Covid 19 Oximetry@Home services have been commissioned nationally. This allows higher risk patients with mild Covid 19 symptoms to remain at home, being supplied with a Pulse Oximeter to measure their oxygen saturation (SpO2) two to three times daily for two weeks. Patients record their readings manually or electronically which are monitored by a clinical team. Clinical decisions, using an algorithm, are based on SpO2 readings in a narrow range with 1-2 point changes potentially affecting care. In this article we discuss the problem that multiple factors affect SpO2 readings, and that some ‘normal’ individuals will have ‘low normal’ scores at the threshold of clinical management, without any known respiratory problem. We discuss the potential magnitude of this problem based on the associated literature and consider how this will impact on the use of the Oximetry@home services, potentially partially confounding their purpose; to reduce face to face medical care.