Part 5: How Excessive Moisture Affects Your Indoor Air Quality

Cesar Collado
Apr 27, 2022

Don’t… Let the Dust Settle Blog Series

Mold, Bacteria, and Dust Mites Thrive in Moisture 

Last week’s article explained the presence of dust and harmful pollutants in a home and the steps to manage dust. Unfortunately, if you are mold sensitive or allergic, there is no substitute for vigilant “mold hygiene” to keep your air clean. HEPA Air Purifiers are also helpful in alleviating allergic and immune reactions in the areas where you spend the most time (living room, office, or bedroom). However, there are very many sources of indoor air pollution that must be addressed at the source.

There is no replacement for clean, quality air to help the body heal. This article will discuss the various microbial air pollutants caused by excess moisture. Of course, the primary solution to any moisture-related problem is to remove the source of moisture and then remove any moldy or water-damaged materials. Biological pollutants such as bacteria, mold, and dust mites reproduce rapidly as the result of excess moisture. These microorganisms can become aerosolized or become airborne by attaching to dust particles. You must first identify the source of moisture. It can come from roof leaks, storm damage, plumbing leaks, humidity, and areas where condensation occurs (windows, pipes, HVAC components, etc.). After the sources are fixed, you will be able to remove the biological particulates by using tools with HEPA filters (Vacuums, Air Purifiers, or Air Scrubbers). There are many challenges to this task that will be addressed.

EPA: “Four Major Indoor Air Pollutants”

The Environmental Protection Agency has noted that excess moisture, volatile organic compounds, carbon monoxide, and radon are the “Four Major Indoor Air Pollutants”. Volatile Organic Compounds (“VOCs”) are often incorporated into a home through the utilization of chemicals in building materials and home furnishings. There are many toxic chemicals used to make or protect manufactured building materials. Manufactured materials are made by using wood particles as in plywood or paper as in drywall. The pieces are held together through a process that involves machinery and chemicals to make strong, sizable surfaces that are inexpensive and easy to build with. Other chemicals used include sealants and protectants, fire retardants, adhesives, finishes, and cleaning products. These chemicals used in manufacturing will off-gas into the air over time. You can often smell them. For gas pollutants that you may not smell, you can purchase carbon monoxide monitors or radon screening kits to identify the levels of these gases in your home. In these cases, Carbon Monoxide and Radon issues must be addressed by professionals.

While moisture itself is not a recognized indoor pollutant, the EPA declares it as the most common causes of harmful pollutants. DIY Home inspection for moisture is not difficult. Read more about DIY mold inspection HERE. Because microorganisms are ubiquitous, high levels of moisture creates many problems. It can impact an entire building’s health. When moisture meets dust or other organic materials, mold and bacteria can reproduce rapidly. Mold, mildew, bacteria, and dust mites thrive with excess moisture. Mildew, dust mites, and their feces can trigger asthma and other allergic reactions. Some chemicals and mold mycotoxin particulates are very small, and can be inhaled deeply into the lung and sinus tissues. They can be very dangerous to human and pet health. Water leaks and storm damage can increase moisture by spreading throughout a home due to ventilation physics.

These three ventilation effects will spread mold and moisture throughout a home. In fact, water can travel through wood, concrete, along pipes at rapid rates of lengthy distances.

Water Damage is Always Problematic

Water-damaged homes are the single biggest source of toxic mold problems. Here are some interesting facts about water damage:

  • In the US, 14,000 homes suffer from water damage each day
  • 98% of basements will experience water damage in their lifetime
  • 37% of homeowners claim to have experienced water damage
  • Almost all washing machines and water heaters will experience a leak (supply & drain hoses) or failure within 9 years of installation.
  • 250 gallons can leak from a 1/8-inch leak in a water pipe in one day

Another important element to ascertain is the type of damage you are experiencing. Category 1 leaks occur and are referenced as “Clean Water.” Most often it is caused by plumbing overflow and indoor flooding. Category 2 leaks are called “Gray water”. This means that there may be some contaminants in the water. This could be from a construction leak, washing machine, etc. Category 3 Leaks are called “Black Water” leaks. These occur when sewage, floodwater, toilet, or standing waterflood is present. Microbial or other contaminants are likely present. Blackwater leaks can cause severe illness and even death. The classification often determines the level of cleaning and replacement that will be required with remediation.

Common daily activities such as clothes washing activities, showering, and cooking can also contribute to increased moisture, odors, and microorganism growth.

