If your home, office, or commercial space has air ducts, you may have wondered how often they should be cleaned. Researching the topic will bring up information saying the procedure should be done every few years. However, many of these results have been written by air duct cleaning companies trying to sell their services. Read on for a balanced take on answering this not-so-simple question.
Debunking Several Air Duct Cleaning Myths
You may be surprised to learn that decades of research have not supported common beliefs about air duct cleaning. A 2010 review 
on duct cleaning studies did not find that the practice benefits indoor air quality, HVAC performance, occupant health, or energy savings. The U.S. EPA and Division of Occupational Health and Safety (DOHS) clear up several air duct cleaning myths with the following facts:
- Contrary to popular belief, air duct cleaning should not be part of routine maintenance.
- The EPA neither sets duct cleaning standards nor certifies duct cleaning companies.
- Dusty air vents are normal, caused by dusty air being pulled through the grates. They do not indicate that your ducts are contaminated with heavy dust or debris.
- Duct cleaning has never been shown to prevent health problems.
- While proper air duct cleaning has not been shown to be harmful to human health, improper air duct cleaning can cause indoor air problems. Inadequate cleaning can simply stir up dirt and microbes and release them into the home. According to the study cited above , post-cleaning levels of contaminants were often higher than pre-cleaning levels.
What About UV Air Duct Disinfection?
While air duct cleaning may not prevent health problems, there is evidence to support UV duct disinfection as a means to help prevent disease. One study conducted at office buildings in Montreal exposed certain workers to ductwork equipped with UV systems. Those individuals experienced less headaches, coughs, congestion, and respiratory issues when UV air duct disinfection was running.
On surfaces within these UV-equipped ventilation systems, there was a 99% reduction of microbial and endotoxin concentrations. Another study conducted in homes of mold-sensitized, allergic children found that UV-C air duct systems produced “significant alleviation of several asthma outcomes.”
The American Society of Heating, Refrigerating and Air-Conditioning Engineers states:
The effectiveness of a UV-C system to inactivate microorganisms in the air and/or on surfaces has been amply demonstrated; the best results were obtained for the long-term irradiation of downstream coil surfaces.
—ASHRAE, in its position document
ASHRAE cites the findings of a 2017 study confirming this evidence, while also highlighting reduced maintenance cost and energy use. The U.S. EPA and Rensselaer Polytechnic Institute have found our AeroLogic® Air Duct Disinfection models to be efficient, safe, and effective in reducing contaminants in air duct systems.
When is Air Duct Cleaning Really Needed?
Since conditions in every home or building are different, making a general statement for or against air duct cleaning is impossible. While the practice is not necessary in most cases (and may even be more harmful), the EPA and industrial hygienists agree it is proper in the following circumstances:
- Permanent or persistent water damage appears in your air ducts.
- Slime or microbial growth is present in ducts.
- There is substantial, visible mold growth inside your ducts or on other components of your heating and cooling system.
- Debris build up in your ducts that restrict airflow.
- Ducts are clogged with excessive amounts of dust and debris that are coming out of your air vents.
- Offensive odors are coming from ductwork or HVAC components.
- Your ducts are infested with rodents or insects.
How to Prevent Air Duct Contamination
Whether or not you decide to have your air ducts cleaned, good preventive maintenance practices are essential to minimize duct contamination. Follow these recommendations from the EPA and DOHS and avoid the potential hazards and cost of air duct cleaning:
- Use the highest efficiency air filter recommended by the manufacturer of your heating and cooling system.
- Follow manufacturer schedules for changing filters. If your filters become clogged, change them more frequently.
- If renovating, seal ductwork to prevent construction dust and debris from entering you air ducts.
- Maintain good housekeeping in occupied spaces to help prevent excessive debris from entering your ducts. Use a high efficiency, HEPA filter vacuum or the highest efficiency filter bags your vacuum cleaner can take.
- If your heating system includes in-duct humidification equipment, operate and maintain the humidifier as the manufacturer recommends.
- Prevent moisture due to condensation from entering your HVAC system, by making sure ducts are properly sealed and insulated in all non-air-conditioned spaces (like attics and crawl spaces).
- Ensure that air vents are located away from any sources of contamination.
- Consider routine inspections of your ducts. The National Air Duct Cleaning Association (NADCA)’s standard, “Assessment, Cleaning and Restoration of HVAC Systems ACR 2013,” recommends that HVAC systems be visually inspected for cleanliness at regular intervals, depending on building use. For healthcare facilities, the standard recommends annual inspections of air handling units and supply/return ductwork.
- When having your heating and cooling system maintained or checked, ask the service provider to clean cooling coils and drain pans.
In their technology evaluation report , the U.S. EPA documents the efficiency and safety of the AeroLogic® Air Duct Disinfection System in reducing the presence of microorganisms within air duct systems.
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Made in the USA from US and imported parts, AeroLogic® UV Air Duct Disinfection models from Atlantic Ultraviolet Corporation® are constructed of the highest quality materials and use germicidal UV-C lamps to purify HVAC Ducts. In addition to the superior features listed above, they have many optional accessories available, making them flexible ultraviolet air duct disinfection systems for any application.
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