Park yourself in just about any online mold forum, social media group, or chat and you will see a lot of support for the use of ozone to kill mold. Does ozone kill mold? Is it safe to use? Let’s dive into what is a very controversial and loaded topic. I will do my best to keep it simple by breaking this post into digestible parts.
What is Ozone?
Ozone is theprincipalelement of the ozone layer, which traps the sun’s heat and isessential to life on Earth. Unlike breathable, stable oxygen molecules, whichare composed of two oxygen atoms, ozone is composed of three. The third oxygenatom in ozone can easily detach from the ozone molecule and reattach to othersubstances, altering their chemistry.
What Produces Ozone?
In order to useozone to kill mold, you must start with an ozone generator. Ozone generators intentionallyproduce the toxic gas ozone and are sold as air cleaners for commercial andresidential applications. Specifically, they are advertised to deodorize,disinfect, kill or remove dangerous or irritating airborne particles in indoorenvironments including mold.
How Do OzoneGenerators Make Ozone To Kill Mold?
Ozone generatorsproduce the gas in large enough quantitiesthat unstable organic compoundswill react with the gas and, supposedly, be altered so that they will no longerbe irritating or dangerous. Since ozone is composed of threeoxygen molecules, it can combine itself with things like mold and mold spores.It will change them in such ways that it kills the spores and cells thatcompose the mold.
In morescientific terms, ozone generators make ozone by breaking apart oxygenmolecules, a process that can be accomplished in the following ways:
Silent Corona Discharge
All electricaldischarges, such as lightning, produce ozone by splitting normal oxygen andcreating single oxygen atoms, which then attach themselves to O2 toform ozone (O3). Silent corona discharge-ozone generators operate bythis principle.
Ultraviolet Radiation
This process issimilar to the formation of ozone in the upper atmosphere, where the sun’sultraviolet radiation causes O2 to split into individual oxygenatoms. This method is generally regarded as less efficient than coronadischarge.
Does Ozone KillMold?
Yes, technically ozone kills mold. But thereare a LOT of limitations.
Ozone does not penetrate walls, floors, orother surfaces. While it can get into nooks and crannies, ozone can only tackleair born mold and surface mold. Ozone can only go where air can go. As I amsure you are aware, mold is never just in the air.
Ozone will not remove the mold spores it just rendered inactive nor will it kill the mold spores that are growing deep down into building materials and household items. Mold remediation including properly removing the moldy materials and items still needs to be completed.
Using ozone to kill mold does not correct the conditions that allowed the mold to grow in the first place. You have to fix the leak or address the cause of moisture intrusion before you begin dealing with the resulting mold.
In fact, using ozone to kill mold is pointless if you haven’t addressed the root cause and removed all the moldy building materials and household items. As soon as you disturb the mold, spores will go flying and you will recontaminate your home or the contained area.
Ozone typically isn’t used before remediation. There are two exceptions however.
- If you can’t address the mold problemright away, ozone will halt mold growth for a very short period of time.
- Ozone works well as anantimicrobial treatment prior to disturbing mold during remediation. Thishelps to prevent any inadvertently transported spores from being able toreproduce in other areas by deeming them nonviable (dead). This is typicallyonly done when the area being remediated can’t be effectively contained or isin an area of the building where access requires a lot of movement throughother parts of the building.
But wait – before you start thinking thatozone treatments are a good idea… consider this.
The amount of ozone it takes to truly killmold is so toxic it will kill you too. Therefore, you would need to stay out ofyour home for several days if not a week after treatment.
This also means that the vast majority ofozone generators available for sale or to rent to the general public are NOTpowerful enough to produce the amount of ozone needed to effectively kill mold.
In addition, ozone treatments for mold need to be done in an airtight environment. This means that your house would need to be completely sealed up. No gaps around exterior doors or windows, all attic vents sealed, cracks and crevices closed up, etc… Most homeowners and remediation companies won’t go through all this effort. And effort it is.
Does ozone kill mold occurring to the EPA?
This is straight from the EPA’s website.
Available scientific evidence shows that at concentrations that do not exceed public health standards, ozone has little potential to remove indoor air contaminants. Some manufacturers or vendors suggest that ozone will render almost every chemical contaminant harmless by producing a chemical reaction whose only by-products are carbon dioxide, oxygen and water. This is misleading. The EPA does not certify or endorse any air cleaning devices or recommend air cleaning devices or manufacturers.”
HealthConsiderations When Using Ozone To Kill Mold
Unfortunately,the same chemical properties that allow ozone to alter organic material inhousehold air also give it the ability to react with organic material insidethe human body. Ozone’s chemical reactivity does not stop whenit enters the body. It continues to release the extra oxygen atom, whichdamages cells. This released oxygen atom is an oxidizer, the opposite of ananti-oxidant that we might take to improve health.
