By: Licensed Mold Assessor Brad Fishbein
January 14, 2023
Mold fogging is a process of applying a solution made of fungicide and distilled water in the air to kill aerosolized mold spores and knock them down to the ground. The solution is atomized into small droplet size and creates a mist that is sprayed into the air using a device with low solution volume but high pressure.
Some people also refer to fogging as a mold bomb.
While fogging is certainly a useful part of the mold remediation process or even a stand-alone treatment of mold, there some caution that must be taken when using this method.
There are conflicting opinions out there. One argument is that it's a temporary solution while others will claim it's all that is needed for environmental cleanup in an indoor living environment.
There's a bunch of stuff you need to know before you either fog your home yourself or have a mold remediation professional do it to get rid of a mold problem.
In this article we are going to discuss:
Mold grows by landing on a wet surface and colonizing.
Mold spores can then branch off and become airborne making them difficult to remove. Mold can affect mold sensitive people when it's airborne. With the fogging process, after landing on the spores, the solution suppresses the mold, killing it.
And this is how it does it:
The solution disrupts the mold's cell membrane and stops them in their tracks from reproducing.
Fogging an entire area can also prevent mold spores in a home from coming into contact with the water-damaged area and prevent future growth on surface areas.
There is a little bit of an issue with this though, but more on that later.
While fogging will destroy microorganisms, it doesn't mean the appearance of mold growth or actual mold spores will be completely gone. Mold fogging kills molds and causes them to fall on the ground but the dead mold fragments are still present within the home.
Allowing dead molds to remain in your home could lead to health-related issues. Using a HEPA vacuum is advisable to clean up the molds.
Fogging can be done in two ways, wet fogging and dry fogging.
Wet-fog mold removal uses a mold fogger to dispense the cleaning solution into the air in a fine mist. This method is safe for properties that are not moisture-sensitive.
The mist on top of knocking mold spores from the air can land in tough-to-reach areas where mold tends to grow.
On the other hand, dry-fog mold removal dispenses the cleaning solution into the air as vapor. This vapor can also knock mold spores down from the air and also allows tiny particles to land on the affected surfaces, killing mold.
Unlike wet fogging or a mold bomb, dry fogging doesn’t wet surfaces in a home.
The cleaning solution in the form of steam or vapor circulates the room, falling on the mold spores.
Both processes allow the solution or vapor to penetrate cracks and crevices where mold might be hidden.
Fogging can be safe if the chemical solution is non-hazardous and biodegradable. But that is not always the case to the product should be checked to ensure it is approved by the Environmental Protection Agency (EPA) for fogging. No antimicrobial pesticide should ever be used. Any solution used should have non-toxic chemicals present in the solution.
Whether or not the solution is something biodegradable or a fungicide, proper PPE needs to be used when fogging to try and resolve a mold issue in a home.
Proper PPE includes gloves, an overall, an N95 or half-mask respirator, and goggles.
If the solution contains hydrogen peroxide, it can be harmful when inhaled or damage your household items. A solution that works and dries quickly can be a good option in homes with children and pets. But fogging SHOULD NEVER be done with occupants in the home.
Water-based botanical products may not be ideal for fogging. Such products may fail to penetrate through the hydrophobic mold spores. Besides failing to eliminate molds, these products can lead to moisture problems in your home.
While fogging kills mold and eliminates the musty odor, it’s not the most effective way to eliminate molds in your home. Fogging does not resolve the root cause of mold infestation. Mold has a roots-like system called hyphae which grow into the drywall, insulation, and ceiling blocks. If you use fogging for mold removal, you’ll only kill the visible mold spores.
And killing mold should never replace removing mold.
Eventually, you’ll start seeing mold recurring because fogging won’t eliminate the actively growing hyphae.
If mold is present inside the walls or behind baseboards, they will still be there after the fogging is completed.
More recently, more and more mold remediation companies have been promoting dry fogging services and trying to pass it as proper remediation.
These companies claim it's a safe and effective mold remediation service for the entire space. They also claim it's much more cost-effective which is true because nothing is being removed.
The Engineer Research and Development Center even did a study for the US Army indicating dry fogging can be effective in improving airborne mold counts and be cost-effective.
Here's where the problem arises:
Dead mold in the home can still cause allergic or toxigenic responses. Fogging can improve air quality in the home when it's done but if dead mold is present in the home, the spores can still become airborne at a later time, especially if disturbed. It can just be a band aid.
The bottom line is the mold fogging can certainly kill mold, it should not be used as stand-alone mold remediation.
After addressing the root cause of mold growth, you can use fogging to eliminate the remaining molds. This process involves using the cleaning solution on the surfaces to get rid of contamination that resulted from the sources of mold.
The cleaning solution takes around 30 minutes before it kills mold spores depending on the size of the area.
Mold fogging as a DIY project is not recommended. There are a few reasons for that:
The best fogger should produce fine particles. A dry fogger should generate particles less than 15 microns. On the other hand, a wet fogger should produce particles less than 50 microns.
Here are the types of foggers that can be used:
Handheld fogger: It is lightweight and a good choice to carry to different locations around a home.
Stationary or static fogger: This fogger is ideal for eliminating molds in larger areas. It’s a heavy-duty fogger that dispenses mist or vapor to treat up to 400 square feet in one go. This fogger can eliminate molds in hard-to-reach parts such as crawl spaces or attics.
Single-use fogger: This fogger is specially designed to use once only.
Multipurpose fogger: Besides mold treatment, this fogger is ideal for fumigating insects, sterilization, and sanitization.
How to use a fogger can determine if it will effectively eliminate mold in a building. The manufacturer’s directions should always be read to understand how to use a mold fogger. Here are some tips:
Mold fogging can be a great way to remediate mold in your home. However, avoid relying solely on fogging for mold removal.
Fogging is just part of the puzzle and not the only puzzle piece.
Meet the author: Brad Fishbein is an ACAC council-certified Microbial Investigator. In the fall of 2012, he became a Licensed Mold Assessor in the State of Florida through the Department of Business & Professional Regulation. Brad has helped homeowners with over 5,000 successfully completed Mold Inspections since 2009.