DIY Cold Fogging or Misting

There are two types of fogging processes used to reach large areas with a solution that will eliminate mold from ambient air. Cold Fogging aerosolizes liquids into microparticles and can be effective for ambient air disinfection. These foggers can be adjusted to deliver droplets in the range of 10 to 50 microns in diameter, which have a fall time of less than 15 minutes. When aerosolized, these droplets can be effective by colliding with airborne biological contaminants and breaking the cell wall with an effective solution. The “wet” debris eventually falls to the floor and must be removed by HEPA vacuuming and proper wiping of horizontal surfaces. Proper usage of these foggers requires some knowledge of the home’s airflow. It must also be uniformly sprayed to fog an entire space. The user must be precise in directing the spray into corners and up to the ceiling to reach the entire space in a room. When fogging/misting, the HVAC should be shut off and doors must be closed for 30 minutes to ensure air flows do not dilute the fog/mist. Fogging directly into the return vent of HVAC will provide some treatment in the ductwork and air handler.

Misting is an excellent maintenance step to reduce active mold in the air in your home or on surfaces.

Cold fogging or misting is used in some manufacturing settings for disinfection of products. A cold mist spray in a chamber or conveyor belt will expose all surface areas. Unfortunately, ventilation physics demonstrates that cold fogging does not uniformly distribute the fluid evenly to all surface areas; however, cold misting is ideal for home hygiene maintenance because of the low cost, ease of use, and extended reach of cold fogger aerosolization. Monthly or weekly misting coupled with HEPA vacuuming can help keep mold from getting a foothold to reproduce in amounts that can contaminate the air. In these cases, precision is not necessary or required.

Cold fogging remains an excellent maintenance step to reduce active mold in the air and on surfaces. 1000 sq. ft. can be fogged in a matter of a tens of minutes with minimal effort. I recommend the HavenMist Kit because it weighs only a few pounds. I have used larger misters such as the Dynafog SANI+TIZER: however, it weighs approximately 21 lbs. when full. This weight can be prohibitive to users that may be ill, petite, or elderly.

When mold is confined to a few rooms or areas, misting will reduce mold and keep it under control.

It is strongly recommended that HEPA vacuuming and/or wet wiping with microfiber cloths after cold fogging be done to remove mold debris and mold-contaminated dust. In addition, cold fogging will not address visual mold or staining. Any mold that can be seen with the human eye constitutes millions of spores. In fact, it can be the ‘tip of the iceberg’ if mold is inside a wall and could contain billions of mold spores (or more). This type of mold can be removed if located on a non-porous surface that can be cleaned and scrubbed.


DIY Hot Fogging

 Hot fogging uses heat to create a fog that spreads and rises freely in and out of the airflow. Because the ‘smoke-like’ fog rises, you can see the fog filling the room volume. Additional volume and pressurization force the fog into crevices and any area where air is leaking. For example, a medium-sized fogger may produce 10,000 cubic feet per minute. Let us assume you are fogging a 20 x 30 living area with 12 ft ceilings. That is 7,200 cubic ft (20’x30’x12’=7,200cubic ft). A room this size may require approximately 15 minutes to fill with fog. The hot fogger releases the fog in cycles of 1 minute on and 1 minute off. That would be seven minutes of production so 7 x 10,000 cfm= 70,000 cubic ft of fog. The fog thickens to ~10 times the space occupied. This level of density forces the fog to enter crevices, enter wall cavities, and surround all furnishings to reach all surface areas. The fog will dissipate slowly. The air will clear over a few hours; however, it is best to wait 24 hours to allow any remaining ingredients to fully evaporate.

Hot fogging a classroom where children spend the majority of their time.  

Hot fogging offers many advantages to cold fogging or misting. You can see that high-density fog will fill the entire space. This ensures the fog particles have the ability to collide with bacteria, mold, and dust. The fog is also an agglomerator of particles. This means that the fog particles are social and bind to particulates that ‘stick together to form masses of molecules. These larger groups of particulates will be impacted by gravity and settle onto the floor and horizontal surfaces. The remaining debris can then be removed by HEPA vacuuming or wiping down properly.

The fog will reach all exposed surface areas and penetrate the top layers of furnishings or textiles such as couches and beds and hard-to-reach furnishings such as curtains (front and back). A dense fog ensures saturation without wetness. It is recommended to not be present in the room that is being fogged to prevent slipping, tripping, or other accidents while visibility is low. It is recommended to allow 12 hours to completely settle. The propylene glycol base will have evaporated completely, leaving no residue. Hot fogging is usually done prior to the final cleaning and HEPA vacuuming of all surface areas. The fog functions in the same manner as smoke bombs in plumbing. As the smoke fills the pipes, escaping smoke identifies leaks. In the case of fogging a home, fog leaks can be identified at the source and be repaired prior to expensive damage. This is especially helpful for attic, roof, and HVAC ductwork leaks.

