This video shows Maitiu O Tuathail putting six masks on his face while recording his blood oxygen saturation levels.
As he puts on mask after mask, the meter shows a steady, and healthy, 98-99 percent.
O Tuathail posted the video on Twitter to address the misconception that face masks negatively affect oxygen levels.
He said he was being asked this regularly by patients, who were citing misinformation they had found on social media.
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