Effects of wearing facemasks during brisk walks: A COVID-19 dilemma

Background: During the Coronavirus disease 2019 (COVID-19) pandemic, wearing facemasks became obligatory worldwide. Objectives: The objective of this study was to evaluate the effects of facemasks on gas exchange. Methods: Healthy adults were assessed at rest and during slow and brisk 5-minute walks, with and without masks. We monitored O₂ saturation, end-tidal carbon dioxide (EtCO₂), and heart and respiratory rates. Participants graded their subjective difficulty and completed individual sensations questionnaires. Results: Twenty-one participants with a median age of 38 years (range, 29–57 years) were recruited. At rest, all vital signs remained normal, without and with masks. However, during slow and brisk walks, EtCO₂ increased; the rise was significantly higher while wearing masks: slow walk, mean EtCO₂ (mmHg) change 14.5 6 2.4 versus 12.9 6 2.3, P = .004; brisk walk EtCO₂ change 18.4 6 3.0 versus 16.2 6 4.0, P = .009, with and without masks, respectively. Wearing masks was also associated with higher proportions of participant hypercarbia (EtCO₂ range, 46–49 mmHg) compared with walking without masks, though this was only partially significant. Mean O₂-saturation remained stable (98%) while walking without masks but decreased by 1.2 % 6 2.2 while walking briskly with a mask (P = .01). Mild desaturation (O₂ range, 93% to 96%) was noted during brisk walks among 43% of participants with masks, compared with only 14% without masks (P = .08). Borg’s scale significantly increased while walking with a mask, for both slow and brisk walks (P < .001). Sensations of difficulty breathing and shortness of breath were more common while walking with masks. Conclusion: While important to prevent viral spread, wearing facemasks during brisk 5-minute walks might be associated with mild hypercarbia and desaturation. The clinical significance of these minor gas exchange abnormalities is unclear and should be further investigated.