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Why Fogging For Mold is a Bad Idea

mold growth on drywall

During the week, our company received two nearly simultaneous calls about situations involving mold remediation where fogging was used as the primary method of removal. One of these prospective clients mentioned that the fogging was ineffective and there was still residual fungal growth present. The other noted that their spouse developed a palsy after the chemical was used and can no longer reside in the residence. In this blog, we will discuss why fogging is not recommended for routine mold remediation projects.

What is Fogging?

Fogging refers to the method of using an antimicrobial pesticide in an aerosolized form in order to kill mold present in a property. While mold remediation isn’t as regulated as other forms of environmental cleanup such as asbestos or lead abatement, there are organizations who set industry standards and guidelines. The Institute of Inspection Cleaning and Restoration Certification (IICRC) produces and maintains a consensus-based standard and the Environmental Protection Agency (EPA) wrote a remediation guideline. The IICRC states that vapor based antimicrobials have not been shown to be able to effectively and safely be used for remediation. The top issues with using the chemicals in this manner are the delivery of the antimicrobial, efficiency, and the potential toxicity of the compounds being utilized. The EPA does not recommend using this method unless the product is registered for that specific purpose.

When Can Fogging be Used?

The EPA defines antimicrobials as chemicals that are used to suppress or destroy microorganisms. These materials are registered and regulated by the EPA’s Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and while not a federal requirement, some states even require licenses for those who apply them. There are also other international organizations such as the European Union that regulate the use of these antimicrobials.

These compounds should only be used for their registered purpose and improper use can affect or harm humans and also pets and wildlife. The product registration describes when the product should be used, what surfaces are allowed, if there are any location restrictions, the proper PPE (Personal Protective Equipment), and conditions the product should be applied in. The chemicals released from antimicrobial products can cause a wide range of health effects depending on the compounds present and the amount of ventilation in the work area.

How then should I kill the mold?

The attraction to fogging chemicals for mold remediation is that the aerosolized antimicrobial can kill mold in a property without having to physically go to each area and remove the fungal growth. Many companies state how their products are effective at killing the mold. While these statements may be truthful to an extent, it doesn’t actually solve the problem. While killing the mold would stop it from propagating, killing it does not take away their allergenic or toxigenic properties which will still be left around after the products have been used. The IICRC recommends that fungal growth be physically removed instead of being simply killed with an antimicrobial product. When mold with its allergenic proteins is in the dumpster outside, it doesn’t really matter if it is dead or alive.


In conclusion, fogging may be able to “kill” mold throughout a property, but it may lead to other unintended consequences. Antimicrobial fogging should only be used in the manner that its EPA registration requires. In fact, it is a violation of federal law to deviate from the labelled instructions! Improper usage may lead to indoor air quality concerns related to the pesticide compounds present in the products. Also, killing the mold does not constitute proper remediation, as the mold growth must be physically removed as killing it may leave behind spores that cause allergic or toxigenic responses.

If you have a remediation contractor suggesting fogging, consider hiring Indoor Science to write out a remediation plan that follows the industry standards and guidelines.  To learn about other common problems we see in remediation, here is another great article on common problems with remediation.

Jordan Thomas

Jordan Thomas

Jordan Thomas is a Project Manager that performs indoor air quality assessments with a specialty in asbestos and lead. Mr. Thomas holds a Bachelors of Arts degree in Earth Science from DePauw University. Jordan is an ACAC Council-Certified Indoor Environmentalist (CIE), Licensed Lead and Asbestos Inspector, Licensed Air Sampling Professional, and HAZWOPER certified. He also holds an asbestos microscopist certificate from the McCrone Research Institute. Prior to working at Indoor Science, Jordan worked as an Industrial Hygienist at Environmental Analysis, Inc and as an Asbestos/Lead Analyst at Metro Technology Laboratory. In his words… “While not in the field, I’m a Nu-Jazz and movie enthusiast.”

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12 thoughts on “Why Fogging For Mold is a Bad Idea

    Mold spores are hydrophobic (like Teflon), meaning they repel or fail to mix with water. Anything water-based will not stick to water droplets, so fogging a water-based product (with or without a pesticide) will have very little effect.


    My parents apartment if literally filled with mold. It’s everywhere due to water damage and the air conditioner not working properly .Its on the walls,carpets,appliances, bedding, furniture, etc.
    A “dry” fogging was recommended called InstaPure. I was told this is completely different from other fogging as this is a gas and non toxic and will penetrate the walls. After the fogging with InstaPure and second step is taken using a product called EverPure. This kills any new mold spores.
    Have you ever heard of this method and what are your thoughts?
    Thank you.


    The purpose of mold remediation is not too kill the mold but to physically remove it. We generally do not recommend antimicrobials under most circumstances as dead fungi can still be problematic for those who are sensitive to it.

