[kumarvvr]

Whoa, I sometimes get SpO2 around 91 - 94 and I chalk it up to calibration error on cheap SpO2 devices (The ones that clip on to the hand, cost about 20 USD). Have been tested twice per employer requirements and was never positive though.

[rolleiflex]

The cheap SPO2 devices are calibrated on fair skin. If you have a darker complexion there is a known measurement error. If you are at 91% and feeling fine you are probably fine. Your body has a better SPO2 sensor than anything man-made.

[kumarvvr]

Damn, I am brown and I guess I have to take that as a 3 - 5% error?

[rolleiflex]

That is correct. See here: https://pubmed.ncbi.nlm.nih.gov/18048893/