Blood oxygen (SpO2)

• Wrist and ring sensors may be less steady than fingertip ones, especially when loose or when you are moving.
• A 2025 systematic review (Clinical Nursing Research) looks at whether skin pigmentation affects detection of low oxygen.
• A 2026 Journal of Biomedical Optics paper looks at the cause of melanin-associated bias and how to remedy it.

Source: Clinical Nursing Research, 2025, Journal of Biomedical Optics, 2026

• Clinicians use pulse oximetry, together with symptoms, to check oxygen in people who are unwell or being monitored.
• Check whether your overnight readings are steady for you.
• One odd reading is common when the fit is poor; repeated low readings, or a fall with breathlessness, are worth mentioning to a GP.
• Some people, for example with long-term lung conditions, have a lower usual level.

Source: NHS England

• Act on symptoms rather than the wearable figure.
• NHS England leaflets advised contacting 111 or a GP if you feel more breathless over time.

Source: NHS England

Is the SpO2 on my watch a medical reading?

No. Treat it as an estimate and act on symptoms; a consumer wearable is not a substitute for a clinical oximeter.

Can skin tone affect pulse oximeter readings?

Yes. A 2020 NEJM research letter reported racial bias in pulse oximetry, and later reviews look at the effect of skin pigmentation.

What if my reading is low but I feel well?

Re-check with good contact and warm, still hands. If low readings recur, or you have symptoms such as breathlessness, speak to a GP or NHS 111.

• Racial Bias in Pulse Oximetry Measurement, New England Journal of Medicine, 2020 (Sjoding et al.)
• Do Differences in Skin Pigmentation Affect Detection of Hypoxemia by Pulse Oximetry - A Systematic Review of the Literature, Clinical Nursing Research, 2025
• Cause, effect, and remediation of melanin-associated bias in pulse oximetry, Journal of Biomedical Optics, 2026
• COVID-19 guidance note - COVID Oximetry @home, NHS England