Effects of Wearing Facemasks During Brisk Walks: A COVID-19 Dilemma

Bar-On, Ophir; Gendler, Yulia; Stafler, Patrick; Levine, Hagit; Steuer, Guy; Shmueli, Einat; Prais, Dario; Mei-Zahav, Meir

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 +4.5 ± 2.4 versus +2.9 ± 2.3, P = .004; brisk walk EtCO2 change +8.4 ± 3.0 versus +6.2 ± 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 % ± 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.