EPA Form EPA-4U24, October 1997

NYC 9/11 Public Portal Document

In the meantime... Whether or not you decide to have the air ducts in your home cleaned, committing Z Educate yourself about duct to a good preventive maintenance cleaning by contacting some or ail of the sources of information listed at program is essential to minimize duct the end of this publication and ask­ contamination. ing questions of potential service providers.

Z If you are replacing your air Are duct materials other than bare conditioning system, make sure that sheet metal ducts more likely to be the unit is the proper size for your contaminated with mold and other needs and that all ducts are sealed biological contaminants? at the joints. A unit that is too big will cycle on and off frequently, resulting in 'W OU may be familiar with air ducts poor moisture removal, particularly in I that are constructed of sheet metal. areas with high humidity. Also make However, many modern residential air sure that your new system is designed duct systems are constructed of fiber­ to manage condensation effectively. glass duct board or sheet metal ducts that are lined on the inside with fiber­ Unresolved Issues of Duct glass duct liner. Since the early 197O’s, Cleaning a significant increase in the use of flexi­ ble duct, which generally is internally Does duct cleaning prevent health lined with plastic or some other type of problems? material, has occurred. The use of insulated duct material has increased he bottom line is: no one knows. due to improved temperature control, There are examples of ducts that energy conservation, and reduced con­ have become badly contaminated with densation. Internal insulation provides a variety of materials that may pose better acoustical (noise) control. risks to your health. The duct system Flexible duct is very low cost. These can serve as a means to distribute products are engineered specifically for these contaminants throughout a home. use in ducts or as ducts themselves, In these cases, duct cleaning may make and are tested in accordance with stan­ sense. However, a light amount of dards established by Underwriters household dust in your air ducts is nor­ Laboratories (UL), the American Society mal. Duct cleaning is not considered to for Testing and Materials (ASTM), and be a necessary part of yearly mainte­ the National Fire Protection Association nance of your heating and cooling sys­ (NFPA). Many insulated duct systems tem, which consists of regular cleaning have operated for years without sup­ of drain pans and heating and cooling porting significant mold growth. Keeping coils, regular filter changes and yearly them reasonably clean and dry is gen­ inspections of heating equipment. erally adequate. However, there is sub­ Research continues in an effort to stantial debate about whether porous evaluate the potential benefits of air insulation materials (e.g., fiberglass) are duct cleaning. more prone to microbial contamination than bare sheet metal ducts. If enough dirt and moisture are permitted to enter the duct system, there may be no signif­ icant difference in the rate or extent of microbial growth in internally lined or bare sheet metal ducts. However,

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