I am an EMR in California and provide (emergency) medical care relatively frequently. "To self-assess the seriousness of breathing issues I intend to make us o

I am an EMR in California and provide (emergency) medical care relatively frequently. "To self-assess the seriousness of breathing issues I intend to make us of a pulsoxymeter." I like the idea of owning a pulse oximeter and have them in all of my first aid kits. However, I think of them as providing immediate information about an acute breathing problem. Your SpO2 should be around 98 always. If you go below 95, something is really wrong and requires immediate attention. You will be displaying signs of breathing difficulty and you're not going to see if it lasts 24 or 48 hours. If you are not tremendously affected by a cold/flu/coronavirus, I would expect you to have a ~98 SpO2 throughout, even if you feel terrible and perhaps feel your breathing is a bit labored. " ... below 80% immediately ..." Just to put this in perspective, all else being equal, you're not going to be coherent or functional in any way below 80%. I would personally call 911 if I saw an otherwise normal person below 90 and I would be very concerned if I saw readings below 95 - especially if the trendline was down ...