Melymuk et al. J Environ Expo Assess 2022;1:15 DOI: 10.20517/jeea.2022.12 Journal of Environmental Exposure Assessment © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, sharing, adaptation, distribution and reproduction in any medium or format, for any purpose, even commercially, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. www.oaepublish.comjeea Open Access Research Article Questioning the appropriateness of sieving for processing indoor settled dust samples Lisa Melymuk, Simona Rozárka Jílková, Michal Kolář, Petra Svobodová, Branislav Vrana, Klára Hilscherová RECETOX, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137, Czech Republic. Correspondence to: Prof. Lisa Melymuk, RECETOX, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137, Czech Republic. E-mail: lisa.melymuk@recetox.muni.cz How to cite this article: Melymuk L, Jílková SR, Kolář M, Svobodová P, Vrana B, Hilscherová K. Questioning the appropriateness of sieving for processing indoor settled dust samples. J Environ Expo Assess 2022;1:15. https://dx.doi.org/10.20517/jeea.2022.12 Received: 12 May 2022 First Decision: 2 Jun 2022 Revised: 8 Jun 2022 Accepted: 13 Jun 2022 Published: 15 Jun 2022 Academic Editor: Stuart Harrad Copy Editor: Jia-Xin Zhang Production Editor: Jia-Xin Zhang Abstract Dust is a widely-used matrix for estimating human exposure to chemicals or as a screening tool for the identification of indoor chemicals of concern. As dust sampling became more common in exposure assessment, techniques used in processing soil have been adapted to dust samples, and separation of dust particles by sieving is common practice. However, there are no defined pore sizes, which results in inconsistent or difficult data interpretation and exposure estimates. Moreover, dust consists of more particle types than soil, particularly fibers, which behave differently during the sieving process. In this study, composite samples from seven microenvironments (homes, apartments, kindergartens, schools, public spaces, offices, and cars) were used to investigate the impact of the separation of dust by sieving on the observed chemical distributions. Dust was sieved to four particle size fractions (1-2 mm, 0.5-1 mm, 0.25-0.5 mm, and < 0.25 mm) and each fraction was analyzed for organic carbon content and polycyclic aromatic hydrocarbons (PAHs), and images of dust samples were taken by optical microscope. We identified irregular distributions across size fractions for carbon and PAHs as well as for fibrous particles. Based on the combination of chemical analyses and microscopy, we recommend careful consideration of pre-processing of dust samples to limit bias in dust exposure assessments, and sieving should be used only when necessary. Keywords: Indoor dust, size fractions, dust exposure, polycyclic aromatic hydrocarbons, dust composition