I myself do have issues breathing through a bandana and a surgical or medical mask. However, I am also in fairly good CF shape lower 60’s / high 50’s PFTs, with running miles a week and swimming many laps a wekk in the pool, well, that was until Covid hit!
I tried this same test on myself, 3 different styles of masks but for only 5 minutes a crack while resting in an air conditioned room. My results were like yours, it didn’t change.
Now, we did this same test on a non-CF male and he wore a mask for an hour while performing work activities out on our assembly plant foor that was not atomsphere controlled. His pulse OX was tested before and after teh hour. His pulse OX level was significantly lower after the hour of completing typical work tasks. I believe it was in the mid to high 80’s. From this it seems that it takes awhile for your body to adjust to the lower oxygen levels and process through the oxygen that the system still has and will eventaully over time and displaced by more carbon dioxide? I’m not sure of about the body’s exchange rate of oxygen to carbon dioxide and vice versa. SAo again I’m not 100% sure on that, this is just my own theory.
We also did another similar test. We took a 4-gas air monitor, one of the gases it measures is oxygen for proper concentrations when entering a Confined Space per OSHA regulations. OSHA regulation states the ambient oxygen concentration must not go below 19.5% oxygen, if this happens you MUST BY LAW exit the confined space immediately as this is an IDLH (immediately dangerous to life and health) atmosphere, as a benchmark normal “air” has 20.8% oxygen concentration. So, a fellow co-worker (and in-shape female) and I ran this experiment; we each did a 1-minute step test on set of stairs in approximately 80 degree, semi-humid, non-air conditioned atmosphere and we measured the oxygen concentration inside the mask at the corner of our mouth. Both of us wore a different style of mask for each test and we each tested 3 different styles of masks. With each mask it didn’t matter what the style of mask was the oxygen concentration inside the mask dropped down to approximately 18% oxygen (give or take) concentartionin in under 10 seconds. During the testing of the 3 different styles of masks the lowest we saw was a 16.5% oxygen concentration and the average was approximately 17.5% oxygen concentration. Now, remember what OSHA says about an atmosphere below 19.5% oxygen concentration???
With this being said what is going to be the long-term side effects of wearing a mask 8 hrs., 10 hrs. or 12-hours a day over a course of weeks, months and maybe a year while exerting phycial activity, in a non-controlled, non-air conditioned atmosphere? What would the long-term effects be on a CF patient? What about an older, out of shape individual? I guess this all remains yet to be seen, but I’m afraid we will find out probably sooner than later!
By the way, I have been in the safety field since 1998 and worked with industrial hygiene monitoring programs, reviews and monitoring the past 16 years.
Just my experience and information collected from our self-tests.