A pulmonologist hears complaints from a few of his patients that they feel tired and fatigued after wearing an N95 mask for hours at a time and believe that their blood oxygen levels are lowered. The doctor, having to wear a mask all day himself, does not believe this is true, but decides to test it.
He finds a group of 50 volunteers for his study. He assigns 25 of them to wear an N95 mask while walking at a brisk pace of 5km/hr on a treadmill for 30 minutes. The other 25 will be unmasked while performing the same exercise.
Following the study, he finds that the average oxygen saturation level of the masked group is 98.1%, while the average oxygen saturation level of the unmasked group is 98.3%.