Air Ducts – Tips to Prevent Contamination

Air ducts in a home or building allow for ventilation and a path for warm or cool air to provide a comfortable indoor environment for families or building occupants. However, if the ducts become dirty and contaminated they may not operate efficiently and could create indoor air quality concerns.

To help prevent air duct contamination, the U.S. Environmental Protection Agency (EPA) provides the following tips:

• Use the highest efficiency air filter recommended by the manufacturer of the heating and cooling system.
• Change filters regularly.
• If filters become clogged, change them more frequently.
• Be sure there are no missing filters and that air cannot bypass filters through gaps around the filter holder.
• When having the heating and cooling system maintained or checked for other reasons, be sure to ask the service provider to clean cooling coils and drain pans.
• During construction or renovation work that produces dust indoors, seal off supply and return registers and do not operate the heating and cooling system until after cleaning up the dust.
• Remove dust and vacuum regularly using a high efficiency vacuum (HEPA) cleaner or the highest efficiency filter bags the vacuum cleaner can take.
• If the heating system includes in-duct humidification equipment, be sure to operate and maintain the humidifier strictly as recommended by the manufacturer.

To prevent ducts from becoming wet and supporting microbial growth, the EPA recommends:
• Promptly and properly repair any leaks or water damage.
• Pay particular attention to cooling coils, which are designed to remove water from the air and can be a major source of moisture contamination of the system that can lead to mold growth. Make sure the condensate pan drains properly.
• Make sure ducts are properly sealed and insulated in all non-air-conditioned spaces (e.g., attics and crawl spaces).
• If replacing an air conditioning system, be sure that the unit is the proper size and that all ducts are sealed at the joints.