Humidity levels in refrigeration systems can be monitored using sensors such as hygrometers, thermohygrometers, or dew point sensors. These sensors provide real-time data on temperature, relative humidity, and dew point, enabling adjustments to be made to maintain optimal humidity levels. Control strategies can include adjusting humidification or dehumidification rates, modifying air flow patterns, or adjusting cooling coil temperatures. It is essential to integrate humidity monitoring and control into the overall refrigeration system control strategy to ensure efficient and reliable operation.