Are there any health benefits that come from Air Duct system cleaning?

Heating, ventilation, and air conditioning (HVAC) systems have been shown to act as a collection source for a variety of contaminants that have the potential to affect health, such as mold, fungi, bacteria, and very small particles of dust.  The removal of such contaminants from the HVAC system and home should be considered as one component in an overall plan to improve indoor air quality.