Mold Remediation

For spaces found to be “moldy” (i.e., water-damaged, regardless of the findings on testing, when used), remediation by certified personnel is recommended. Improper efforts can spread microbes (such as mold, bacteria and parasites), spores, fragments and toxins throughout the entire structure as water-damaged building materials are removed. As such, in many cases, occupants should be relocated during the remediation process.


Because many factors must be considered when remediating water-damaged homes, schools, offices and other buildings, and because there are several industry guidelines and government publications about remediation, it is not practical to provide a detailed discussion of mold remediation in this paper. However, we will be discussing a few key topics relating to remediation. 


It is important to state there are some water damage situations that cannot be resolved or corrected with remediation, and remediation is not always successful. 


If remediation is attempted, proper containment procedures and personal protective equipment are critical, because disturbing or handling the contaminants can result in increased aerosolized spores and particles containing mycotoxins which can be dangerous to human health and destructive to property.


Personal Protective Equipment (PPE)


During remediation or renovation of water-damaged structures, personal protective equipment (PPE) should be used to protect the occupants and workers.

 

  • Protective clothing that covers the entire body (i.e., a disposable body suit such as TYVEK with mold-impervious, disposable head and foot coverings). All gaps in the clothing, such as those around ankles and wrists, should be sealed.
  • An N-95 respirator or better (i.e., a half-face or full-face respirator with N, R or P100 filters). Filters should be replaced after each use.
  • Protective gloves (made of natural rubber, neoprene, nitrile, polyurethane or polyvinylchloride). Do not touch mold or moldy items with bare hands.
  • Non-vented goggles. Wear goggles that provide complete eye protection. Choose goggles designed to keep out dust and small particles. Safety glasses or goggles that have open vent holes will not protect you against dust and small particles.

 

The U.S. Centers for Disease Control and Prevention (CDC) provides the following guidance regarding personal protective equipment (PPE):


Primary functions of PPE in a mold-contaminated environment are prevention of the inhalation and ingestion of mold and mold spores and prevention of mold contact with skin or eyes.


Respirators used to protect persons from airborne contaminants (including mold and mold spores) must be certified by CDC's NIOSH. In addition, as specified by the OSHA respiratory protection standard, workers whose employers require them to use respirators must be properly trained, have medical clearance, and be properly fit-tested before they use the respirator. Formal fit testing is recommended for anyone engaging in remediation work causing extensive exposure to mold.


Persons doing remediation work that involves extensive exposure to mold should have respiratory protection greater than that provided by a NIOSH-certified N-95 respirator. Full face-piece respirators that have NIOSH-certified N100, R100, P100 particulate filters are recommended.


The processes involved in accomplishing effective mold remediation are dependent upon multiple factors as each water damage situation presents its own unique set of circumstances and challenges. For example, because some water-damaged structures may produce a false negative test result based on sampling, remediation procedures should still be implemented.


It is important to note that remediation plans should not be prepared by the person or company who will be doing the remediation work. There needs to be a separation of duties in order to ensure proper procedures and industry guidelines are outlined in the remediation plan and to avoid any conflict of interest.


Mycotoxins routinely travel with spores (alive or dead) and, even more concerning, travel with very small, even submicron-sized particles capable of penetrating deep into the lungs. At this level, they are subjected to the effects of pulmonary surfactants which allow otherwise insoluble toxins to be absorbed into the bloodstream. And, as mentioned earlier in this paper, mycotoxins can cross the blood-brain barrier.


A report by the U.S. Department of Housing and Urban Development (HUD) discusses molds and mycotoxins, as follows:


Many molds are also known to produce mycotoxins, which are toxic metabolites that can be a health hazard to birds and mammals upon natural exposure, i.e., ingestion, dermal contact, or inhalation. While common outdoor molds present in ambient air, such as Cladosporium cladosporioides and Alternaria alternata, do not usually produce toxins, many other different mold species do.


Genera producing fungi associated with wet buildings, such as Aspergillus versicolor, Fusarium verticillioides, Penicillium aurantiogriseum, and Stachybotrys chartarum, can produce potent toxins, measurable in mold mycelia, spores, and the matrix in which the mold is growing. A single mold species may produce several different toxins, and a given mycotoxin may be produced by more than one species of fungi. Furthermore, toxin-producing fungi do not necessarily produce mycotoxins under all growth conditions, with production being dependent on the substrate it is metabolizing, temperature, water content and humidity.


Some experts suggest creating a “safe room” in a moldy dwelling for those who cannot afford to properly remediate the entire space and also thoroughly cleansing pets and vehicles with natural (non-chemical) products. Safe rooms are created by positively pressurizing a room and using HEPA air purifiers.


