Researchers from the University of Nottingham teamed up with the Nottingham University Hospitals NHS Trust to determine the accuracy of those widely used pulse oximeters based on the color of your skin. Standard pulse oximeters, it turned out, significantly overshot the blood oxygen saturation for the Mixed ethnicity group compared to the White cohort.
https://www.notebookcheck.net/Pulse-oximeter-accuracy-differs-by-skin-color-unreliable-to-measure-true-oxygen-saturation-in-all-COVID-19-pneumonia-cases.596569.0.html