Will Fogging Kill Mold?

Like the answer to most questions, it isn't a black and white "yes" or "no."  There are many variations of fogging disinfectants that range from being ineffective to extremely effective in their ability to kill black mold and other types of mold.

You can learn more about the range of options below or, if you want to cut to the chase and learn about the research, studies and customer validation that back up the best mold remediation method on the market? click here.

Will Fogging Kill Mold?

If we had to absolutely give you a "yes" or "no" answer, we would err on the side of saying "no."

Wait a second. How can a mold remediation company who uses a dry fog to treat mold say "no"?

Because in most cases it's the truth.

It's like asking whether a creme or lotion can relieve itching from eczema. You are going to have a whole range of options with varying results. With most, frankly, not helping much at all, and at best. very temporarily.

Keep in mind that we are talking about killing mold.  To eliminate or remove or hide the unappealing visual aspect of mold, every type of fogging has zero effect.

Why Consider Fog?

People pay for a professional service provider for two reasons... they don't have the time to do it themselves and, more importantly, they believe a professional will do a much better job than they could.

But what if you had the time?

Couldn't you just buy a fungicidal spray or wipes and clean off a moldy surface yourself? Then if necessary, cut out and remove unsightly mold yourself as well?

You could, but 95% of mold growth in homes is invisible. Hiding behind walls and other surfaces.

Professionals use tools like infrared cameras, or moisture meters to find and insure all hidden sources of moisture have been identified and addressed. Because wherever there is greater than 60% humidity or moisture for more than 24 to 48 hours, there will be new mold growth.

Mold spores are everywhere. Whether you live in hot dry desert or a humid place like Florida, mold is there, floating through the air in search of moisture and the right conditions to grow.

So, given the fact the mold is omnipresent and often complex to treat because it is hidden; professional equipment and experience then becomes necessary to effectively and efficiently treat it.

Ok, that's why you need a professional, but why fogging?

Other than choosing an effective disinfectant, the most important aspects for effectively killing mold with that disinfectant are...

  • coverage
  • dwell time
  • droplet size


Practically speaking, a fog that fills the entire volume of your home and contacts all surfaces including all furnishings, the interior of your HVAC system, the walls, flooring and ceilings, and pushes its way into every nook and cranny is going to do a far better job and do it in far less time than taking out wipes or a spray bottle.

For this reason, from a sheer coverage standpoint, Fog should do a better job than any other mold remediation methodology.

The alternatives of UV light, professional scrubbing or sprays are impractical for reaching all surface areas.  Physical removal through demolotion on its own is also sub-par. Without killing mold, demolotion releases high concentrations of live mold into your air, so it can then easily spread throughout your home or workplace.

As for dwell time (also known as "contact time)... the disinfectant used simply needs to remain in contact with the mold long enough to kill it. This is a very simple concept that you can ask a mold company about, and if they don't know the answer to what their required contact time is, then there is no way for them to know if thy are applying their fungicidal disinfectant long enough to be effective.

The last consideration is droplet size.

Fog Types and Droplet Sizes

If a disinfectant can't be reduced to a small enough droplet so it can contact and reach mold embedded deeply in a substrate, the worst fungicidal disinfectant is just as good as the best fungicidal disinfectant in the world, for that mold.

ULV Fogging

The ULV, or ultra-low volume fogging process is a technique that aerosolizes a disinfectant, like all fogging. The backpack and handheld nozzle You know its ULV when you see the Ghostbusters style backpack and handheld nozzle in the service provider's photos.

The fog is turne off and on with a trigger that activates the built-in motor which forces the air in the nozzle to swirl in a way to create a low-pressure mist. The droplet size ranges from 5 to 30 microns.  Still very small, but not small enough.

  • According to the EPA, Mold spores typically range from 2 to 100 microns in size (microns = micrometers). At times even smaller than 2 microns. Black mold, also known as Aspergillus niger and perhaps the most common mold concern is roughly 3 to 5 microns.  The droplets from ULV will get much of the mold, but will clearly miss any black mold embedded in small micron gaps.
  • The larger, wetter ULV droplets condense quickly. As a result the dwell time contact with the majority of airborne spores and harmful mycotoxins is never met and they are thereby not destroyed.

