Although modern technology has made significant advances in air filters over the past decade, a fractional amount of dust still finds its way past heating and cooling filters and into your homes ducts. As this dust accumulates throughout your home, it creates the perfect environment for the growth of mold, mites and harmful bacteria. To check your ducts for dust buildup, pull off several supply and return registers and see how much dust has accumulated in the system. If you choose to clean your system, your best option is to contact a professional duct cleaner.
Although duct cleaning has little effect on the actual air quality, it will eliminate a house-wide breeding ground for harmful bacteria and mold in addition to helping your heating and cooling system operate more efficiently. If you are installing a new system, you should consider cleaning the ducts at the same time. New systems are often more powerful than old systems and can stir up dust that is sitting in the existing ductwork.