The 2013 report from the U.S. National Institute of Occupational Safety and Health (NIOSH) provides good general advice: “Building owners and employers should always respond when occupant health concerns are reported.” 


The NIOSH report offers the following words of caution:


Renovation (and remediation) projects can create the release of airborne dusts, microbiological contaminants, gasses, and odors from both inside and outside of a building. Therefore, careful planning is essential to prevent exposures to building occupants. Key factors to consider include scheduling projects during times of low or non-occupancy, isolating work areas from occupied areas using temporary barriers, negative pressurization to prevent migration of air contaminants into occupied areas, and HEPA filtration.


Inappropriate remediation (e.g., painting over water-damaged materials, adding air-fresheners in areas to mask musty odors, and applying disinfectants or biocides to damp or moldy surfaces) can cause further problems with building degradation and symptoms in occupants.


In the 2012 study by Peitzsch et al, researchers tested ten commonly used agents purporting to be capable of neutralizing mycotoxins and/or suppressing mold growth; not one of them completely removed all mold and toxins. The report states (in part):


We compared the efficiency of some commercially available products and methods used for remediation of mould-contaminated building materials. Samples of gypsum board and pinewood were artificially contaminated with toxin-producing isolates of Stachybotrys chartarum and Aspergillus versicolor, respectively, then, ten different remediation treatments were applied according to the manufacturers’ instructions. Microbial and chemical analyses of the infested materials were carried out both immediately before and after treatment, after six weeks of drying at room temperature, and after another six weeks of remoistening.


The aim of the study was to determine whether the investigated methods could inhibit the mould growth and destroy some selected mycotoxins produced by the moulds. None of the decontamination methods tested could completely eliminate viable moulds. No remediation treatment eliminated all the toxins from the damaged materials. These results emphasize the importance to work preventatively with moisture safety throughout the construction processes and management to prevent mould growth on building materials.


Another paper published in 2018 showed that employees in a large office building continued to have respiratory and non-respiratory effects even after multiple remediation attempts. They summarized their findings as follows:


Our study indicates that once respiratory or severe non-respiratory symptoms have developed from long-term exposure to dampness and mold, the symptoms might not be easily improved despite various remediation activities. Our findings suggest that in moisture-damaged buildings with sentinel cases of building-related lung disease, the best public actions would be prompt relocation of affected employees, which might prevent further exacerbation of their illness or prompt remediation once water leaks are identified, that is before respiratory and severe non-respiratory symptoms have developed in building occupants.


Building owners, homeowners and others responsible for the proper maintenance of structures are encouraged to contact experienced, knowledgeable and certified professionals for appropriate guidance. As mentioned above, it is not practical to provide a detailed discussion of mold remediation in this paper. However, we are going to provide a few brief comments about HVAC systems, ducts and biocides.

Global Indoor Health Network - Mold Remediation

Mold remediation and 
personal protective equipment

Global Indoor Health Network - Mold Remediation
HVAC Systems and Ducts

HVAC (heating, ventilating, and air-conditioning) systems and ducts are common topics in regard to remediation of homes and buildings with mold contamination. As mentioned above, there are some situations that cannot be remediated. HVAC systems are difficult because there are many parts and because it is used to move air through the structure.

In addition, as the Peitzsch study concluded: “None of the decontamination methods tested could completely eliminate viable moulds. No remediation treatment eliminated all the toxins from the damaged materials.”

And, a 2018 study showed that occupants of a large office building were still having symptoms even though there had been repeated attempts to remediate.

Our findings suggest that in moisture-damaged buildings with sentinel cases of building-related lung disease, the best public actions would be prompt relocation of affected employees, which might prevent further exacerbation of their illness or prompt remediation once water leaks are identified, that is before respiratory and severe non-respiratory symptoms have developed in building occupants.

There are several papers and guidelines from government agencies regarding the remediation of HVAC systems. To give you an idea of the contaminants that can be found in HVAC systems, the following description is from a 2015 paper regarding the investigation of dust loading and culturable microorganisms of HVAC systems in 24 office buildings.

To investigate the dust loading and culturable microorganisms contamination characteristics of HVAC systems in 24 office buildings, a series of field tests, which included temperature, RH, air velocity, dust loading, culturable fungi/bacteria loading, were conducted in the following: return air, fresh air, mixture air, cooling, and supply air segments. There were significant positive correlations between dust and culturable fungi loading, dust and culturable bacteria loading, culturable fungi number per gram dust and RH, bacteria number per gram dust and temperature (p < 0.05). Results of these field measurements indicated that dust accumulation and/or high humidity and/or temperature should be properly controlled in HVAC systems to prevent the growth of culturable fungi and bacteria.

