Left untreated, mold growth can cause significant health problems for a home’s occupants, with women, children, the elderly, the immunocompromised, and persons with allergies being among those at the highest risk of adverse events.1U.S. CDC, Mold After a Disaster, accessed Mar. 27, 2023 2Rhode Island Department of Health, Mold Health Risks, accessed Mar. 27, 2023
So-called “mold foggers” are devices that emit a cloud of aerosolized chemicals (or botanicals) apparently designed to treat mold concerns, such as by allegedly inhibiting the growth of mold spores, or by merely grounding the microscopic spores so they can then be cleaned off the surfaces they land on.
These are fundamentally flawed concepts.
- Mold foggers will not solve a mold problem, no matter how small.
- Mold foggers may be used as one part of professional mold remediation.
- Consumer mold foggers (in “spray-paint style” cans) are likely to disappoint, and do very little or nothing to resolve a mold problem.
- Mold foggers can provide a false sense of a solution, or of having done something to treat mold.
- Mold foggers can cause their own unique indoor air quality concerns.
- Some companies “prey on customers” by offering “demolition-free mold remediation done with fogging devices,” in violation of even the US CDC’s advice on mold, as well as the advice of major national mold remediation professional bodies.
- Not all fogging is bad, but fogging without removing and remediating the mold is always bad.
Mold foggers fall into two categories and price ranges: Professional devices cost $250-$500 and are reusable, while consumer devices cost about $40-$60 and are not reusable. Consumer devices come in cans similar to spray paint.
Mold foggers are a commonly discussed treatment for mold growth.
Are they also an effective one?
In short, no.
- Consumer mold foggers are entirely useless as a treatment for a mold problem.
- Professional fogging may play a small part in some mold remediation work, but not all remediation pros agree on the need for or effectiveness of fogging.3The earliest and still highly regarded guidance on mold remediation, The New York City Guidelines, suggested against fogging; more recent Guidance still suggests against fogging, but notes a lack of consensus among remediators on the subject: Nearly all trained mold remediators do agree that fogging alone is never considered proper remediation.
- Professionals who suggest that fogging alone is a proper mold treatment should be avoided.
Some foggers work as intended, but not much is intended to begin with.
Some mold foggers work as intended, but no mold fogger is intended as the solution to a mold problem.
If mold is present, the source of moisture or water must always be located and corrected (leaky pipes, bathtub seals, etc.), and the moldy porous material must be completely / properly removed (drywall, carpeting, stuffed animals, couches, cushions, insulation, wallpaper). Wood beams can be wire brushed and treated with fungicides, and non porous items can usually be cleaned and kept.
So what purpose does a mold fogger fulfill?
According to information provided by the manufacturer of the most popular consumer mold fogger, their purpose is to ground airborne particulates (such as mold), in order to make clean up easier. They are a “particulate suppression” system, and one that isn’t effective on living (viable) mold spores.
In other words, this aerosolized solution of various chemicals goes airborne and connects with microscopic mold spores and other particulates, which it then weighs down, causing them to drop down onto various surfaces in the room.
When the mold spores have apparently been grounded, they should be wiped up.
Again, these are fundamentally flawed concepts.
Mold Foggers: Insight From Experts
Fogging as a method of mold remediation or removal has been disadvised since the earliest and still most renowned guidelines on mold remediation, colloquially known as ‘The New York City Guidelines,’ (see no. 1, below.) Summarized below are what it as well as other well-known names in the industry have shared on fogging.
Fogging…is not recommended.
“The use of gaseous, vapor-phase, or aerosolized (e.g. fogging) biocides for remedial purposes is not recommended. Using biocides in this manner can pose health concerns for people in occupied spaces of the building and for people returning to the treated space. Furthermore, the effectiveness of these treatments is unproven and does not address the possible health concerns from the presence of the remaining non-viable mold.4“New York City Department of Health and Mental Hygiene, “Guidelines on Assessment and Remediation of Fungi in Indoor Environments,” Nov. 2008
Fogging for mold is ‘not a good idea.’
“Can we do fogging as a standalone process? The answer is No.” “…they literally come in and they fog your house and think that’s going to get rid of the mold spores. And it doesn’t. All it does is suppress those mold spores. You could actually be pushing them in different places. It’s just not a good idea to do that as a standalone process,” says Steve Worsley of CNC Contractor Services. 5Steve Worsley, The Toxic Mold Podcast, Episode 131, “Fogging and Spraying Black Mold. Is That a Bad Idea?,” Nov. 8, 2021
Fogging ‘does not eliminate mold by itself.’
Mold expert Michael Rubino of HomeCleanse.com writes that “demolition-free mold remediation” is an “elephant in the room” as far as the quality of mold remediation. “When I see this phrase, I cringe.” Rubino goes on to state that nowhere in professional guidelines does it say remediators should fail to remove drywall and other wet material during mold remediation. Rubino suggests contractors who provide so-called demolition-free mold remediation are either uninformed or are preying on people who know no better.6Book: The Mold Medic, An Expert’s Guide on Mold Removal, by Michael Rubino, Self published © 2020
Elsewhere, Mr. Rubino calls dry fogging “a low-cost, band aid solution to your mold problem,” which “does not eliminate mold by itself.”7MoldCleanse.com, “Does Does Dry Fogging Eliminate Mold,” by Michael Rubino, May 12, 2021
Fogging is a remediator ‘red flag.’
