Do I need to re-calibrate the DS1923 after a certain amount of time?

The devices were calibrated before they left the factory and do not require re-calibration. Users may determine the offset of the devices in a controlled environment by comparing the data retrieved from the devices to known temperature. Our humidity logger measures %RH using a standard humidity sensor. Therefore, they might need to be re-calibrated periodically depending on the environment it is operating in since absorption of contaminants can degrade its accuracy.