“Wearing a mask for long periods lowers oxygen levels in the wearer.”

“Research presented at the 2021 AAAAI Virtual Annual Meeting found that wearing a mask does not impact oxygen saturation. A total of 223 surveys reviewed showed oxygen saturation (SpO2) ranged between 93-100%, with an average of 98%, for those with asthma and 93-100%, with an average of 98%, for those without asthma. There were no significant differences in measurements when it came to gender, race, type of mask used, or the amount of time masks had been worn.”

“From the results of this study, oxygen saturation level was significantly decreased by the use of both surgical mask and cloth mask compared with control. This finding is consistent with that of [21] which reported a decrease in oxygen saturation levels in surgeons with surgical masks during surgery but contrary to that of [23,46].”

“Tight fitting masks cause inadequate ventilation and increased levels of carbon dioxide (CO2) known as hypercapnia. As CO2 is a known respiratory stimulant, a buildup of exhaled CO2 between the mask and face will cause increased lung ventilation and respiratory activity. Symptoms of hypoxemia such as chest discomfort and tachypnea are also noted in healthcare professionals with prolonged mask use. Prolonged use of N95 and surgical masks causes physical adverse effects such as headaches, difficulty breathing, acne, skin breakdown, rashes, and impaired cognition.”

“Extended SM use may reduce oxygen concentrations in circulation, causing hypoxia, headache, and fatigue. Further research results showed that anesthesiologists wearing SMs for more than 2 h exhibited significantly reduced SpO2 levels and significantly increased respiratory rates, but no change was observed in heart rates.”

“Despite the masks significantly increasing end-expired peri-oral %CO2 and reducing %O2, each ∼0.8−2% during exercise (P < 0.05), our results supported the hypotheses. Specifically, none of these masks reduced sub-maximal or maximal exercise arterial O2 saturation (P = 0.744), but ratings of dyspnea were significantly increased (P = 0.007).”

“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.”

“Do Masks Cause Low Oxygen Levels? Absolutely not. We wear masks all day long in the hospital. The masks are designed to be breathed through and there is no evidence that low oxygen levels occur. There is some evidence, however, that prolonged use of N-95 masks in patients with preexisting lung disease could cause some build-up of carbon dioxide levels in the body. People with preexisting lung problems should discuss mask wearing concerns with their health care providers.”

“Masks definitively don't harm oxygen levels and, right now, they're our best weapon against the spread of COVID-19.”

“The WHO is categorical in their public advice, stating that the prolonged use of face masks does not lead to oxygen deficiency. Doctors and nurses have also responded to the claims with practical demonstrations.”

“While some studies document measurable decreases in oxygen saturation or increases in CO2 with prolonged mask wear (particularly N95 respirators), these changes typically remain within normal physiological ranges and do not constitute clinically significant hypoxemia in healthy individuals. The distinction between statistically significant and clinically significant changes is critical in mask safety research.”