The primary chemical agents used in air duct cleaning processes are biocides, surfactants, degreasers, and detergents. The best duct systems are made of galvanized sheet with an outer insulation layer and a vapor retarder. This type of duct is ideal for cleaning due to its smooth surfaces and zinc coating, which acts as a fungicide to prevent the growth of mold and mildew. From an energy conservation and indoor air quality standpoint, controlling the source of pollution is the most effective way to keep duct systems clean and trouble-free.
It is essential to change filters regularly and to have the air conditioning system checked by an HVAC contractor at least once a year. During the cleaning process, it is important to vacuum the heat exchanger, clean the coils, and make sure that the drip tray is clean and drains properly. An air duct cleaning operation may also include the application of chemical biocides to the non-porous surfaces of the air conditioning system. These chemicals can be disinfectants, disinfectants, or deodorants. Sealants should never be used on wet lining of ducts, to cover actively growing mold, or to cover duct debris, and should only be applied after cleaning in accordance with NADCA guidelines or other appropriate regulations. As long as cleaning is done correctly, there is no evidence that it could be harmful.
Problems caused by dirt in air ducts are not usually solved by duct cleaning methods. The shortcoming of the FIU study was that the readings were only taken immediately before cleaning, during cleaning, and two days after cleaning. Compressed air sweeping method is used in which compressed air is introduced into the duct to dislodge dirt and debris, and is transported downstream through the duct and exits the system by vacuum collection equipment. Studies also suggest that cleaning techniques that agitate duct systems, particularly fiberglass ducts, may pose a greater problem by detaching fiberglass particles from the duct plate. If you think that cleaning the ducts might be a good idea for your home but you're not sure, talk to a professional.
The EPA and most experts generally do not recommend using biocides, air fresheners, or cleaning agents in filters or duct systems until they have been specifically approved by the EPA. Whether or not you decide to clean your home's air ducts, it's essential to commit to a good preventive maintenance program to minimize duct contamination. Air duct cleaning service providers may tell you that they need to apply a chemical biocide to the inside of the ducts to kill bacteria (germs) and fungi (mold) and prevent future biological growth. These products are specifically designed for use in ducts or as ducts themselves, and are tested according to standards established by Underwriters Laboratories (UL), the American Society for Testing and Materials (ASTM), and the National Fire Protection Association (NFPA). If no one in your home has allergies or unexplained symptoms or illnesses and if, after a visual inspection of the inside of the ducts, you see no evidence that they are contaminated with large deposits of dust or mold (there is no musty smell or visible mold growth), it is probably not necessary to clean them. Knowledge about cleaning air ducts is still in its early stages, so no general recommendation can be offered as to whether you should clean your home's air ducts.
Consider using these products only after you have mechanically cleaned the ducts by shaking and vacuuming them.
