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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.

Ian Cull

Ian Cull is a nationally recognized expert in the field of indoor air quality. He is the Chief Science Officer of Indoor Science, a company he started in 2004. He speaks around the world on air quality topics and is a training provider of the Indoor Air Quality Association. Mr. Cull is a Licensed Professional Engineer (PE) and Certified Industrial Hygienist (CIH). His degree is in Environmental Engineering from the University of Illinois - Urbana Champaign. Mr. Cull has developed 50 air quality related courses for the IAQA University and is the author of the book, “Fundamentals of Mold Remediation”. In his words… “Besides being passionate about indoor air quality, I enjoy cycling, music, the Chicago Bulls, and having fun with my three kids.”

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

    I live in Del Mar, CA and have a mold problem in a 690 sq ft apt.
    The construction is all wood. I had thought the Fog process might be the answer, but after research it looks like a highly dangerous substance.
    Can you help me with safe effective options and to find a company that uses these?

    Hello Alice,

    I would recommend using the acac.org to find a professional in the area to elevate the fungal growth. I would make sure that the professional uses IICRC S520 guidelines when removing the fungal growth. Typically mold growth on wood is removed by using abrasive methods such as wire brush and sandpaper usually in a contained space.

    Thank you. This answered some of my questions. Do you happen to know anything about air scrubbers? Our issue is moving from a house with mold to one with no mold issues. I read spores can attach to just about all of our belongings. I am looking for a somewhat manageable way of “cleaning” our belongings once we have moved in order to prevent starting a mold problem in the new place.

    We have a 3000 sq ft home that recently bought and just experienced water damage from an ice dam. Prior to that, I had a haunch that we had a mold issue (the house is 100 yrs old) so I had contracted a mold abatement company to come in. They were able to tackle the new water damage issue in a timely manner, which was great. The mold abatement is a bit more concerning to me. Air quality testing showed mold in the basement, and possibly converted attic space. We found the top floor bathroom vanity and radiator both had slow leaks and the floor rotted over time. The demo went fairly well until they found black mold on the baseboards. It was the end of the day, and the contractor was in a hurry to finish up. He had a scrubber on for the demo, pulled out the baseboard, but then left without treating the area, and turned off the scrubber for the night! The area is not contained, and because we have so many open walls, with fans blowing…I’m afraid we now have black mold spores everywhere. I could really use your guidance for how to test and remediate from our remediation!!

    I believe I had water damage at a pervious apartment. Mold spores develop and got on my belongings. I took my belongings to another apartment and now I’m currently dealing with mold spores. I had an air quality test done and I’m dealing with Stachybotrys spores and Penicillium/Aspergillus spores. I rent an apartment and my apartments won’t help me. How can I get rid of this? Do you know of a good mold remediation company in Denver Colorado? Please help me and my family.

    Hello Monique,

    I would search for consultants in your area you use ACAC.org and search for mold professionals.

    I live in a mobile home and for the first time since moving there in 2007, I am having a large bloom of white mold.
    I am having someone in the remodeling / construction business come in, in an attempt to identify and address the source of the moisture.
    According to Home Advisor, the cost of mold remediation and removal is between $10 to $25 per square foot.
    My home is 850 SF, making professional mold remediation and removal cost prohibitive.
    I don’t appear to have a sensitivity to the mold, but I suspect that may change as the bloom worsens.
    I was thinking about parking a used travel trailer on the property to live in temporarily and deploying a Concrobium fogger to at least arrest the bloom and give me enough time to extricate and remediate valuables and items with sentimental value, while throwing most everything else out.
    I don’t know what else to do and I am open to suggestions.

    Hello Mark,

    I recommend having a mold professional who doesn’t do remediation inspect the property to determine the source of the growth. I would recommend locating the source of moisture in the home by using a moisture meter on the area where mold is present to see if it is damp. I would also recommend checking the relative humidity using a hygrometer. The humidity in the home should be 30-60 in warmer months and below 35% when temperatures are below freezing. A HEPA purifier may capture spores in air also.

    I have a 1100 sq ft condo on the Gulf Coast (St Pete) that I purchased in July of last year, it was built in 81. The A/C unit is at least 20 years old and apparently not very efficient. It was vacant most of last summer and the A/C was kept at 78 degrees and there were zero issues. I’ve been gone since late March due to Covid and left the A/C at 78 again. All water was shut off so there’s no leaks. We just returned today and found light spotting on the fridge, mirrors, dresser and chairs etc along with a heavy mildew odor. The issue is obviously caused from a poor efficiency A/C unit which should have been set lower. Do these items need to be thrown out or would a good cleaning with white vinegar or something else be a good solution? Do I need to worry about furniture and mattresses? A search for an air quality specialist did not turn up much. My wife is 120 days past a stem cell transplant so I don’t have time to fool around. Thanks for any suggestions you can provide!

    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.

    I did it and regret it and having severe lung, sinus, breathing, eye issues and many other medical issues. I looked up what is in both products since the smell will not go away and my health is getting worse. There are so many hazardous things in their product, so many side effects, I am horrified it is allowed to be used. The smell was supposed to go away after 36 hours, day 5 now and if I could afford it, I would move to a hotel. Owner of the franchise could care less since I have yet to hear from him, only the office manager.

    I was not dealing with the visible mold, mostly mildew, that smell has lessened but still present over the toxic fumes. Next step it appears is to contact the main office in Utah since my home is almost not livable. If you have allergies or lung issues as I do, FIND ANOTHER OPTION! Ask them for the safety data then look them all up, make your decision about how non toxic it is, especially the hazard data.

    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,

    In Hawaii-sll
    Mew rental s full of mold. What do we do first line of defense as tenant with sensitivities?

    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 iaqa.org

    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 acac.org and can search for professionals by your zip code. The professionals would have a CIE or CIEC certification on the site.