Depending on the level of air cleaning desired, the IQAir system can be operated as frequently as needed. For general air cleaning purposes, the system should filter the room air volume at least twice every hour on the set fan speed in order to achieve a significant air quality improvement. If the intensity of the pollution source is high or a high degree of purification is needed, more air changes may become necessary. More air changes may be achieved by selecting a higher fan speed and/or by running the room air cleaner more frequently. It is the customer's discretion as to how often they actually operate their IQAir system. All IQAir room air cleaners can be run 24 hours a day, if needed, without harm to the system. For more information, please refer to the HealthPro User Manual, chapter 4.3, Fan Speed & Air Delivery.