Archive:
https://archive.vn/6Rjo7
Meat of the matter:
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Normal blood-oxygen levels are around 97%, Moss said, and it becomes worrisome when the numbers drop below 90%. At levels below 90%, the brain may not get sufficient oxygen, and patients might start experiencing confusion, lethargy or other mental disruptions. As levels drop into the low 80s or below, the danger of damage to vital organs rises.
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However, patients may not feel in as dire straits as they are. A lot of coronavirus patients show up at the hospital with oxygen saturations in the low 80s but look fairly comfortable and alert, said Dr. Astha Chichra, a critical care physician at Yale School of Medicine. They might be slightly short of breath, but not in proportion to the lack of oxygen they're receiving.
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View attachment 1253560
TLDR; Get yourself one of these bad boys off Amazon for $20 ("oximeter"), if rich feel feel to pay more for medical grade device or splurge on one of these new fancier smart watches with "SpO2 sensor".
Use it daily and if your blood oxygen level drops below 90, try to get to hospital, start logging the oximeter readings in addition to other symptoms and keep pestering them daily, if you can't.