I've got pah.
The other evening i went upstairs to bed and was somewhat out of breath as usual. For the first time after walking upstairs i used my oximeter. It was 49. Put my oxygen on and over a few minutes it was back at 90.
The next day i had a bath, not on oxygen and requiring some movement. I was slightly out of breath and my oxygen was 68.
These seem quite low values to me and there seems to be little connection between sob and oxygen level