- Q Why Clean Air Ducts? A Your heating and cooling system consists of the ducts and air handling system (heater, air conditioning coil, condenser, blower, etc.). When the house was built, this system often becomes contaminated with insects, rodents, drywall dust, sawdust, nails, boards, sand, and other construction debris, but is never cleaned. As the house is lived in, the system becomes further contaminated with pollens, pet hairs and pet dander, mold, fibers from clothing and carpets, mold, bacteria and other microbes. They all stick to the dust in your heating and cooling system. When your blowers are on, these allergens and contaminants shoot out into the air you breathe, and into your lungs! This aggravates allergies, asthma, and other respiratory conditions. A joint study by the EPA and the National Air Duct Cleaning Association (NADCA) revealed that proper cleaning of the ducts and air handling system reduces airborne particles put out by the system by 95% - 98%. These contaminants can also clog your air conditioning coil, reducing the efficiency of the system. The system has to run longer to deliver the same amount of heat or cooling, so your utility bills are higher. The EPA has found that a build-up of only .042 inches of dirt on a heating or cooling coil can decrease its efficiency by 21%. A 1987 ASHRAE study concluded that heating and cooling systems that are kept clean cost 10% - 25% less to operate. This can easily translate to a $400-$500 reduction in your gas and electric bill each year! And dirty systems not only increase utility bills, the strain on the system can take years off of the useful life of the system.