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ArticleTechnical Article

Setting the Record Straight - Is Sporicidin Safe for Duct Cleaning?

By HHI Staff

Question: I had my ducts cleaned and treated. Is that possibly the source of my burning eyes? Is Sporicidin safe for duct cleaning?


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A: Reactions after duct cleaning can be caused by mold spores, allergens or dust being stirred up, as well as exposure to cleaning or disinfecting chemicals. Without knowing more details such as what cleaning process was employed or what chemicals were used, it would be unproductive to speculate.  


Sporicidin Disinfecting Solution (US EPA registration number 8383-3) is an EPA registered disinfectant commonly used by NADCA (National Air Duct Cleaners Association) certified duct cleaning professionals to clean and deodorize household and commercial HVAC ducts. Professionals often select Sporicidin Disinfecting Solution for one or more of three reasons:


1.       The active ingredients in this product, phenol and sodium phenate (a buffered phenol), have a track record for safety. Interestingly, these active ingredients have been used in a throat spray product named Chloraseptic® for more than 5 decades (Chloraseptic® is a trademark of Prestige Brands Inc.)

Should chemical biocides be applied to the inside of air ducts?

by EPA


No products are currently registered by EPA as biocides for use on fiberglass duct board or fiberglass lined ducts so it is important to determine if sections of your system contain these materials before permitting the application of any biocide.

Air duct cleaning service providers may tell you they need to apply a chemical biocide to the inside of your ducts to kill bacteria (germs), and fungi (mold) and prevent future biological growth. Some duct cleaning service providers may propose to introduce ozone to kill biological contaminants. Ozone is a highly reactive gas that is regulated in the outside air as a lung irritant. However, there remains considerable controversy over the necessity and wisdom of introducing chemical biocides or ozone into the duct work.

Among the possible problems with biocide and ozone application in air ducts:

  • Little research has been conducted to demonstrate the effectiveness of most biocides and ozone when used inside ducts. Simply spraying or otherwise introducing these materials into the operating duct system may cause some of the material to be transported through the system and released into other areas of your home.
  • Some people may react negatively to the biocide or ozone, causing adverse health reactions.

Chemical biocides are regulated by EPA under Federal pesticide law. A product must be registered by EPA for a specific use before it can be legally used for that purpose. The specific use(s) must appear on the pesticide (e.g., biocide) label, along with other important information. It is a violation of federal law to use a pesticide product in any manner inconsistent with the label directions.

A small number of products are currently registered by EPA specifically for use on the inside of bare sheet metal air ducts.

In the meantime...


Before allowing a service provider to use a chemical biocide in your duct work, the service provider should:

  • Demonstrate visible evidence of microbial growth in your duct work. Some service providers may attempt to convince you that your air ducts are contaminated by demonstrating that the microorganisms found in your home grow on a settling plate (i.e., petri dish). This is inappropriate. Some microorganisms are always present in the air, and some growth on a settling plate is normal.
  • Explain why biological growth cannot be removed by physical means, such as brushing, and why further growth cannot be prevented by controlling moisture. If you decide to permit the use of a biocide, the service provider should:
  1. Show you the biocide label, which will describe its range of approved uses.
  2. Apply the biocide only after or in conjunction with proper cleaning.
  3. Always use the product strictly according to its label instructions.

While some low toxicity products may be legally applied while occupants of the home are present, you may wish to consider leaving the premises while the biocide is being applied as an added precaution.


2.       The EPA categorizes disinfectants according to what precautions must be taken when these chemicals are used. Sporicidin has been categorized a Level IV (the safest category) disinfectant for every human exposure test except for eye exposure, where it has been ranked a Level III. Because of the relative safety of this product, you’ll find the precautionary statement “Keep out of reach of children” on the Sporicidin label. Other disinfectants will list precautionary statements indicative of their more hazardous properties, such as “Danger” (Category I) or “Warning” (Category II).

3.       Sporicidin Disinfecting Solution is more environmentally friendly than some other disinfectants. Under conditions found in most homes and offices, active ingredient residues evaporate at a rate of roughly 50% in a 24 hour period. This means that after 1 week, less than 0.1 grams of active ingredient would be left in a 2000 square foot home if the duct cleaners applied 4 ounces of Sporicidin Disinfectant Solution. If accidentally spilled on the ground, Sporicidin Disinfectant Solution generally breaks down in less than a week. Sunlight readily breaks down phenol and some studies have shown that Sporicidin Disinfectant Solution does not harm fish or other small animals.

When properly used, Sporicidin is apparently effective for deodorizing and cleaning ductwork and, according to the manufacturer, is used in tens of thousands of applications each year in North America.  

Recognizing that in any given crowd a handful of people are sensitive to chemicals, duct cleaners and other restoration professionals who apply chemicals in homes and commercial buildings have been trained to leave a rag or paper towel that has been saturated with the cleaner or disinfectant in a lavatory sink or in a bucket in a room or enclosed space that has an exhaust fan or window directly to the outdoors. This “previewing” of the building occupants by giving them an opportunity to be exposed to the disinfectant in a controlled environment before the widespread application of the product can help to avoid a home owner or office worker having an adverse allergic reaction later.  


Reference: Stephen Leung, Director of Development, Contec, Inc., Sporicidin Division


(Note: The information presented in this article is current and accurate to the best of our knowledge. As more information becomes available, we will provide updates.)



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Setting the Record Straight - Is Sporicidin Safe for Duct Cleaning?:  Created on November 16th, 2009.  Last Modified on December 23rd, 2009


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