Anbar, ArielBuick, RogerGordon, GwynethJohnson, AleishaKendall, BrianLyons, TimothyOstrander, ChadlinPlanavsky, NoahReinhard, ChristopherStueken, Eva2023-10-302023-10-302023-04-07https://doi.org/10.1126/sciadv.abq3736http://hdl.handle.net/10012/20073Copyright © 2023 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). https://creativecommons.org/licenses/by-nc/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.Many lines of inorganic geochemical evidence suggest transient “whiffs” of environmental oxygenation before the Great Oxidation Event (GOE). Slotznick et al. assert that analyses of paleoredox proxies in the Mount McRae Shale, Western Australia, were misinterpreted and hence that environmental O2 levels were persistently negligible before the GOE. We find these arguments logically flawed and factually incomplete.enArticle