O2 sensors are sensitive to changes in atmospheric pressure and moisture, the analysis of the same gas will show you:

Oxygen sensors are designed to measure the concentration of oxygen in a gas mixture, such as in enriched air nitrox. These sensors can indeed be affected by variations in atmospheric pressure and humidity. Changes in atmospheric pressure can alter the density of the gas, impacting how the sensor perceives the mole fraction of oxygen present. Similarly, moisture in the gas can interfere with the sensor's ability to accurately detect and measure oxygen levels.

When faced with different conditions, the analysis of the same gas can yield slightly different readings. The presence of moisture can lead to variations in the sensor's output due to condensation effects or changes in the electrical properties of the sensing medium. Additionally, if atmospheric pressure changes, the sensor may register a different effective concentration of oxygen. Therefore, in practice, even a small change in these environmental conditions could result in the sensor displaying a reading that is not constant but rather slightly different from previous measurements. This effect is crucial for divers to understand, as it underscores the importance of calibrating equipment under similar environmental conditions to ensure accuracy in gas mixtures used for diving.