL) was 0.1 mg/m3 as CrO3 (11.2.). The PEL at the time of this revision is 0.1 mg/m3 as a ceiling determination.