A related topic is whether you should have the ducts cleaned. The U.S. EPA says you should consider having your HVAC ducts cleaned if:

1) there is substantial visible mold growth, 
2) ducts are infested with vermin, or 
3) ducts are clogged with excessive amounts of dust and debris and/or particles are actually released into the home from your supply registers.

The EPA also says that service providers should follow the air duct cleaning standards set by the National Air Duct Cleaners Association (NADCA).

The NADCA says homeowners should consider having the HVAC ducts cleaned if: 

1) there are smokers in the household, 
2) there are pets that shed high amounts of hair and dander, 
3) there is water contamination or damage to the home or HVAC system, 
4) there are residents with allergies or asthma, or 
5) after home renovations or remodeling or 
6) prior to occupancy of a new home

It is important to keep in mind that contamination is not just “visible” mold, but it also includes “invisible” particles that can be in the HVAC system which means they can be airborne throughout the building.

Biocides (including bleach)

Another common topic regarding remediation of water-damaged buildings is whether bleach or other biocides should be used. The answer is No.

Serious disinformation has been popularized and reflected in the guidelines given healthcare workers and the public encouraging the use of bleach (sodium hypochlorite) and other chlorinated products for cleaning the mold from damp indoor spaces. Biocides, including chlorine bleach, are harmful to humans and pets. Bleach is a strong corrosive material and will irritate the eyes, skin and respiratory tract. It is cytotoxic and genotoxic and has an accumulative effect on the body and can cause damage to organs.

In regard to using bleach on mold, at least two species of concern—Stachybotrys—propagate via spores that are unaffected by chlorine, acids, caustics or ozone. In addition, chlorinating carbon-based organic toxins increases their toxicity by increasing their mutagenicity and their lipid solubility which allows these poisons to enter the skin and accumulate in lipid rich tissue such as fat deposits and the brain.

OSHA was the first U.S. government agency to remove the recommendation for using bleach on mold, and they acknowledge that biocides are toxic to animals and humans.

Eventually, the EPA followed suit and said:

Biocides are substances that can destroy living organisms. The use of a chemical or biocide that kills organisms such as mold (chlorine bleach, for example) is not recommended as a routine practice during mold cleanup.

In regard to remediation of HVAC systems and ducts, the NADCA says source removal is the best method for cleaning HVAC systems. For best results, the entire HVAC system should be cleaned, including coils, blowers, and other components of the system.

In regard to whether biocides should be used inside air ducts, the NADCA does not recommend the use of chemicals within ductwork unless there is a specific need. They state:

Air duct cleaning service providers may tell you that they need to apply a chemical biocide to the inside of your ducts to kill bacteria (germs) and fungi (mold), and prevent future biological growth. Some duct cleaning service providers may propose to introduce ozone to kill biological contaminants. Ozone is a highly reactive gas that is regulated in the outside air as a lung irritant. However, there remains considerable controversy over the necessity and wisdom of introducing chemical biocides or ozone into the duct work.

What about the claims of some service providers that they need to use chemicals to “sanitize” the ductwork? According to the NADCA, using biocides to sanitize ductwork is illegal. They state:

The EPA has not registered any products for sanitizing or disinfecting ductwork. Further, no fungicides are registered for use in ductwork. It is a violation of federal law to use a product in a manner inconsistent with its labeling. For antimicrobials, this law is the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Therefore, any claims of sanitizing or disinfecting ductwork would require the use of a product in a manner inconsistent with its labeling, which is a violation of FIFRA. Violations of FIFRA can result in fines and criminal penalties from the EPA.

Another important note about remediation is the myth that you need to “kill the mold.” Although many products can easily kill mold, dead mold (if not removed) can be as dangerous as growing mold---due to the continued presence of highly toxic mycotoxins and viable spores which are often impervious to the effects of the agents used to kill the molds.

As the U.S. EPA says:

The purpose of mold remediation is to remove the mold to prevent human exposure and damage to building materials and furnishings. It is necessary to clean up mold contamination, not just to kill the mold. Dead mold is still allergenic, and some dead molds are potentially toxic.

Biocides are toxic to humans. Do not use fungicides developed for use outdoors for mold remediation or for any other indoor situation.

If someone tells you they have a product that can kill mold or “cure” a mold problem in your home, ask for their peer-reviewed, published research paper that validates the safety and efficacy of their product. To date, none of them have been able to provide such proof.