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Toxic Mold & Remediation
Glossary of Terms

AEROSOL: small liquid or sold particle, which can remain suspended in air for some time.

ALLERGEN: a substance (such as a mold spore) that can elicit an excessive immune response such as hay fever, rashes, sinusitis, or asthma symptoms.

AMPLIFIER: An item (material, substrate, etc.) that supports the active growth and proliferation (increase in numbers) of mold.

ANTIMICROBIAL: an agent used to suppress or retard microorganisms on direct contact (e.g., a fungistatic agent is used against fungi).

BIOAEROSOL: Airborne particles or matter of biological origin (derived from a live or formerly living organism). For example, mold spores or fragments of a mold growth that are suspended in the air.

CLEANING: The science and practice of controlling contaminants by locating, identifying, containing, removing and disposing of unwanted substances from the environment.

COLONY: A uniform mass of cells all derived from a single cell and which is growing on a solid surface. A colony is usually the smallest unit of mold that can be observed with the naked eye.

CONTAINMENT: Barriers, seals, air-locks, negative air filtration systems and other methods used to control the movement of airborne materials or agents and avoid secondary contamination. For example, plastic sheeting used to enclose a work area to prevent disturbed mold particles from drifting from the containment zone into adjacent or connected areas.

CONTAINMENT BARRIER: polyethylene sheeting (or other nonpermeable materials) used to completely seal off work area to prevent the airborne distribution of contaminants to areas outside the containment zone.

DETERGENT: A cleaning agent. Detergency refers to the ability to remove soil.

DISINFECTANT: Any agent that significantly reduces the numbers of undesirable or infectious microorganisms, but may not eliminate all (e.g., not all bacteria or fungi spores).

DISINFECTION: The elimination and destruction of microorganisms, which may allow for survival of some resistant organisms (e.g., bacterial endospores or fungal spores).

ENCLOSURE: The practice of attaching a rigid and durable barrier to building components, with all edges sealed for the purpose of permanently enclosing contaminants.

EQUILIBRIUM RELATIVE HUMIDITY (ERH): The aw of a material expressed as a percentage where aw = equilibrium relative humidity/100. This can be estimated in the field by a relative humidity measurement at a material's surface using a hygrometer.

FUNGI: A biological kingdom of organisms that includes among many others, mushrooms, puffballs, yeasts, and molds. There are between 1000,000 and 10 million species of fungi.

FUNGISTATIC: A chemical agent incorporated into or applied onto a material to suppress or slow the growth of fungi on direct contact.

GENUS: A biological level of classification directly above the species level. In the practice of naming mold, the genus is indicated first and is capitalized (e.g., Aspergillus is the genus of the mold named, Aspergillus fumigatus). There often are many different species within a single genus. The plural form is genera.

HEPA: High efficiency particulate air. Capable of removal and capture of 99.97 % of dispersed particles greater than or equal to 0.3 microns in size. See the Dept. of Energy standard DOESTD-3020-97 for details.

HEPA-FILTERED VACUUM: A high-efficiency particulate air filtered vacuum with a properly installed filter capable of collecting and retaining particulate matter 0.3 microns or larger at an efficiency rate of 99.97%.

HIDDEN MOLD: Mold growth on building materials or assemblies of building components that are obscured from the view of an observer within building spaces normally intended for occupancy. Common examples include contamination beneath carpeting or padding, behind fixed cabinetry or shelving units, in spaces above a drop ceiling, in air handling or distribution systems, or within a wall cavity.

HYPERSENSITIVITY PNEUMONITIS: (aka extrinsic allergic alveolitis). A syndrome characterized by inflammation of the lungs, caused by inhalation of certain allergens. Typically occurs in the occupational setting following the repeated inhalation of very high levels of an allergen(s), including mold allergens (e.g., farmer's lung).

LASER PARTICLE COUNTER: Electronic device that scans the air for particles in different size ranges. For mold spores, the channels of 5 micron and 10 micron are used. In this particle size range dust can interfere with the measurements, however generally speaking dust is evenly spread throughout a buildings and if you scan using the laser counter from room to room when you see particles in the 5 and 10 micron range jump, most likely there is a mold problem in that room.

METABOLITE: A chemical produced by the metabolism of a living organism; produced by enzymatic action.

MICROBE: a microorganism, including types of fungi and bacteria that are usually not visible to the naked eye. Indoor biological contamination can include other microbes in addition to mold, and this may affect the remediation strategy.

MICRON: A unit of measure equal to one millionth (10-6) of a meter; also known as a micrometer. Approximately equal to 1/25,000 inch.

MOISTURE CONTENT: The mass of moisture held in a material, relative to the material. Measured as the mass of water as a percentage of the dry mass of a material. Expressed as a percentage [(wet mass – dry mass) (100)]/(dry mass), or in terms of mass of water over material volume. Moisture content can be measured in the field using a moisture meter that is appropriate and calibrated for the material. Different moisture content values can be tolerated, depending on the material, before mold growth occurs.