These well documented scientific and medicalfacts form the basis for a number of health risks related to ozone. Fourdifferent government agencies have restrictions on ozone exposure, includingthe Food and Drug Administration (FDA), the Occupational Safety and HealthAdministration (OSHA), the National Institute of Occupational Safety and Health(NIOSH), and the Environment Protection Agency (EPA).
These agencies agree that low levels of ozone exposure can cause the following conditions:
- Coughing
- Chest pain
- Shortness of breath
- Wheezing
- Throat irritation
- Worsened chronic respiratory diseases suchas asthma
- Increased risk of developingbronchitis or pneumonia
- Compromised ability of the body tofight respiratory infections
There are a lotof other known health risks associated with ozone exposure but the above listare the most concerning.
The EPA notes that it is increasingly difficult to determine the actual concentration of ozone produced by an ozone generator because so many different factors come into play. Concentrations will be higher if more powerful devices are used in smaller spaces. Whether or not the interior doors are closed rather than open will affect concentrations as well. Additional factors which affect concentration levels include how many materials and furnishings are in the room to react with ozone, the level of outdoor air ventilation, and the proximity of a person to the ozone generating device. This means that you don’t really know how much ozone is left lingering in your indoor air.
It is VERY important to note that ozone can dull the olfactory sense, a fact that has led many experts to believe that ozone’s deodorizing abilities are at least partially due to an altered odor perception, rather than any change in the environment. So this means that just because you can’t smell mold doesn’t mean you have really removed mold.
Potential Damage ToItems In A Home From Using Ozone To Kill Mold
Did you know thatusing ozone to kill mold can actually CREATE horrible odors? Yes, ozone istouted as a magic cure for odors but in fact, it can actually create new,nasty, toxic odors.
Basically if youare using ozone for mold then you likely are going to cause materials tooxidize. Here are some examples of materials that are known to give off obnoxioussmells after misuse of an ozone generator. And by misuse I mean running anozone generator too long and/or at too high a setting in too small a space.
- Carpet
- Carpet padding
- Fabrics
- Foam anything
- Most cushions
- Plastics
- Rubber
- Items that have been painted or stained
- Electrical wire coatings
- Fabrics and art containing certain dyes or pigments
In addition tothese materials giving off a horrible (irreversible odor), ozone is known todamage these materials to the point of rendering them useless.
Ozone generators can also damage plants in indoor environments. High levels of ozone will inhibit the ability of plants to open the microscopic pores on their foliage and breathe. Specifically, ozone can cause the following conditions in plants:
- Chlorosis, a condition in which the plant cannot produce sufficient chlorophyll to manufacture carbohydrates
- Necrosis which may lead to the death of the plant as a whole;
- Flecks or small irregular spots
- Small, darkly pigmented areas
- Reddening
Other Risks OfUsing Ozone To Kill Mold
People’ssusceptibility to ozone varies widely. An ozone generator should never beoperated in occupied spaces, and the area should be adequately vented beforepeople or animals are allowed to re-enter.
According to areport produced by the EPA, ozone generators are ineffective at reducing levelsof formaldehydeand carbon monoxide, despite claims by manufacturers.Also, from the toxins with which ozone does react, there is a potential for thecreation of new, potentially more dangerous toxins. For example, ozone mixedwith chemicals from new carpet can create aldehydes, which can irritate thelungs. Other reactions may create formic acid, another irritant. The potentialfor chemical reactions in the average house is difficult to predict.
Ozone treatments will not prevent mold from growing in the first place. A lot, and I mean a lot of people have a false sense of security that if they used ozone to kill mold it will also prevent it.
So Ozone Isn’tThe Safest Or The Best Way To Kill Mold. What Is The Alternative?
The followingalternatives can be usedto deal with an indoor mold situation:
- Professional remediation for larger mold problems
- Removing moldy items and moldy building materials in a properly contained area and cleaning the area with EC3 products or Endurance Bio Barrier Cleaner Prep
- DIY mold removal for shower mold, toilet mold, and other bathroom mold
- DIY washing machine mold removal
- Fogging to remove air born mold
Using HEPA vacuums and HEPA air purifiers are also a good mold prevention plan but are not a substitute for proper mold removal efforts.
If you have outdoor mold, please visit my post about how to remove and prevent outdoor mold for more information on how to tackle that.
Notable references include:
- http://www.ncbi.nlm.nih.gov/pubmed/22095762
- http://www.ncbi.nlm.nih.gov/pubmed/9350226
- http://www.ncbi.nlm.nih.gov/pubmed/7778526
- https://www.cpsc.gov/PageFiles/104545/aircleaners.pdf
- Portions of this article were used with permission from this original article.
Photo Credit – Ozone Graffiti: https://www.flickr.com/photos/duncan/4630974367/