DIY Mold Fogging is NOT Mold Remediation

Mold fogging with a non-toxic product that can reach airborne mold spores is very valuable in removing mold and dust. When the agglomerated debris settles on horizontal areas, it can be physically removed efficiently. However, the removal of mold spores from the air is only part of the remediation process. Any mold must be physically removed. Mold debris or toxic particulates continue to be allergens and toxins. Mold mycotoxins are chemicals and do not die. They are toxic poisons. These toxic chemicals and/or fragments of them remain toxic to human health. The chemicals can be “sticky” and bond with dust to become airborne. Always follow any fogging effort with a thorough HEPA vacuuming and use microfiber towels and mold cleaning solution to wipe down all horizontal surfaces.

Is it Safe to Fog or Mist?

The EPA does not take a position on endorsing or discouraging the use of fogs and mists; but, the Institute of Inspection Cleaning and Restoration Certification, IICRC, makes it clear that fogging cannot be depended on in lieu of mold removal. Very specifically, according to the IICRC S520 Sec 12.1.7 “Remediators should not mist or fog disinfectants or sanitizers in an attempt to kill mold in lieu of source removal.” Again, fogging may be used to eliminate the mold from the air; but that alone does not resolve a mold problem. If the mold debris is not removed, the toxic and or allergic properties of the debris can be equally as dangerous. They must be removed.

However, due to the COVID pandemic, the practice of disinfecting public and high-risk spaces such as airplanes, schools, businesses, physician waiting rooms, etc. has become common. It is incumbent upon the applicators to ensure toxic chemicals such as bleach or other chemical-based cleaners are not utilized. Spraying without removal of the debris is not the most effective means to treat spaces. However, the EPA has endorsed the use of cold foggers and electrostatic sprayers in public spaces that have high-risk exposure potential. Electrostatic sprayers positively charge the disinfectant as it flows through the nozzle. The charged airborne droplets are then attracted to negatively charged surfaces, which allows for efficient coating of hard nonporous surfaces.

Hot Fogging Using HavenFog

HavenFog is the only hot fogging product commercially available for DIYers. It has been used by remediators for over 20 years. Today, a growing number of building science experts utilize hot fogging in the process of home remediation. These professionals have extensive training in building science and mold remediation. They often partner with physicians that treat environmental illness after it is determined that the home is the cause of a patient’s illness. Mold inspectors and remediators can provide mold testing results to the physicians. Conversely, doctors and patients can provide the patient’s level of sensitivity and symptoms. This communication also provides clues to identifying specific molds and their origin. The fog will partially penetrate porous surfaces and textiles including the top layers of upholstery. However, it will not fully penetrate upholstered furnishings or hard surfaces. Therefore, it is recommended that furnishings with mold growing on them be removed.

When mold has effected more than one room, or has been detected with mold tests and is present but not seen, fogging with HavenFog™ will reduce mold and keep it under control.

Hot fogging is the only effective means to systematically remove most, if not all airborne mold spores and debris during the remediation process. HavenFog empowers mold remediators and mold patients to extend their efforts to difficult to reach mold spores in corners, cracks, crevices. You can also open cabinets and drawers to reach surface areas and contents. The unit has a remote switch so that the person fogging does not have to be in the room while the fogger is running if desired; however, direct, minimal exposure to the fog is not dangerous to humans. It is recommended to let the fog evaporate over a 12-hour period. It is also recommended that hot fogging always be followed by HEPA vacuuming and wipe down with a non-toxic cleaner to remove mold spores, toxic dust and debris.

The Wide Use of Fog

Propylene glycol has been broadly used for over a half of century by various industries. It is Generally Regarded as Safe (GRAS) and is widely used in food preparations, medicine, cosmetics, and personal cleaning products. (It is even an ingredient in Mountain Dew.) BioBalance HavenFog has been effectively used by professional remediators for over 20 years. There have been no reports of adverse effects associated with the fogging.

Propylene glycol was first used to create “smoke like” special effects which have been adopted by movie producers, theaters, fire safety and military training, night clubs, and other industries safely for over 50 years. In these cases, people are directly exposed to the fog. The hot fogging innovation was developed by the entertainment industry for special effects during the 1970s. This industry previously used a more volatile solution with dry ice. Gunter Schaidt, Safex Chemie GmbH, one of the preeminent fog machine producers in Germany received an Academy Award in the category of Technology in Cinema (“Oscar”) for “non-toxic liquid for artificial fog” in 1984.

During the 1990s, the Actors’ Equity Association (AEA) and the League of American Theaters and Producers (LATP), worked with the National Institute for Occupational Safety and Health (NIOSH) and investigators from the Mount Sinai School of Medicine to conduct a study to determine whether the use of smoke, haze, and pyrotechnics special effects in theatrical musical productions is associated with a negative health impact in actors. This effort was initiated in response to ongoing concerns by actors that the use of these theatrical effects may have a deleterious impact on their health. The study was extensive. The result of the study concluded that “No evidence of serious health effects was found to be associated with exposure to any of the theatrical effects evaluated in this study.” However, like most consumer products, significant exposure without a respirator can result in respiratory, throat, and nasal irritation as well as dry eyes.

