To Fog or Not To Fog (When Mold is Your Nemesis), That is the Question

by Catherine Fruechtenicht

Cold fogging is something I use frequently as part of my mold maintenance regimen in our home. I am fond of the simplicity of the technique and what it does for my family in terms of minimizing indoor mold exposure to help us stay healthy, but I do realize the controversy when it comes to fogging. In fact, there are many folks in the mold space who are totally anti-fogging. Thus, the burning question remains, to fog, or not to fog (when mold is your health nemesis), that is the question. I obviously have my opinion but want to help you understand why I feel that way; maybe, I can help you sort out if fogging is the best decision for you and your unique and possibly moldy circumstances.

What Kind of Fogging is Best?

Cold fogging is the method I use and suggest. I use fogging for mold maintenance and cleaning purposes, which I will get more into later. Cold fogging involves the use of a machine that employs an inner fan and blower to disperse ultra-fine particles of a fogging liquid into the air and onto surfaces. The idea is that fogging covers everything more evenly and at a greater volume than what you could accomplish by spraying.

I do not use thermal fog in our home. I definitely think hot or thermal fogging has its place, but I do not advise anyone who is not a professionally-trained remediator to use it indoors. You should not be indoors while a thermal fog machine is on and working. It disperses a fogging smoke that can penetrate deep into lung tissue and can displace much of the oxygen in a room. This is not a bad thing for mold and pathogens, though. I find that the thermal fog truly does what it is designed to do and penetrates building materials and porous items to the point that it lingers and dissipates long after the fogging is done. We are chemically sensitive in our home, so this is not a solution for us. Often if there are any other chemical additives in the wood or materials, the thermal fog can cause those VOCs to off-gas noticeably after fogging. I do not know if this is from the heat or something else, but it can create an indoor environment of powerful scents that is not livable for days after the fogging is complete. I have found myself reacting to building materials and furniture, even when I have used non-toxic thermal fogs.

What Exactly is Cold Fogging?

For the purposes of this article, I am going to focus mainly on ultra-low volume (ULV) cold fogging as this is the fogging mechanism I use in our home and feel works best for all of us non-professional mold cleaning warriors out there. ULV fogging equipment is designed to produce very small droplet sizes with a mist that is sheared as it is blown through a rotating nozzle. Sometimes there is even an electrostatic element added to the mist making the droplets adhere to surfaces and particulates floating around in the air better.

Most ULV foggers have a tank to hold the fogging liquid, a pump, and a blower.

According to the VectorFog website, “ULV Fogging works by compressing pesticides or disinfectants through a specially designed nozzle, producing a fine cold mist or aerosol.” Such a fine mist can cover a large area with a blanket of tiny droplets in a short amount of time, using a relatively small amount of solution. The advantage of such a fine mist is that it can fill and reach small spaces and crevices rather easily and can cover but not wet or saturate furnishings or belongings in a room. This is sort of the holy grail when it comes to mold because you want the “dwell time” or time that the fogging solution remains on surfaces to be long enough for it to work efficiently, but you don’t want surfaces to be wetted so much that they are damaged or have to be physically wiped down to dry completely afterward. Mold spores are also often not visible to the naked eye, so you want to be able to treat an entire space without having to physically wipe down or clean every single nook and cranny. Simply put, cold fogging can be a simpler and more economical way to address the overwhelming problem of indoor mold spores on a regular basis.

The size of the droplets produced by the fogger does matter, depending on what you are trying to treat, and can usually be controlled by a dial on the side of the tank. According to current testing and literature on fogging efficacy, the optimal droplet size for tackling pathogens and fungi is between 5-50 microns (μm) in diameter. According to VectorFog, fogging is beneficial against pathogens because, “Foggers produce micro droplets that float in the air for around 10 minutes after application, reaching the most inaccessible parts where conventional cleaning or spraying can’t reach.”

Also worth noting is the fact that only electric or battery-powered foggers should be used indoors. Gasoline-powered foggers produce harmful fumes, are noisy, and are a fire hazard–no sense in treating one problem by creating another one!

What Cold Fogging is NOT Good For

With the technical stuff out of the way, let’s go ahead and get one thing off the table: Fogging is NOT mold remediation. I am going to say that again, “Fogging is NOT mold remediation.”

Whether it be thermal, cold mist, or any other form, you cannot, cannot just spray or “fog” the mold right out of your home. Sorry, friends, it just doesn’t work that way. Believe me, I have tried. I wish mold remediation were that simple and straightforward, but it is not.

Mold remediation must consist of source identification, stopping and/or fixing the REASON for the mold growth—a leaking pipe, overflowing gutters, a moist crawlspace, high humidity, etc.—removing the source of the mold, aka physically removing the contaminated building materials or physically removing the mold, and then cleaning all surrounding areas and belongings impacted by the mold. Fogging can, and, in my opinion, should be part of the cleaning step of remediation, but should NOT be the main method employed to solve the mold issue.

What Cold Fogging Can and Should be Used For

When it comes to mold, fogging has some unique benefits:

The first good use for fogging, and also arguably the most controversial, is using it as a helpful cleaning tool for someone who is mold sensitive and who cannot fully control his or her environment. If you read my blog Mold Free Living, you may be familiar with me calling fogging the great mold Band-Aid. The reason I use this term is that, if a person is renting, traveling to a temporary home, or just cannot afford to do all of the remediation required at the time, fogging can be a helpful and temporary Band-Aid to keep mold counts down. Remember, the operative word here is “temporary.” If the source or the reason for the mold is not fixed or removed (as I stated previously), the mold will return and will continue to grow no matter how much fogging is done. In other words, like a Band-Aid, fogging can stop the bleeding. It cannot stop the need for stitches, or major surgery, though. Fogging, when done correctly, which I will get to later, can make things more livable until a better solution, like moving to a mold-free environment, or full-scale, professional mold remediation can occur.