MVOCs: Microbial Volatile Organic Compounds: chemicals that can be produced by actively growing molds and bacteria, which are released as gases into the air and are responsible for the characteristic moldy or musty odor .

MYCOTOXIN: A harmful substance produced by a fungus, which affects the structural or functional integrity of cells or tissues. Mycotoxins are usually found in the spores, filamentous structures, and/or the surrounding growth material.

MYCOLOGIST: A microbiologist who studies or has "expert" knowledge of fungi.

NADCA: National Air Duct Cleaners Association. Trade group that publishes the standard Assessment, Cleaning, and Restoration of HVAC Systems (ACR-2002).

NEGATIVE PRESSURE: An atmosphere created in an enclosure such that the air pressure within the enclosure is less that that outside the enclosure resulting in the tendency for airborne particles to be drawn in rather than out.

NIOSH: National Institute for Occupational Safety and Health

ODTS: Organic Dust Toxic Syndrome (same disease as humidifier fever; also referred to as silo unloader's disease and pulmonary mycotoxicosis). Illness characterized by chest tightness, flulike symptoms, and possibly other symptoms following a single very heavy microbial exposure (including mold). Such extreme conditions are rarely found in homes or offices.

PATHOGENIC: A microbe capable of causing disease by direct contact, typically through infection. The molds most often regarded as pathogenic are those most frequently known to cause opportunistic fungal infections, primarily among immune-compromised individuals (e.g., Aspergillus fumigatus). A microbe that produces toxins that cause disease in the absence of the microbe is not defined as pathogenic.

POROUS: Strictly defined, porous refers to the ability of a material to allow fluids to pass through (permeability to liquids or gases). For the purposes of this document, porous materials are items that absorb moisture (liquid water or humidity). Examples include wood products, paper products, fabric, carpet and pad, plasterboard, drywall, insulation, and ceiling tiles. In contrast, non-porous materials include Formica, vinyl, plastic, glass, some tile, metal and many other similar hard surfaced durable or sealed materials.

PROPAGULE: Particles that are capable of germinating and producing a colony (for example, mold spores or fragments of hyphae).

PROTECTIVE CLOTHING: garments worn by workers to keep gross contamination from contacting skin surfaces and reaching underlying clothing layers.

RELATIVE HUMIDITY (RH): A ratio quantifying the actual amount of water present in air to the maximum amount of water that air (at the same temperature) is capable of holding; this ratio is expressed as a percentage. Warmer air has a greater capacity to hold water in the vapor form than does cooler air.

REMEDIATION: The spectrum of measures intended to correct a problem and restore the environment to a useable state. Mold remediation as any combination of activities which: a) remove indoor mold growth and mold contaminated materials, b) eliminate and prevent excess moisture that allows growth, and c) rebuild or refurnish.

SANITIZER: An agent with cleansing and antimicrobial properties that reduces or inhibits microbial growth.

SPECIES: The next most specific level of biological classification below genus. In the practice of naming mold, the species follows the genus and its first letter is always written in the lower case (e.g., fumigatus, in Aspergillus fumigatus).

SPORE: A specialized reproductive cell. Mold spores are individually microscopic and many are very buoyant. As such, they readily stay suspended in the air and can be dispersed by air movement. Some spores of mold and bacteria may be highly resistant and able to survive adverse environmental conditions.

STERILIZE: Kill or inactivate all microorganisms.

STERILANT: An agent or process used to sterilize a surface or media.

TAXONOMY: An orderly system for classifying and naming living organisms based upon how closely groups or individuals are related. See also GENUS and SPECIES.

TOXIC: Toxic refers to the inherent ability of a substance to cause harm to living cells or biological tissues.

TOXIGENIC: An organism that can produce one or more toxins. Examples of fungi that can produce toxins under certain conditions include the certain species of Aspergillus, Penicillium, Fusarium, Trichoderma, Memnoneniella, and Stachybotrys chartarum (note other species may also produce toxins).

VIABLE: Able to reproduce under appropriate conditions (the opposite of non-viable). Some mold testing methods only detect molds that will grow on the specific culture medium used– molds that are non-viable or don't grow on that medium will be missed. Some mold spores can remain viable for many years.

WATER ACTIVITY (aw): A physical-chemical concept that describes the moisture in a solid material and can be used to express the availability of free moisture for the growth of microorganisms. It is expressed as a decimal fraction less than or equal to 1; where a material's water activity is 1.0 when it is saturated. There is no direct field technique to measure water activity and it can only be related to moisture content for a specific material (see EQUILIBRIUM RELATIVE HUMIDITY).

Dr. Rosen's full book can be found on his website listed below.

Gary Rosen, Ph.D.
Certified Mold Free, Corp.
954 614-7100 tel
954 452-3543 fax


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