I recently met with Peter Moonen from MoldPro in Calgary. He graciously spent an hour with me answering my barrage of questions.
Molds are ubiquitous in nature, and mold spores are a common component of household and workplace dust. However, when spores are present in large quantities, they are a health hazard to humans, potentially causing allergic reactions and respiratory problems.
Some molds also produce mycotoxins that can pose serious health risks to humans and animals. The term "toxic mold" refers to molds that produce mycotoxins, such as Stachybotrys chartarum. Exposure to high levels of mycotoxins can lead to neurological problems and in some cases death.
Causes & growing conditions
Molds are found everywhere inside and outside, and can grow on almost any substance when moisture is present. Molds reproduce by spores, which can be carried by air currents. When these spores land on a moist surface that is suitable for life, they begin to grow. Mold is normally found indoors at levels that do not affect most healthy individuals.
Because common building materials are capable of sustaining mold growth, and mold spores are ubiquitous, mold growth in an indoor environment is typically related to water or moisture indoors. Mold growth may also be caused by incomplete drying of flooring materials such as concrete. Flooding, leaky roofs, building maintenance problems, or indoor plumbing problems can lead to mold growth inside homes, schools, or office buildings.
For significant mold growth to occur, there must be a source of water (which could be invisible humidity), a source of food, and a substrate capable of sustaining growth. Common building materials, such as wood, plywood, drywall, carpets are food for molds. In carpet, invisible dust and cellulose are the food sources (see also dust mites). After a single incident of water damage occurs in a building, molds grow inside walls and then become dormant until a subsequent incident of high humidity; this illustrates how mold can appear to be a sudden problem, long after a previous flood or water incident that did not produce such a problem inside apartment buildings, warehouses, retail shops, or office buildings.
Spores need three things to grow into mold:
-Nutrients: Cellulose is a common food for spores in an indoor environment.
-Moisture: Moisture is required to begin the decaying process caused by the mold.
-Time: Mold growth begins between 24 hours and 10 days from the provision of the growing conditions.
Mold colonies can grow inside building structures. The main problem with the presence of mold in buildings is the inhalation of mycotoxins. Molds may produce an identifiable smell. Growth is fostered by moisture. After a flood or major leak, mycotoxin levels are higher in the building even after it has dried out.
If a property has mold, the moisture may be from a leaking roof, or a leak in plumbing pipes behind the walls. Insufficient ventilation can further enable moisture build-up. Visible mold colonies may form where ventilation is poorest, and on perimeter walls, because they are coolest, thus closest to the dew point.
If there are mold problems in a property only during certain times of the year, then it is probably either too air-tight, or too drafty. Mold problems occur in airtight buildings more frequently in the warmer months (when humidity reaches high levels inside the house, and moisture is trapped), and occur in drafty properties more frequently
in the colder months (when warm air escapes from the living area into unconditioned space, and condenses). If a house is artificially humidified during the winter, this can create conditions favorable to mold.
Moving air may prevent mold from growing since it has the same desiccating effect as lowering humidity. Keeping indoor air temperature higher than 74 °F (23 °C) also has an inhibiting effect on mold growth.
Removing one of the three requirements for mold reduces or eliminates the new growth of mold. These three requirements are 1) Moisture, 2) Food source for the mold spores (dust, dander, etc), and 3) Warmth (mold generally does not grow in cold environments).
Commercial HVAC (Heating Ventilation & Air Conditioning) systems can create all three requirements for significant mold growth. The A/C system creates a difference in temperature that allows/causes condensation to occur. The high rate of dusty air movement through an HVAC system may create ample sources of food sources for the mold. And finally, since the A/C system is not always running - the ability for warm conditions to exist on a regular basis allows for the final component for active mold growth. This is why it is recommended to replace your air conditioning filters and consider duct cleaning regularly.
Because the HVAC system circulates air contaminated with mold spores and sometimes toxins, it is vital to prevent mold growth in the HVAC system.
The basic goals of any mold investigation are always twofold: 1) find the locations of mold growth, and 2) determine the sources of the moisture. If these can be answered by simpler or more cost-effective methods, mold testing is probably not a wise use of resources.
If mold is actively growing and is visibly confirmed, sampling for specific species of mold is unnecessary. Peter gave me a swab test kit ($45 each) that allowed me to test an area and have a result showing whether the mold is toxic to humans or not. You will get the result in exactly 10 minutes.
Sampling the air
In general the EPA does not recommend sampling unless an occupant of the space is symptomatic. When sampling is necessary it should be performed by a trained professional who has specific experience in designing mold-sampling protocols, sampling methods, and the interpretation of findings. Sampling should only be conducted to answer a pertinent question: examples "what is the spore concentration in the air", or "is a particular species of fungi present in the building." Sampling of the inside and outdoor air is conducted and the results to the level of mold spores inside the premises and outside are compared. Often, air sampling will provide positive
identification of the existence of non-visible mold.
The first step in solving an indoor mold problem is stopping the source of moisture. Next is to remove the mold growth. Common remedies for small occurrences of mold include:
Non-porous building materials
Significant mold growth may require professional mold remediation and removal of affected building materials. A conservative strategy is to discard any building materials saturated by the water intrusion or having visible mold growth.
