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. 2022 Jan 19;62(5):600–606. doi: 10.1016/j.jemermed.2021.11.021

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Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

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Median ETCO₂ values and dyspnea scores with medical mask and medical mask plus FFP2 respirator at 2 time points. ETCO₂ = end-tidal carbon dioxide; FFP2 = type II filtering facepiece respirator; MM = medical mask; T = time point; VAS = visual analog scale.