Introduction to Mold Remediation and Toxic Mold

Introduction to Mold Remediation and Toxic Mold

Introduction to Mold Remediation and Toxic Mold

Molds gradually destroy anything they grow on. The key to controlling mold is to control moisture. By eliminating mold growth, it is possible to:

  • Prevent damage to materials and furnishings
  • Save money
  • Eliminate health risks

Concern about indoor exposure to mold increases as people come to learn that mold exposure can cause a variety of health problems including allergic reactions. This blog presents some guidelines for mold remediation and moisture control in commercial buildings. The guidelines include measures that focus on protecting the health of building occupants. The guidelines are intended for building maintenance personnel.


This blog can serve as a reference for mold remediators as well as individuals with little or no experience with mold remediation. It is possible to use the guidelines presented in this blog to evaluate a remediation plan submitted by 3rd party contractors.


Molds are Found Everywhere

They can grow on any organic substance if moisture and oxygen are present. Molds can grow on wood, paper, carpets, foods most other materials. When excessive moisture accumulates in buildings or on building materials, mold growth will often occur, particularly if the moisture problem remains undiscovered or unaddressed. Eliminating all mold and spores from an indoor environment is impossible. Mold growth can be controlled indoors by controlling moisture.


Molds reproduce by spawning spores that typically cannot be seen by the naked eye. Mold spores continue growing and spreading continuously. When mold spores land on moist spots, they begin growing and digesting whatever they are growing on in order to survive. Molds gradually destroy the things they grow on.


Photo 1: Extensive mold contamination.


Common Types of Toxic Mold

  1. Stachybotrys.Stachybotrys is also known as black mold. It is one of the more harmful toxic mold species. Black mold is usually found in houses. This species can cause lungs to bleed, which is fatal to animals and infants. Black mold is hard to detect; it usually develops behind walls and under ceilings and is resistant to regular air sampling.
  2.  MemnoniellaMemnoniella, also referred to as black mold. It is like #1 above and has the same effects. Memonielladiffers insofar as when viewed under a microscope, its spores are released in chains, whereas the spores of Stachybotrys are released in clumps.
  3. AspergillusAspergillusappears on wood surfaces. Aspergillus, with 20 species in total, is dangerous because it will often cause allergies, leading to serious asthmatic reactions, hay fever or lung infections. Every Aspergillus species produces toxins, which are a health hazard, especially for those individuals with compromised immune systems.
  4. Penicillum. There are many species of Penicillum– some beneficial and some not. Penicillum can be used to produce cheese and medicine. Like other molds, Penicillium causes allergies. It is especially troublesome for people that have weak immune systems.
  5. AlternariaAlternariais one of the most prevalent toxic molds and includes many species. Asthma and hay fever are among conditions that are affected. Inhaling Alternaria spores can be dangerous.
  6. Geotrichum.Geotrichum is white and usually appears powdery. It is known to spread quickly. It is frequently associated with adverse health conditions such as tuberculosis and other pulmonary infections. It is an allergen that causes itchy eyes, fatigue, and sometimes chronic headaches.
  7. Trichoderma.Trichoderma is also white and has green patches. It thrives in moist areas. It has five subspecies, most of which are non-pathogenic. However, some of the subspecies have been associated with liver and pulmonary infections. Trichoderma contains a lethal enzyme, which can destroy materials such as wood, textiles and paper. This may lead to buildings crumbling when the materials rot.
  8. Chaetomium.Chaetomium is also allergic. It is often found in drywall that has previously been damaged by water. Its spores have been linked to autoimmune diseases, neurological damage and allergic reactions such as difficulty in breathing and red, watery eyes. It has a musty odor and flourishes in wet, dark environments such as under carpets, drywall, baseboards, and wallpaper. Chaetomium is often mistaken for black mold as they have the same characteristics and exists in similar environments.
  9. Bipolaris.As it begins to grow, bipolaris is whitish or grayish brown, but gradually turns to dark olive. It looks soft and fluffy and usually grows outdoors on grasses and soil. It also thrives in water damaged materials such as carpets, hardwood floors, and houseplants. Bipolaris grows rapidly and takes only about five days to mature. It is a well-known allergen and may cause asthma, wheezing, stuffy nose and coughing when inhaled.
  10. Ulocladium.Ulocladium is black and often found in wet areas and homes that have suffered water damage. It commonly grows in bathrooms, basements, and kitchens. Ulocladium has two subspecies. Both of them are highly allergic. It is linked to severe allergic reactions such as hay fever and sometimes skin infections. Prolonged exposure to its spores causes difficulty in breathing and asthma-like symptoms.
  11. Fusarium.Fusariumcan range from pink, reddish or white in color. It can adapt to colder temperatures and mostly grows on food products, compost, carpets, wallpaper, and any other water-damaged materials. Exposure can cause allergic reactions, including sore throat, dermatitis, itchy eyes and runny nose. Further exposure can cause lethal conditions such as brain abscess and bone infections. Its toxins can damage the nervous system and cause internal bleeding.
  12. Aureobasidium.Aureobasidium is also allergic and may cause skin, eye and nail infections. It is normally pink, brown or black, but gradually turns to dark brown as it matures. This mold grows in wet and water-damaged areas as such behind wallpapers, wooden surfaces, and carpets.
  13. Cladosporium.Cladosporium can survive in both cold and warm environments. It commonly grows indoor in carpets, fabrics and under floorboards. It is brown in or sometimes olive-green with a suede-like texture. Exposure to its spores can cause a variety of allergic reactions, including itchy eyes, runny nose, sore throat, and skin infections. It is also associated with asthma, sinusitis and lung infections.
  14. Ascospores.Ascospores thrive in damp substrates and other water damaged indoor areas. It is one of the most resistant types of mold. Even after drying a wet surface, it may continue surviving until it finds another conducive environment for growth. It is commonly found in labs where it is spread by infected animals. Ascospores come in different groups such as Dermatophytes, which can destroy keratin-based materials such as nails and hair and the Histoplasmacapsulatum, which is specifically resistant to dry conditions.
  15. Basidiospores.Basidiospores are typically spread by wind and released when there is humidity or rain. It mostly grows outdoors in woodlands, gardens, forests and indoors on damp environments. Basidiospores are also allergens and may cause such reactions as asthma, hay fever, and Lycoperdonosis, and can be identified by air sampling.


All molds have the potential to cause health effects. Molds can produce allergens that can trigger allergic reactions or asthma attacks in people allergic to mold. Others are known to produce potent toxins and/or irritants. Potential health concerns are an important reason to prevent mold growth and to remediate/clean up any existing indoor mold growth.

Since mold requires water to grow, it is important to prevent moisture problems. Moisture problems have many causes, including uncontrolled humidity. Some moisture problems in buildings have been linked to changes in building construction practices during the 1970s, 1980s and 1990s. Some changes have resulted in buildings that are tightly sealed, but lack adequate ventilation, potentially leading to moisture buildup. Building materials, such as drywall, may not allow moisture to escape easily. Moisture problems may include:

  • Roof leaks
  • Landscaping or gutters that do not direct water away from the foundation.
  • Unvented combustion appliances
  • Delayed or insufficient maintenance

Moisture problems in various structures have frequently been associated with mold problems.

When mold growth occurs, adverse health problems may be reported by some occupants, particularly those with allergies or respiratory problems. Remediators should avoid exposing themselves and others to mold-laden dusts as they conduct their cleanup activities. Caution should be used to prevent mold and mold spores from being dispersed throughout the air where they can be inhaled by building occupants.


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