Certain contractors are capable of repairing mold damage - usually by removing the affected areas and eliminating the cause of the excess moisture.
There are also cleaning companies that specialize in fabric restoration - a process by which mold and mold spores are removed from clothing to eliminate odor and prevent further mold growth and damage to the garments.
New technology also allows some mold remediation companies to fill a room with a dry fog that kills the mold and stops its growth. This fog uses a chemical that is EPA approved and does not harm or damage the physical well being of persons or animals.
Improper methods for cleaning mold include exposure to high heat, dry air, sunlight (particularly UV light), ozone, and application of fungicides. These methods may render the mold non-viable, however, the mold and its by-products can still elicit negative health effects. As noted in following sections, the only proper way to clean mold is to use detergent solutions that physically remove mold. Many commercially available detergents marketed for mold clean-up also include an anti-fungal agent. The most effective way at this point is formal Mold Remediation.
The goal of remediation is to remove or clean contaminated materials in a way that prevents the emission of fungi and dust contaminated with fungi from leaving a work area and entering an occupied or non-abatement area, while protecting the health of workers performing the abatement.
The purpose of the clean-up process is to eliminate the mold and fungal growth and to remove contaminated materials. As a general rule, simply killing the mold with a biocide is not enough. The mold must be removed since the chemicals and proteins, which cause a reaction in humans, are still present even in dead mold.
Wet vacuum cleaners are designed to remove water from floors, carpets and other hard surfaces where water has accumulated. Wet vacuuming should only be used on wet materials, as spores may be exhausted into the indoor environment if insufficient liquid is present. After use this equipment must be thoroughly cleaned and dried as spores can adhere to the inner surfaces of the tank, hoses, and other attachments.
Damp wipe is the removal of mold from non-porous surfaces by wiping or scrubbing with water and a detergent. Care must be exercised to make sure the material is allowed to quickly dry to discourage any further mold growth. With surfaces such as metal, glass, hardwood, plastics, and concrete, mold should be scraped off as much as possible. Then, scrub the surface with a moldicide or fungicide cleaner.
High Efficiency Particulate Air filtered vacuum cleaners are used in the final cleanup of remediation areas after materials have been thoroughly dried and all contaminated materials have been removed. HEPA vacuum cleaners are recommended for the cleanup of the outside areas surrounding the remediation area. During this process the workers wear proper personal protective equipment (PPE) to prevent exposure to mold and other contaminants. The collected debris and dust should be stored in impervious bags or containers in a manner to
prevent any release of debris.
During the remediation process, the level of contamination dictates the level of protection for the remediation workers. The levels of contamination are described as Levels I, II, and III. Each has specific requirements for worker safety. The levels are as follows:
Small Isolated Areas (10 sq. ft or less) for example, ceiling tiles, small areas on walls.
Remediation can be conducted by the regular building staff as long as they are trained on proper clean-up methods, personal protection (respirator, gloves, eye protection, etc), and potential hazards.
Mid-sized Isolated Areas (10-30 sq ft) – for example, individual wallboard panels.
Remediation can be conducted by the regular building staff as long as they are trained as for Level I. Respiratory protection, occupation of the work and adjacent areas, and handling of contaminated materials are the same as for Level I.
Surfaces in the work area that could become contaminated should be covered with sheet(s) of plastic that are secured in place. This should be done prior to any remediation process to prevent further contamination.
Dust suppression methods, such as misting (not soaking) surface prior to remediation, are recommended.
The work area/areas used by workers for access/egress should be HEPA vacuumed and cleaned with a damp cloth or mop and a detergent.
As with Level I, all areas should be left dry and visibly free of contamination and debris.
Large Isolated Areas (30-100 sq ft) – e.g., several wallboard panels
Industrial hygienists or other environmental health and safety professionals with experience performing microbial investigations and/or mold remediation should be consulted prior to remediation activities to provide oversight for the project.
It is recommended that personnel be trained in the handling of hazardous materials and equipped with respiratory protection (N-95 disposable respirator). Respirators must be used in accordance with OSHA respiratory protection standard (29 CFR 1910.134) Gloves and eye protection should also be worn.
Surfaces in the work area and areas directly adjacent that could become contaminated should be covered with a secured plastics sheet(s) before remediation to contain dust/debris and prevent further contamination.
Seal ventilation ducts/grills in the work area and areas directly adjacent with plastic sheeting.
The work area and areas directly adjacent should be unoccupied. Removing people from spaces adjacent to the work area is not necessary, but is recommended for infants (less than 12 month old), persons recovering from recent surgery, immune-suppressed or people with respiratory diseases.
Dust suppression methods, such as misting (not soakings) surface prior to remediation, are recommended.
Contaminated materials that cannot be cleaned should be removed from the building in sealed impermeable plastic bags and disposed of as ordinary waste.
The work area/areas used by workers for access/egress should be HEPA vacuumed and cleaned with a damp cloth or mop and a detergent.
All areas should be left dry and visibly free from contamination and debris.
In conclusion, after the moisture source has been eliminated and the mold growth removed, the premises should be revisited and then
re-evaluated to ensure the mold growth and the remediation process was
successful. The premises should be free of any moldy smells or visible
Source: Peter, MoldPro