Indoor Air Quality issues are fast becoming part of the general public’s conscientiousness through the mass media’s portrayal of proliferating toxic mold that threatens our very lives.  Non-qualified commercial and residential duct cleaning services can be just as hazardous.  The question must be asked…does air duct cleaning really help? 

The first step to consider before having the ducts cleaned is to determine if the ducts are the source of health problems.  Keep in mind, the source of the problem may be elsewhere and cleaning the ducts may not be the answer.  Contact a reputable environmental consultant who can perform a walkthrough that includes a series of inexpensive tests to determine the environmental status of your home or office.  Simple tests utilizing Bio-Scan^TM can assist in determining the microbial load within an air handler and air conveyance system. 

What Does Duct Cleaning Entail?

Duct cleaning entails cleaning the various heating and cooling system components of forced air systems. These components include the supply and return air ducts and registers, grilles and diffusers, heat exchangers heating and cooling coils, condensate drain pans (drip pans), fan motor and fan housing, variable area volume (VAV) boxes, fresh air ductwork, and the air handling unit housing. If the decision is made to have the system environmentally cleaned, it is important the service provider environmentally cleans all the components so unclean parts will not re-contaminate the system again.

The service provider should take preventive steps to protect individuals from exposure to dislodged contaminants during the cleaning process. These steps may include the use of containment barriers; the utilization of negative air machines (NAM) employing High Efficiency Particulate Arresting (HEPA) filtration rated 99.97% efficiency for particulate size of .03 microns on the cleaning equipment, effective “tools of the trade” to facilitate proper removal, and the use of employees who are trained in OSHA safety practices.  In an office type building, remediation should be performed at night, to again minimize the occupational exposure of the tenants to potential contaminants disturbed during the remediation processes.

Signs Ducts Should Be Cleaned

There are several factors that help determine if the duct system should be cleaned. One major factor is visible mold growth inside hard surface ducts or on other components of your system. Be aware that although a substance may look like mold, it may not be. Only a laboratory analysis can accurately determine whether a sample is mold or simply debris that resembles it. If the air duct insulation is saturated with water, it should be removed and replaced and the cause of the growth corrected before the cleaning or removal occurs.

Other factors include rodent or insect infestation and a clogged system that actually releases contaminants into the building or home through the registers.

Risk Factors

If proper duct cleaning procedures are not followed, duct cleaning can cause more dust, debris, and molds to be released into the air.  An inadequate negative air machine collection system can cause this problem. Also, there is the possibility the service provider can damage your ducts or heating and cooling system, which could result in increased heating and air conditioning operational costs, expensive repairs or replacements.

Listed below are questions that should be posed to the prospective duct-cleaning contractor:
·         How long has the service provider been in business?
·         Do their respective state’s Department of Business and Professional Regulation (DBPR) require licensure?
·         What are the qualifications of the firm?
·         Do they guarantee their work?
·         What is the guarantee?
·         Does the firm work with the medical community? (Health implications of work)
·         Are their chemicals registered with the EPA for specific ductwork applications? (Fiberglass vs. Sheet Metal)
·         What would they do if mold, fiberglass, dust, pollen, and dander increase after the cleaning process?
·         Are the technicians who will be performing the work environmentally trained?
·         What are their backgrounds? Their experience? Have they been trained in the following:
          -  Respiratory Protection Program:        1910.134
          -  Hazard Communication Program:       1910.120
          -  Confined Space Program:                  1910.146
          -  Lock Out - Tag Out Program:             1910.147

An EPA Study

The information provided below are excerpts from EPA Pilot Field Study EPA-600/R-97-137 December 1997 prepared by National Risk Management Laboratory:

The EPA conducted a nine-home study in 1997 to investigate the impact of mechanical air duct cleaning (ADC) methods on indoor air quality (IAQ) and system performance.  Only mechanical ADC methods were evaluated.  Surface treatments, such as biocides or encapsulants, were not part of the study.  Pre- and post-ADC measurements were used to evaluate impacts.  These included deposited duct dust measurements, airborne particle and fiber concentrations, microbial bioaerosol and surface sampling, and system performance factors such as temperature, relative humidity, airflow rates, and static pressure. 

Surface sampling in ducts indicated that mechanical ADC is effective in removing adhered dust and dirt (see fig. 1).  Mechanical ADC did not significantly reduce bioaerosol or microbial density in the houses studied.  None of the test houses were considered to be biocontaminated; therefore, a small change would not be surprising.  Fungal levels were generally higher than bacterial levels, and ADC had the most impact on the ducts with the highest levels of fungi and noticeably reduced the level of fungi in surface samples collected from ducts in most houses.  Mechanical ADC methods alone did not substantially reduce bioaerosol and culturable surface microbial levels.  Surface treatments such as biocides or encapsulants may be required if it is determined that substantial reductions are necessary.

Contact a professional if you think duct cleaning might be a good idea for your facility or residence, but keep in mind, the EPA does not establish duct cleaning standards, but there are other industry standards.
Unless you fully understand the pros and the cons of chemical biocides or sealants do not allow the use of them.

One Final Thought

Remember, when your air handling system and associated air conveyance system was newly installed, it did not contain the debris, mold, moisture, construction materials etc. that it may presently contain 5, 10, 15 years later.  If your air handling unit and/or air conveyance system is dirty or contaminated, professionals should be contracted to environmentally clean it.  Typically, 1-10 lbs. of debris will be removed from an older AHU/ACS system.  Duct cleaning can help only if it’s done right.

As with any professional, check references thoroughly to be sure other customers were satisfied and did not experience any problems with their heating and cooling system after cleaning.
 
For more information contact
Kevin McKee, Director of Remediation Sciences 
800.422.7873 ext. 803 or
email kmckee@pureaircontrols.com