The study, “Health Effects Evaluation of Theatrical Smoke, Haze, And Pyrotechnics” [1], has been revisited and updated several times during the 1990s with the latest version being published in 2020. Since then and during the 2010s, the Agency for Toxic Substances and Disease Registry published “Case Studies in Environmental Medicine (CSEM): Ethylene Glycol and Propylene Glycol Toxicity” which established a toxicity profile of ethylene glycol (Highly Toxic) and also established the safety of propylene glycol as Generally Regarded As Safe (GRAS) for use in food, pharmaceuticals, and cosmetics.

While propylene glycol is NOT a disinfectant, it has been studied and used extensively for its antimicrobial activity. These studies date all the way back to the 1940s [2]. Since then, propylene glycol hot fogging has been adopted as a carrier for cleaning agents. Hot fogging has been adopted by the pharmaceutical industries, hospitals, and food production for cleaning. Prior to fogging, manufacturing equipment required complete disassembly after each use which was time consuming, expensive, and created opportunity costs. Hot fog is also used when cleaning and sanitizing hospitals, clean rooms for manufacturing electronic components, and research labs. Propylene glycol is currently being studied for its effect on viruses because of several recent viral epidemics and pandemics.

HavenFog – Designed for the Chemically Sensitive

While HavenFog uses propylene glycol as a carrier, it is BioBalance’s proprietary blend of citrus seed extracts that is the active ingredient. These extracts are the highest quality natural products produced without any chemicals used during the production process. Because citrus trees can be exposed to pesticides while the citrus fruits were growing, the industry requires that the manufactured extract be tested for trace amounts of chemicals. It is for this reason that BioBalance’s manufacturer is sourced by the food quality, Florida grown citrus fruits used to make juice for consumption. No chemicals are used during the manufacturing of the extract. The finished citrus seed extracts are quality tested for toxic chemicals and chemical disinfectants.

Physical Removal of Airborne Microbes

HavenFog can be used to fill any enclosed space, home, or room. Because it is smoke-like, it can be visibly seen to occupy the entire space. Use HavenFog until the room is opaque. The microscopic droplets in the fog are “social” and attract other airborne particulates. As the fog and airborne particles agglomerate, the combined particulates are weighed down due to the increased size and weight of the agglomerated microbes and gravity. Microorganism debris and other dust particulates will then settle on the floor and other horizontal surfaces. EPA guidance makes clear that killing mold is not enough. It must be remediated. Therefore, HEPA vacuuming and wet microfiber wipe-downs are necessary. Fortunately, microfiber towels are inexpensive and can be machine washed and reused if desired. Disposable Swiffers can also be used for this purpose. Read more about hot fogging HERE.

Don’t Let the Dust Settle

I hope this series of articles has provided you with an understanding of the importance of maintaining your air quality and helped you learn some remedies to address excessive dust and moisture in a home. Dust is a contributor to mold issues that can make for an unsafe environment in addition to dangerous chemicals, microorganisms, and other toxic air particulates that can be inhaled. This by no means suggests that every home needs an indoor air quality specialist to inspect the home. The intended lesson is that dust accumulation is an unnecessary risk in any home. This is especially important for occupants with mold allergies, mold sensitivity, or chemical sensitivities. Occupants with a compromised immune system should be concerned with dusty environments. The best solution is to incorporate “dust hygiene” in your routine cleaning schedule. This includes having an effective HEPA vacuum as well as some convenient vacuuming tools (Stick vacuums and robots) to keep the cleaning process manageable. Thorough dusting with proper cleaning materials is also important. Waiting until the dust accumulates is not the best strategy. I leave you with one certainty, where there is dust, there is likely mold. Any moisture issue including plumbing and roof leaks, water damage, or condensation can lead to microorganism reproduction and a potentially harmful environment.

I would also like to thank BioBalance for the opportunity to post these articles to reach homeowners and mold sensitive occupants to become vigilant when it comes to indoor air quality and its impact on human health.

  1. Moline, Jacqueline MD et. al, Department of Community and Preventive Medicine Mount Sinai School of Medicine. “Health Effects Evaluation of Theatrical Smoke, Haze, And Pyrotechnics”. Equity-League Pension and Health Trust Funds. June 6, 2000.
  2. Robertson, O. et. al. “The Bactericidal Action of Propylene Glycol Vapor on Microorganisms Suspended in Air.” Journal of Experimental Medicine. June 1, 1942.
  3. Magari, Shannon R. ScD, MS, MPH et. al. “Theatrical Fog Exposure Assessment Methods, Exposure Limits, and Health Effects – Literature Review”. Prepared by Colden Corporation for Contract Services Administration Trust Fund (CSATF). 2017.