Fogging as a Band-Aid approach is also notable for any mold sufferers out there for its ability to save a relationship. Wait! Please hear me out–I was the one in my marriage shouting, “It’s mold!” for a long time before my spouse was ready to accept that mold was causing our health issues. When one person in the home is sick, and the other feels the home is fine, sometimes fogging can bring noticeable relief to the sufferer, so the pivotal “Aha moment” can occur for the mold skeptic. Sometimes fogging can even provide an overactive immune system the respite required to kickstart the healing process when the other partner is opposed to leaving or buying into remediation just yet. This is NOT me saying fogging is a cure-all. This is just me saying, it’s easier to convince someone to fog than to move. If nothing else, at least fogging can sometimes get that healing ball rolling in a more positive direction.

The second, but MOST important use and benefits of fogging are as a mold maintenance and cleaning tool. Let’s face it, once you are mold sensitized, it is an immune response that is sort of hard to shake. Your cells can become programmed to recognize the danger mold poses, so even a very small exposure, especially at the beginning of your healing, can bring major setbacks. Thus, anything you can do to continually address mold in your home is a good thing. For me, fogging was not only a cleaning tool but also environmental therapy of sorts; it helped me to feel more in control of what was a very scary and out-of-control living situation.

The Fogger and Fogging Solution I Use

The fogger I am using now and have returned to after trying a few other models is the EC3 Sanitizer Fogger. You can find it in the Micro Balance Health Products store. Other foggers I have used and liked are the Vectorfog C100 ULV Electric Fogger and the Fogmaster Tri-Jet 6208. All three of these foggers are relatively lightweight—the Fogmaster is the heaviest, all require only a regular power outlet to do their thing, and can easily be carried around and held with one hand, even when filled with one gallon of fogging solution. I like the EC3 Sanitizer Fogger best because it is easy to control the droplet size with the small dial on the side of the tank—I like a finer mist for larger rooms with high ceilings and a medium mist when I am more concentrated on fogging a certain object, like a couch, and because I can set it on the floor or on a table in a room and swivel the head with one hand. This allows me to direct the fog up to the ceiling or at the corner of the opposite side of the room with ease. It provides a droplet size of 10–50 microns, with a droplet throw of 15 feet, and coverage of 60-80 square feet. This is more than enough for the rooms in our home. (Note: The website Mold Help For You has a great article on foggers if you want to take a deeper dive into different kinds and brands.)

For fogging solution, I use the EC3 Mold Solution Concentrate. I highly, highly recommend you carefully consider what you are going to fog your home with as much or MORE than you consider whether or not to purchase a fogger. I choose to use the EC3 because it is non-toxic, botanically-based, and has a Safety Data Sheet with all zeros. It can be used without having to wear PPE and we do not have to vacate our home or worry about breathing in the fog while cleaning. It is also safe for almost all surfaces and materials.

As important as its safety is the fact that EC3 has been proven effective at eliminating many of the most dangerous mycotoxins common in water-damaged buildings. I also happen to love the way that it smells or doesn’t smell. If anything, it provides a bright, citrusy essence and deodorizes everything. It is sort of like no smell, just fresher.

Other beneficial fogging solutions are Decon 30, peroxide, and hypochlorous acid. Of those three solutions, I believe Decon 30 is the only other one that can be used in a cold fogger without using PPE. Peroxide and hypochlorous acid should not be inhaled in very small particle sizes. This is not to say that peroxide and hypochlorous acid are not effective. Both are wonderful cleaning agents and wonderful mold adversaries. You just have to be more careful when using them and take the proper precautions. I would also wipe things down after using peroxide because it can mark or remove the color from some surfaces and materials.

How I Use My Fogger

Once a month, I routinely use my fogger as part of maintaining and deep cleaning our home. First, I dust and HEPA vacuum the whole house thoroughly. I truly try to clean every hard surface the best I can. If you do not have time to do your whole home all at once, you can do room by room. You really want to remove as much surface dust and debris as you can. Then, I fill the fogger tank with one gallon of mixed EC3 solution. It comes as a concentrate, so you have to mix it per bottle directions with distilled water before use. One gallon of mixed solution easily fogs about 2,600 square feet. It more than enough to cover the interior of our home with some leftover in the tank.

I start fogging in one room on the bottom floor. I plug the fogger in, adjust the dial, turn it on, and, holding the fogger, I direct the mist from ceiling to floor from one side of the room to the other. I am careful to keep moving and to methodically cover the whole space and contents with the fog. If you have items you are worried about ruining, you can cover them before fogging, but if done correctly, the fog should dry quickly and should not cause any issues. When I am done with one room, I move to the next. When I am completely finished fogging, I switch on all of our overhead fans to encourage drying and air circulation. I then like to go back and HEPA vacuum floors. Sometimes I rewipe some flat surfaces as well. If it is a particularly moldy month outdoors, or a month with high humidity, I may do this more often. I also like to fog any new items of furniture we choose to bring into our home. If we have been traveling, I will fog our suitcases and wipes them down before bringing them back into our home too.

I would not suggest fogging any attic space or unfinished spaces where there is exposed fiberglass or poor ventilation. Those spaces are better and more safely addressed in other ways, in my opinion. Finally, you don’t have to turn your HVAC off while fogging, but if you choose to leave it on, I would recommend using that as an opportunity to change your air handler/furnace filter. Many filters lose their electrostatic charge if they encounter moisture. This will make the filter lose its ability to collect dust and particulates as efficiently. You don’t want that when trying to maintain a mold-free home!

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