The effects of wearing facemasks on oxygenation and ventilation at rest and during physical activity

Abstract

Background Facemasks are recommended to reduce the spread of SARS-CoV-2, but concern about inadequate gas exchange is an often cited reason for non-compliance. Research question Among adult volunteers, do either cloth masks or surgical masks impair oxygenation or ventilation either at rest or during physical activity? Study design and methods With IRB approval and informed consent, we measured heart rate (HR), transcutaneous carbon dioxide (CO2) tension and oxygen levels (SpO2) at the conclusion of six 10-minute phases: sitting quietly and walking briskly without a mask, sitting quietly and walking briskly while wearing a cloth mask, and sitting quietly and walking briskly while wearing a surgical mask. Brisk walking required at least a 10bpm increase in heart rate. Occurrences of hypoxemia (decrease in SpO2 of ≥3% from baseline to a value of ≤94%) and hypercarbia (increase in CO2 tension of ≥5 mmHg from baseline to a value of ≥46 mmHg) in individual subjects were collected. Wilcoxon signed-rank was used for pairwise comparisons among values for the whole cohort (e.g. walking without a mask versus walking with a cloth mask). Results Among 50 adult volunteers (median age 33 years; 32% with a co-morbidity), there were no episodes of hypoxemia or hypercarbia (0%; 95% confidence interval 0–1.9%). In paired comparisons, there were no statistically significant differences in either CO2 or SpO2 between baseline measurements without a mask and those while wearing either kind of mask mask, both at rest and after walking briskly for ten minutes. Interpretation The risk of pathologic gas exchange impairment with cloth masks and surgical masks is near-zero in the general adult population.

Effect of a Warm-Up Protocol with and without Facemask-Use against COVID-19 on Cognitive Function: A Pilot, Randomized Counterbalanced, Cross-Sectional Study

“…For example, in a sample of 50 adults (one-third of which has an underlying co-morbidity), no episodes of hypoxemia or hypercarbia occurred. No differences in CO 2 or oxygen saturation (SpO 2 ) could be detected between baseline values and those measured while exercising (walking briskly for ten minutes) when wearing a mask [ 28 ].…”

“…Furthermore, we found that both groups (EXP and CON) showed different results for RPE, which was not in line with the scholarly literature. For example, Morris et al [ 28 ] showed that physiological strain or thermal discomfort did not differ between prolonged facemask-use and the control condition. Only perceived dyspnea was found to significantly differ between the two conditions.…”

COVID-19 false dichotomies and a comprehensive review of the evidence regarding public health, COVID-19 symptomatology, SARS-CoV-2 transmission, mask wearing, and reinfection

“…However, claims pertaining to decreased oxygen saturation are unfounded. Recent studies assessing medical masks and cloth face coverings in the general adult population have not demonstrated major physiologic changes related to gas exchange [454,455,[556][557][558][559][560][561].…”

Mit dieser Erhebung sind die Beeinträchtigungen durch das Masketragen bei Kindern nicht objektivierbar

“…Auf S. 362 wird die Frage CO 2 -Retention unter der Maske aufgegriffen. Es ist richtig, dass es dazu keine Studien bei Kindern gibt, wohl aber bei Erwachsenen, die keine Hinweise auf CO 2 -Retention zeigen [ 2 ]. In der Diskussion wird auf eine mögliche pathophysiologische Hypothese, warum bei Kindern diese Effekte anders, sogar schwerwiegender sein sollten, nicht eingegangen.…”