Indoor air quality (IAQ) in HVAC systems is a measure of the air quality within a building or home. It is determined by the amount of pollutants, such as dust, pollen, mold, and other allergens, that are present in the air. Poor IAQ can lead to health problems, such as allergies, asthma, and other respiratory illnesses. To ensure good IAQ, HVAC systems should be regularly maintained and serviced to ensure that the air filters are clean and that the system is operating efficiently. Additionally, proper ventilation should be provided to allow for fresh air to enter the building and to reduce the amount of pollutants that are present in the air.