Friday, July 22, 2016


Is Ultra-Violet (UV) Light the Right Solution for Mold Remediation?

By Edward R Close, PhD and Jacquelyn A Close
© EJC Advantage, July 22, 2016

Ultra-Violet Light (UV) is best known for its ability to eliminate bacteria. And the effectiveness of germicidal UV has not only been recognized but also incorporated in the Facilities Standards for Public Buildings as follows:

"Ultraviolet light (C band, UVC) emitters/lamps shall be incorporated downstream of all cooling coils and above all drain pans to control airborne and surface microbial growth and transfer. Applied fixtures/lamps must be specifically manufactured for this purpose."

You need to know, however, that while UV emitters placed in the airflow downstream of AC coils and drip pans may help improve the air quality coming from HVAC systems, they will have no effect on mold colonies growing elsewhere in a building.  In addition, the effectiveness of UV in HVAC systems depends on a number of factors such as: rate of air flow, humidity, placement and distance between the UV light and the microorganisms it targets, irradiation time, as well as other variables occurring in real world environments that make calculation of effective UV dosage very difficult.

It is true that UV light will destroy the DNA of harmful microorganism given a high enough dosage over a sufficient length of time. And germicidal UV systems may be successfully utilized in hospitals and public buildings to inhibit microbial growth in HVAC systems, thereby improving the quality of indoor air and decreasing the risk of bacterial and fungal infections in people with compromised immune systems and/or open wounds. But the question is this:  Is it an effective solution for remediating a building infested with mold? In a word: NO.

The problem with UV or UVC systems for addressing mold infestations is the fact that they only treat the airstream within the HVAC system, and cannot safely address the many sources of mold spores that may exist in a building in places other than inside the air-handling system.

Sources of mold around leaks, in moisture from humidity condensation, and other conditions that lead to the growth of mold super-colonies, are not affected by the air flowing through an HVAC system. Sources of mold spores can be also be found on surfaces, such as the exterior of HVAC ductwork, walls, floors, in bathrooms, in fact almost any surface inside or under a building. While some spores in the air flowing through a UV system may be killed, UV only treats the air that flows through the system and nothing more.  

For UV light to destroy mold spores, one must have two things —
  1.  Sufficient UV light intensity, which decreases rapidly with distance from the bulb, and
  2.  Sufficient “dwell time” which is the time that the mold spore is actually exposed to the UV light.

The amount of exposure time required to destroy a mold spore varies greatly for the different species of mold. Some spores are destroyed after a few seconds — others require 8,000 seconds or more. That’s more than 2 hours.

The air traveling in an air duct is moving at a minimum of 100 feet per minute. You have to ask: what are the chances that a mold spore in the airstream inside the ductwork will be exposed to the UV light for a sufficient length of time? Pretty slim.

And while the air may be re-circulated, mold spores can fall out anywhere along the path from the outflow vent to the intake vent, and never be returned to the UV system for additional treatment.

“UV lights have been shown to reduce mold when exposed continuously to the coils of the HVAC system. Cleaning the coils periodically would accomplish the same result.”

Cleaning with essential oils and essential-oil-based cleaners will be far less costly. 

So, UV and UVC systems may be helpful in improving indoor air quality, however, they are not effective in eliminating most mold infestations and may pose health dangers if not properly installed, shielded and maintained. In general, they are far more costly and less effective than using essential oils and essential oil-based cleaners.

Limitations of UV or UVC Systems

  1. They cannot address many sources of or surfaces infested with mold
  2.   Intensity and “dwell time” requirements do not address all mold species
  3.   Humans have DNA, and since UV and UVC are known to destroy the DNA of microorganisms, special handling of lamps, installation of shielding, and added protection for human inhabitants increase the risk of damaging the DNA of humans that come in contact with the light, as well as increasing the costs associated with its installation and maintenance.

Is UV right for your mold problem?
The best answer is that it depends on the building and the budget. It is only one of a number of options that can be utilized for improving air quality as part of the solution for a building with a mold problem. It is not a solution in and of itself, and not necessarily even a part of the best possible solution for a given mold problem. There are far more cost-effective options available that can help you address all sources, surfaces, and air streams. 

We have more than 20 years of mold remediation experience, over 10 years experience using The Close Protocol to Remediate Mold in Buildings, and many hundreds of personally-supervised mold remediation projects where The Close Protocol was employed, and we have found that essential oils and essential-oil based cleaners have proven far more cost effective as well as more effective and complete in addressing and remediating mold in buildings.

Many discussions of mold remediation options and detailed answers to questions about using the Close Protocol for Mold Remediation in Buildings are freely provided on this website. For those of you who require additional help, please contact us.

Basic information about the ten-step protocol is presented in Chapter 7 of our book, Nature’s Mold Rx, The Non-Toxic Solution to Toxic Mold. The book also discusses twenty (20) case studies in detail, and most of the questions that may arise when the protocol is applied are answered in the book.

Be blessed richly and may you always enjoy Vibrant Health!
Very Sincerely,

Dr. Ed And Jacqui Close
EJC Advantage LLC

P.S.:  If you have gotten value from the information shared, please take just a couple of minutes to comment on our posts in the Comments Section below and share your experiences. We love to hear from you this way. We also invite you to share this on Social Media. Thank You!

NOTE:  The information above is copyright protected and all rights are reserved.
Copyright EJC Advantage LLC and Edward R Close and Jacquelyn A Close, 2016 and continuing.  This information and parts thereof may not be reproduced, copied, pasted, or posted elsewhere through any means whatsoever without written permission from the authors. We invite you to provide a link to this webpage if you wish to share this information with others.


  1. Now you don't have to worry about mold in your air ducts. You will get many tips from how to get rid of mold in air ducts in Marietta for solving this problem. Because here problems and solution both are nicely written so you don't need to tensed about it.

  2. This whole is about light the right solution for recomendation. I have been all these things which were showing you an interest in all the material which is just describe on website and all that which you want for you, This is must and hope you like it ever when you see this.

  3. Thankyou for this wondrous post, I am glad I observed this website on yahoo. Smoke Removal

  4. Form development can be a difficult issue. This is on the grounds that it can prompt property harm other than expanding the danger of medical problems to everybody who dwells there. This makes shape remediation significant when the issue is recognized.mold remediation in cherry hill nj

  5. Yes i am totally agreed with this article and i just want say that this article is very nice and very informative article.I will make sure to be reading your blog more. You made a good point but I can't help but wonder, what about the other side? !!!!!!Thanks mold removal contractor

  6. There are five levels of mold remediation. This you should use to guide you on when to get a professional mold remediation company or just take care of the issue yourself. Mold Remediation