Author and longtime mold expert Daniel Stih of HealthyLivingSpaces.com says people trying to solve a mold problem at home should avoid companies that try to “treat mold,” instead of removing it. “Walk away from a company that uses or has any of the following words in their estimate,” says Stih, who lists antimicrobials, disinfectants, and bleach as bad signs to see from a mold remediation company. Mold should be removed from a property, not “killed,” and not “treated.” An example given by Stih concerns fogging and atomization specifically.
Stih lists this example advertisement as one of many remediation red flags: “Kill The Mold: Disinfection and sterilization of entire attic via fogging / atomization with a disinfectant to kill airborne spores….” 8Book: Mold Money, How to Save Thousands of Dollars on Mold Remediation and Make Sure the Mold is Gone, by Daniel Stih, Healthy Living Spaces © 2015
Some mold remediators ‘over-rely’ on antimicrobials.
Prolific author, course creator, and mold training specialist Ian Cull of IndoorSciences.com says, “Unfortunately, some remediation contractors over-rely on antimicrobial chemicals to the detriment of source removal. It is worth emphasizing that antimicrobial chemicals should not replace source removal.”9Book: Fundamentals of Mold Remediation, by Ian Cull, Indoor Sciences, Inc. © 2017
So Are All Mold Foggers Garbage?
Yes, consumer mold foggers, which are usually bought in spray-paint style cans are ineffective, and are often very poorly rated by even the most hopeful consumers.
They promise to do various things such as “kill mold,” but elsewhere say the product is actually intended for use only on non-living spores. (Never mind that killing mold is a ludicrous idea.) And that the mold fogger is actually just one part of a (rather costly) three-step process of proper mold removal. And that its only actual purpose is to ground mold particulates so they can be easily cleaned off of the surfaces they land on.
Professional mold foggers are a different story: They are either ineffective (if used alone and without any needed demolition and remediation being done), or effective (if used as one of many ways to clean any remnant mold spores and other particulate matter out of the air.)
These two uses — consumer versus professional — are so incredibly different. It isn’t just a matter of “more fogging good so need big fogger.” It’s that properly done mold remediation includes so many factors that just aren’t present when you buy and use a mold fogger or mold bomb.
Among these, in proper professional mold remediation:
- Sources of water or moisture have been found and fixed.
- Negative air containment and floor-to-ceiling barriers have been put up, preventing mold from traveling around the house (as much as is possible.)
- Wet building material has been physically removed. Porous items have been tossed, non porous items have been treated. (Parts of a home may have to be gutted.)
- Air scrubbers are run in the space.
- HEPA vacuums are run in the space.
A “consumer” mold bomb or mold fogger omits every one of the above items. They are not an effective way to treat a mold problem of any size.
Alternatives to Mold Foggers
The alternative to a consumer mold fogger is proper mold remediation, if it is needed.
The alternative to a contractor who wants to fog your home and call it a day, is a NORMI-certified mold remediator who actually knows what he or she is doing—and knows that fogging alone is never effective.
- Standard Mold Remediation: Proper mold remediation followed by thorough air scrubbing and the use of antimicrobial chemicals is an acceptable replacement for (or use of) mold foggers.
- HEPA Vacuuming: High-Efficiency Particulate Air (HEPA) vacuums can help remove mold spores from surfaces and improve air quality. These vacuums are designed to capture even the smallest mold spores, preventing them from becoming airborne and spreading throughout the space.
- Surface Cleaning: Physically cleaning the affected area with appropriate cleaners and biocides can be more effective than fogging, especially when it comes to removing mold from hard surfaces. This method often involves scrubbing the surfaces with brushes or other tools to remove the mold completely.
- Air Purifiers: Using air purifiers equipped with HEPA filters can help to remove mold spores from the air, improving indoor air quality.
Since mold foggers do not remove mold, nor locate the source of moisture that caused the mold concern to begin with, they are ineffective if used alone. At best, they can provide a very false sense of safety, and at worst can cause additional indoor air quality concerns.
Mold foggers can be an acceptable part of a full professional mold remediation process, but they should only ever be used in conjunction with proper mold remediation.
(If you feel you need to use water-based mold prevention products in an apartment or home you are leasing, it’s usually in your best interest to report the mold concern to your landlord.)
- 1U.S. CDC, Mold After a Disaster, accessed Mar. 27, 2023
- 2Rhode Island Department of Health, Mold Health Risks, accessed Mar. 27, 2023
- 3The earliest and still highly regarded guidance on mold remediation, The New York City Guidelines, suggested against fogging; more recent Guidance still suggests against fogging, but notes a lack of consensus among remediators on the subject: Nearly all trained mold remediators do agree that fogging alone is never considered proper remediation.
- 4“New York City Department of Health and Mental Hygiene, “Guidelines on Assessment and Remediation of Fungi in Indoor Environments,” Nov. 2008
- 5Steve Worsley, The Toxic Mold Podcast, Episode 131, “Fogging and Spraying Black Mold. Is That a Bad Idea?,” Nov. 8, 2021
- 6Book: The Mold Medic, An Expert’s Guide on Mold Removal, by Michael Rubino, Self published © 2020
- 7MoldCleanse.com, “Does Does Dry Fogging Eliminate Mold,” by Michael Rubino, May 12, 2021
- 8Book: Mold Money, How to Save Thousands of Dollars on Mold Remediation and Make Sure the Mold is Gone, by Daniel Stih, Healthy Living Spaces © 2015
- 9Book: Fundamentals of Mold Remediation, by Ian Cull, Indoor Sciences, Inc. © 2017