If airborne spores are not systematically eradicated, simply because they never came into contact with the disinfectant or came into contact long enough, then it will eventually settle on a surface, and when conditions are met, begin to grow again.

It is true that it is impossible to get rid of mold. Like humidity it is always with us. Mold's ability to make a person uncomfortable depends on its concentration.  That's how humidity works too!

ULV Fogging wouldn't exist unless it got results. But on average it is going to leave a higher concentration of airborne mold than other fogging techniques.


One effective Sterilant is Ozone fog, a gas made up three oxygen atoms - 03. Normally Oxygen is made of just two atoms - 02. The extra Oxygen atom in ozoneis prone to detach from the other two oxygen atoms and reattach to other molecules, thereby oxidizing them in the process. This process brakes down membranes and other key components of any microorganism, destroying all of these microbes in its path. What's more, ozone gas is picometers in size, or roughly a million times smaller than the smallest mold spore.

This sounds good, except 03 concentrations necessary to effectively kill mold would have to be so high that it would render a space to toxic to occupy. As the same chemical properties that allow high concentrations of ozone to react with the organic material in microorganisms, can react with similar organic material that makes up the body.  The EPA has stated:

"Available scientific evidence shows that at concentrations that do not exceed public health standards, ozone has little potential to remove indoor air contaminants... ozone is not effective at removing many odor-causing chemicals... ozone applied to indoor air does not effectively remove viruses, bacteria, mold, or other biological pollutants."

The question is then whether sufficiently high concentrations of ozone in spaces that are occupied for days may be effective? In response to that question, the EPA has also stated:

"...little is known about the chemical by-products left behind by these processes (Dunston and Spivak, 1997)" and "Ozone can adversely affect indoor plants, and damage materials such as rubber, electrical wire coatings and fabrics and art work containing susceptible dyes and pigments (U.S. EPA, 1996a).

Ozone could still be the best option, however it is important that if you decide to go that route that you ensure it is at the right concentration levels, and that you are out of the location being fogged for enough time to permit safe re-entry.

Dry Fogging

Low concentration ozone is considered useless, and ULV fogging can't achieve the necessary dwell time in the air to eliminate airborne mold, While high-concentration ozone can be unsafe and damaging.

This leaves us with the last general category: dry fogging.

Any legitimate dry-fog is composed of droplets that are 10 microns or smaller.  Our average droplet size coming out of our fogger is 7.5 microns which then separates into increasingly smaller particles after release; resulting in droplet sizes as small as half a micron (.5 micrometers).

Our dry fog equipment is patented because of its novel way of atomizing liquids into a fog so that the average droplet size is much smaller than a ULV can produce, and it doesn't condense on surfaces and instead dwell in the air for far longer than the required dwell time necessary to kill every type of mold spore and their associated, and even smaller mycotoxins.

This is crucial... it means when we dry fog an HVAC system, for example, that the inside top of the HVAC ductwork will receive equal disinfection treatment as the bottom.

Something else we didn't discuss was is the benefit of back-pressure.  Our foggers apply pressure to our dry fog, forcing our hospital-grade sterilant to dwell on every surface and object in your location.  No other method comes close to the coverage achieved. We estimate that, depending on the home and it's surfaces, that we sterilize up to 10X to 1000X the surface area.



Killing mold using fungicidal disinfectant is an essential component to mold remediation.

Regardless of the type of fogging used, it's usually not enough on its own.

Of course the source of moisture must be resolved to ensure mold doesn't return. But there is also the visible component that needs to be rectified, which typically means some demolition and reconstruction.

However for efficacy as it relates to health and ensuring safety, we believe the science shows that the dry fog is the clear winner.

It has the micron size to reach mold and its roots by penetrating deep into the substrates mold is growing on. It also is dry enough to remain suspended in the air, with added benefit of positive air pressure to push into every space within your location where there is air flow, allowing it to access hidden spaces behind walls, inside carpets and soft furnishings.

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