Mold Glossary

Key terms used in mold identification, testing, and remediation — explained without jargon.

Aflatoxin
Toxic compounds produced by certain Aspergillus molds. Found mainly on agricultural products; not common in household mold situations but a severe health risk at high exposure.
Airborne Mold Spores
Microscopic reproductive units that mold releases into the air. Spores are always present indoors and outdoors at low levels; elevated counts indicate active mold growth.
Aspergillus
A common genus of mold with hundreds of species. Found in soil, food, and decaying vegetation. Some species produce mycotoxins; others are relatively harmless. Often appears green, yellow, or black.
Black Mold
A colloquial term typically applied to Stachybotrys chartarum, a dark greenish-black mold associated with chronic water damage. "Black mold" is not a scientific classification — many molds appear black, not all are toxic.
Cladosporium
One of the most common indoor and outdoor molds. Appears olive-green to black. Typically found on textiles, wood, and HVAC systems. Less toxic than Stachybotrys but a major allergen.
Containment
In remediation, the practice of physically isolating the work area using polyethylene sheeting and negative air pressure to prevent spores from spreading to unaffected areas during cleanup.
ERMI
An EPA-developed DNA-based test that measures 36 mold species in settled dust to assess mold burden in a home. More precise than air sampling for baseline assessments.
HEPA
A filter standard that captures 99.97% of particles ≥0.3 microns — including mold spores. Required in professional remediation air scrubbers and vacuums.
HVAC Mold
Mold growth within heating, ventilation, and air conditioning systems. Dangerous because the system can distribute spores throughout the entire building. Requires professional cleaning.
IICRC S520
The industry standard for professional mold remediation published by the Institute of Inspection, Cleaning and Restoration Certification. Sets protocols for assessment, containment, and clearance.
Mold
A type of fungus that grows in multicellular filaments called hyphae. Reproduces via spores. Requires moisture, an organic food source, and suitable temperatures. Over 100,000 species exist.
Mold Assessment
A professional evaluation of a property for mold presence, typically including visual inspection, moisture measurement, and air or surface sampling. Performed by a certified industrial hygienist (CIH) or mold inspector.
Mold Remediation
The process of identifying, containing, and removing mold from a structure, followed by addressing the moisture source that caused growth. Distinct from simple mold cleaning.
Moisture Meter
A device used to measure moisture content in building materials. Essential for finding hidden water intrusion behind walls, under floors, and in ceilings — the leading cause of mold growth.
Mycotoxin
Toxic secondary metabolites produced by certain molds under specific conditions. Include aflatoxins (Aspergillus) and trichothecenes (Stachybotrys). Exposure can cause illness; require specialist remediation.
Negative Air Pressure
A containment technique where exhaust fans create slightly lower pressure inside the remediation zone than outside, causing air to flow inward rather than outward — preventing spore escape.
Penicillium
A common blue-green mold often found on food and water-damaged building materials. Some species produce mycotoxins; all are potent allergens. Frequently found alongside Aspergillus.
Post-Remediation Verification
Independent testing performed after remediation to confirm that mold levels have returned to acceptable ranges and no viable mold remains in previously affected areas.
Relative Humidity
The amount of moisture in the air as a percentage of the maximum it can hold at that temperature. Sustained indoor RH above 60% creates conditions favorable for mold growth.
Stachybotrys chartarum
Commonly called "black mold" or "toxic black mold." Requires very wet, cellulose-rich material (drywall, paper) to grow. Slow-growing; its presence indicates chronic moisture problems. Produces trichothecene mycotoxins.
Vapor Barrier
A material (typically polyethylene sheeting) installed in crawl spaces or on walls to prevent moisture vapor from migrating into the structure — reducing mold risk.
VOC
Volatile Organic Compounds — gases emitted from mold and other sources. Mold VOCs (mVOCs) produce musty odors and can cause respiratory irritation even without direct spore exposure.
Water Activity
A measure of the availability of water in a material for microbial growth. Mold can grow at water activity levels above 0.70; Stachybotrys requires levels above 0.90 (very wet conditions).

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