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. 2021 Sep 10;12:710573. doi: 10.3389/fphys.2021.710573

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Copyright © 2021 Zhang, Li, Zheng, Cai, Yang, Zhang, Yilifate, Zheng, Lin, Liang, Guo and Ou.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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Fit comparison of mask-on and mask-off condition. (A1) Mask-off condition. (A2) Fit test in mask-off condition. (B1) Mask-on condition. (B2) Fit test in mask-on condition.