Here is some information from NADCA (National Air Duct Cleaners Assoc.)
Why Clean Air Ducts?
Answer: Because they get dirty!
In addition to normal accumulations of dust and dirt found in all homes with air ducts, there are several other factors that can increase the need for regular HVAC system cleaning:
pets
occupants with allergies or asthma
cigarette or cigar smoke
water contamination or damage to the home or HVAC system
home renovation or remodeling projects
Some occupants are more sensitive to these contaminants than others. Allergy and asthma sufferers, as well as young children and the elderly tend to be more susceptible to the types of poor indoor air quality that air duct cleaning can help address.
Top Benefits of HVAC Cleaning
NADCA’s rule of thumb for consumers is that “if your air ducts look dirty, they probably are,” and that dirty HVAC systems should be inspected by a reputable, certified HVAC professional.
Indoor Air Quality
Indoor air quality is one concern that homeowners have when they decide to investigate air duct cleaning. Your heating and cooling system is the lungs of your home. The system takes air in and breathes air out.
