Air duct cleaning implies cleaning of the conduits in the HVAC (Heating, Ventilation and Air Conditioning) system. It includes cleaning of supply and return air ducts, registers, grilles, diffusers, heat exchangers, heating and cooling coils, condensate drain pans, fan motor, fan housing, and air handling unit housing. These ducts gather particles of dust, pollen, and other debris. They can also become a hub of microbiological growth (e.g., mold) with the presence of moisture. Spores from such growth can get released into your living space and cause respiratory irregularities, autoimmune disorders, and some environmental allergies.
I had my ducts somewhat cleaned December 22, 2014. The hose of the machine the technitian used did not fit in some of my vents, therefore, he did not clean them. But I still paid $428.00 for the service. I will be calling the company on Monday, and kindly ask them to come back and clean the ducts they did not as they did not fullfill their part of the service.
Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts. This is because much of the dirt in air ducts adheres to duct surfaces and does not necessarily enter the living space. It is important to keep in mind that dirty air ducts are only one of many possible sources of particles that are present in homes. Pollutants that enter the home both from outdoors and indoor activities such as cooking, cleaning, smoking, or just moving around can cause greater exposure to contaminants than dirty air ducts. Moreover, there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to your health.