    We discovered that our finished basement has had a pin hole water leak from a pipe that goes to our water line for a long time resulting in rotting wood and mold accumulation in one corner of our basement. But we also found mold accumulation on the back of our wooden bookshelves and pictures we had on the wall in the same area. Our contractor came in and repaired the pipe, removed the rotten wood, put in new drywall, repainted the walls and baseboard, and installed new carpet padding and relaid the carpet in that one corner of the basement.
    The contractor said we should throw out our bookshelves and re-carpet the entire basement.
    Can we avoid the hassle of doing the above by dry fogging the entire house? If so, how do we know the chemical used will be ok for our health and should we be concerned about any toxins that will be emitted?
    Please advice,

    We would recommend contacting a consultant in your area to conduct an indoor air quality assessment in your rental. You can find professionals in your area by going to

    Hi. I moved some household goods from a house where there was high humidity because of proximity to the ocean; the house was closed up for 2-3 months per year. The new place is much dryer with much better airflow. However most of the goods (LPs in their jackets, videos, jigsaw puzzles) were arranged in one small room (9X12) with only one register that isn’t serviced very well by the HVAC system, although the rest of the house is OK. 5 years later and the smell of mold/mildew in this room can be overwhelming mostly in the hot, humid summer months. There is NO visible mold or mildew anywhere and I have my house professionally cleaned every two weeks. I have upper respiratory disease where my airway reacts with mucous and inflammation to everything, although I have no allergies, and I am sure this room is making my disease worse. I am 66 and due to COVID I don’t allow anyone in my house except my cleaners who all wear masks, as do I or I leave the house entirely and go to a park. So a DIY solution is my only option. I was considering fogging this room. I would welcome your perspective.

    Hello Heather,

    I would recommend having the house assessed by an indoor air quality professional to determine the source of the odor as it may be related to things that are not apparent to the naked eye.

    Had flood damage under my kitchen and dining room area. The remediation company had to pull up our ceramic tiles but left the sub floor. They removed damaged Sheetrock from the area. There was only a small square opening in our kitchen floor that accessed the contaminated area. The remediation company sprayed a mist into the area for 3 to 4 minutes. My wife and I were in the room. When expressed concern the worker said it’s a safe cream based product. They never went into my crawl space that adjoins the flooded area shuck had mold also. They said the fans they installed would spread the fogging agent everywhere. I pretty much felt my intelligence insulted by being told 4 minutes of misting would kill mold that was in our subfloor and floor joists.


    Hello my name is Thomas Brooks. While searching for information about Chemicals used in a process called, “Fogging.”
    I found you. I live in Ann Arbor Mi, I moved here from L.A. after my dad passed 4 years ago. I have a small family, my only sibling and I decided I would move back to Mi, help our mother sell the family house and support her emotionally. We sold the house and moved my mother and I into a high end apartment community. I became very ill, the present of a harmful black mold was tested and we were told by the Environmental Agency that the condition of the unit was uninhabitable and we move into a hotel the next day, with our dogs and were told to leave all our belongings. Prior to us vacating, the management asked us to vacate the unit for 48 with our dogs. When we return there was a thin layer
    of a whitish dust-like residue coving the granite in the master bathroom where this ( chemical?) was released into the air.
    The residue also covered an old family dresser that was in the hallway adjacent to the master bathroom. I was concerned about the small dogs, the unit had Carpet in all the rooms and I spent several hours steam cleaning the carpet
    and removing the residue. That was 2 years ago. My dog passed away a month later, after we moved while we were living in the hotel. Her esophagus was torn and damaged, her stomach filled with blood and caused her death. I found my mom a new place to live. While visiting her recently I noticed the old family dresser in the dining room and asked her if I could paint it. It was the only item we moved. We bought all new furniture due to the mold. I had a friend help move the piece into the garage to paint, and when I pulled out the drawers, the same white residue covered the shelf that the drawers sit above. We did have the dresser professional cleaned. I contacted the agency who tested the air in our unit. I want that substance tested. I have e-mailed back and forth with the owner of the company, he explained to me that he needs to know what chemical they are testing for? Or it becomes very costly and time consuming. My mom and I were told that ( Mold Specialist) were arriving to solve our toxic living situation but later we learned, that the management hired painters. I want to know what was sprayed. I have read all about “Fogging.” And understand it, how can I prove it? The results from my blood tests show levels as high as 89.4 percent of toxicity from the mold. I have many Health issues due to this but I have a great team of doctors and and am blessed to have the funds available to take care of myself. I certainly appreciate any advice or comment. Sincerely, Thomas Brooks

    Hello Thomas,

    The problem with fogging is the VOCs it releases. VOCs tend to off-gas typically within weeks or a few months. Is there is any residue remaining it has likely off-gassed, however, I would contact an indoor air quality professional in your area to assess the situation. You can find these individuals at and can search for professionals by your zip code. The professionals would have a CIE or CIEC certification on the site.