Oximetry is a test of how much oxygen is carried by red blood cells, used to estimate how well a person’s lungs are working. A small device known as a pulse oximeter is placed on a fingertip. The device emits red and infra-red light; oxygenated blood absorbs more infra-red and less red light than de-oxygenated blood. The skin pigment melanin, which gives skin its darker tones, also absorbs light in these same wavelengths. As a result, pulse oximeters are less accurate for people with darker skin tones, and low oxygen levels may be detected late in people of color. In 2024, the FDA issued new guidance to manufacturers to ensure devices were tested in a wide range of skin tones in order to avoid this racial bias.
