Why do I need air duct cleaning?
Dust consisting of dirt, pollen, germs, fibers, mold spores, hair and more gets drawn into your air duct system. About 95% of these particles will pass through a normal air filter and back into the room air, or it will accumulate on the fan blades, grills, or in the ductwork.
This buildup can reduce air duct air flow up to 40%. It is also a breeding ground for bacteria and molds that can cause allergic reactions in many people and is also a source of musty odors. Remember — most problems with indoor air quality are invisible and odorless! Air duct cleaning should be performed every three years.
Indoor Air Quality Checklist