After enduring years of advertising claims about the effectiveness of air duct cleaning - some of them outrageous and almost all of them unfounded in actual science - and after seeing it grow from a fledgling small business opportunity to a multi-million dollar industry, the Environmental Protection Agency (EPA) became interested in 1997. The EPA decided to conduct a study on the effectiveness of air duct cleaning. The National Air Duct Cleaners Association (NADCA) had the opportunity to get involved in the "Pilot Field Study to Evaluate the Effectiveness of Cleaning Residential Heating and Air-conditioning systems and the Impact on Indoor Air Quality and System Performance."
An article about that study was published in the April 1999 issue of Better Homes and Gardens. Titled "Duct Cleaning: the Inside Dirt," it stated that, "... a recent study by the Environmental Protection Agency (EPA) found little reason to recommend duct cleaning. The Agency says there is no proof that having ducts cleaned will improve the quality of the air in your home, and that duct cleaning has never been shown to improve health problems.'
INDUSTRY'S DEFENSE
That statement is a blow to duct cleaners everywhere - or would be if it were true. The actual project summary as released by the EPA states, "The results ... have demonstrated that mechanical cleaning methods … effectively removed particulate and fibrous contamination." It went on to say that duct cleaning's effects on bacteria, molds, and fungi "could not be fully evaluated because chemical biocides were not used in this study."
The EPA summary also admits that some of its conclusions were invalidated because some results may have been attributable to minor repairs of leaks in the ducts and loose floor boots of supply registers" made during the cleaning. According to Bob Allen, president of Video-Aire International, Fort Worth, TX, the impact of the positive result was weakened by non-compliance with the scientific method. Plans for further EPA duct cleaning studies have been shelved. However, a scientific study proving the effects of hvac sanitation on indoor mold and fungal populations does exist.
"Effect of heating-ventilation air conditioning sanitation on airborne fungal populations in residential environments," was published in the Annals of Allergy, Vol. 71. Commissioned by an air duct cleaning company in Fort Worth, an independent lab (Mycotech Biological, Inc.) performed this study, which demonstrated a definite decrease in biocontaminants after cleaning.
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