Reference · 56 Terms
Mold & Indoor Air Quality Glossary
Plain-English definitions for the mold testing, sampling, and lab-reporting terms you'll see on inspection reports and in real estate transactions. Maintained by Spore Shield — a certified, independent, third-party mold testing company based in West Bloomfield, MI and serving Oakland County and Southeast Michigan. This is an educational reference and is not medical advice.
A
- AIHA
- American Industrial Hygiene Association — the professional body whose laboratory accreditation program (AIHA-LAP) sets quality standards for environmental mold and air-sample analysis. A 'certified third-party AIHA/NVLAP-accredited lab' means the lab has met those standards independently of the inspector.
- Air-O-Cell cassette
- A common, single-use spore-trap cassette used during indoor air sampling. Air is drawn through the cassette at a calibrated flow rate, capturing airborne spores and particulates on a sticky slide for laboratory microscopy.
- Air sampling
- The collection of indoor (and a paired outdoor 'control') air over a measured time period to quantify mold spores per cubic meter of air. Air sampling is the most common way to evaluate hidden mold and indoor air quality.
- Alternaria
- A common outdoor mold genus frequently found indoors near windows, in showers, and on damp surfaces. Often used as a benchmark of typical indoor/outdoor exposure.
- Ascospores
- Sexually produced spores from a wide range of fungi (the Ascomycota). On a spore-trap report, 'ascospores' is usually a category total rather than a single species.
- Aspergillus
- A very common airborne mold genus. Spore-trap analysis often cannot distinguish Aspergillus from Penicillium under the microscope, so the two are reported together as 'Pen/Asp.'
B
- Background sample (outdoor control)
- An air sample collected outdoors at the time of an indoor inspection. The outdoor result is the baseline against which indoor genera and spore counts are compared — a key reason a single 'indoor' number alone cannot be interpreted.
- Basidiospores
- Spores produced by mushroom-forming fungi (Basidiomycota), including many wood-decay fungi. Elevated indoor basidiospore counts can point to chronic wood moisture or active wood-rot activity.
- Bulk sample
- A physical piece of a suspect material (drywall, insulation, carpet, etc.) collected and sent to the lab for direct microscopic and/or culture analysis.
C
- Certified Mold Inspector (CMI)
- A professional certification indicating an inspector has completed formal training in mold inspection methodology, sampling procedures, and reporting. Specific issuing bodies and curricula vary; the credential is one of several markers buyers, lenders, and attorneys may look for.
- Chaetomium
- A mold genus strongly associated with water-damaged cellulose materials such as drywall paper, cardboard, and damp wood. Its presence indoors generally indicates a sustained moisture event.
- Cladosporium
- One of the most common indoor and outdoor molds worldwide. Often used as a baseline genus when comparing indoor air-sample results to the outdoor control.
- Class of water damage (1–4)
- An IICRC S500 water-damage classification (Class 1 through Class 4) describing how much water a building has absorbed and how quickly it must be dried. Higher classes mean wetter materials, longer dry times, and higher downstream mold risk.
- Colony forming unit (CFU)
- The unit used in viable (culture-based) mold sampling. A CFU represents one viable spore or hyphal fragment capable of growing into a colony on lab media — distinct from the total-spore counts produced by spore-trap analysis.
- Condition 1
- An IICRC S520 environmental designation meaning a normal indoor fungal ecology — no abnormal mold growth, no settled spores from a contaminated source. The post-remediation goal for most projects.
- Condition 2
- An IICRC S520 designation meaning indoor surfaces are settled with spores or fragments from a Condition 3 area, but no active fungal growth is present in the Condition 2 area itself.
- Condition 3
- An IICRC S520 designation meaning actual indoor mold growth is present — visible colonies, hidden growth, or growth on materials. Condition 3 areas typically require remediation.
- Conflict of interest (testing + remediation)
- A structural bias that occurs when the same company both performs mold testing and sells the remediation work. Findings can favor the company's own remediation revenue. Independent, testing-only providers exist specifically to remove this bias.
D
- Dew point
- The temperature at which water vapor in the air condenses into liquid. When indoor surfaces (windows, exterior walls, cold-water pipes) drop below the room's dew point, condensation forms — a frequent feeder of hidden mold.
E
- ERMI
- Environmental Relative Moldiness Index — a dust-based, DNA (qPCR) test that scores a settled-dust sample against a panel of 36 mold species. ERMI is a research-derived index, not a clearance test.
F
- FLIR
- A widely used brand of forward-looking infrared (thermal) cameras. In a mold inspection, FLIR imaging is used to identify temperature anomalies — typically cold, wet spots — that may indicate hidden moisture behind finished surfaces.
H
- HEPA filtration
- High-Efficiency Particulate Air filtration capable of capturing at least 99.97% of particles 0.3 microns in size. Used in air scrubbers, vacuums, and respirators during remediation work.
- HERTSMI-2
- Health Effects Roster of Type-Specific Formers of Mycotoxins and Inflammagens, version 2 — a five-species subset of ERMI used as a simpler scoring tool. Like ERMI, it is a screening index and not a clearance standard.
- Hygrometer
- An instrument that measures the relative humidity of air. Used during inspections to document indoor RH and identify rooms operating above the 60% threshold where mold growth becomes more likely.
- Hyphae
- The branching, thread-like filaments that make up the body of a mold colony. A mass of interconnected hyphae is called mycelium. Hyphal fragments are visible on tape-lift and bulk samples and can indicate active growth rather than mere settled spores.
- HVAC
- Heating, Ventilation, and Air Conditioning. HVAC systems can move spores throughout a structure, create condensation in poorly insulated ducts, and concentrate biological growth on coils and drip pans.
I
- IICRC S520
- The Institute of Inspection, Cleaning and Restoration Certification's professional standard for mold remediation. It defines the Condition 1/2/3 classifications and the procedures expected of qualified remediation contractors.
- Indoor air quality (IAQ)
- A general term for the chemical, biological, and particulate characteristics of indoor air. Mold testing is one component of a broader IAQ assessment.
- Infrared (IR) imaging
- The use of a thermal camera (such as FLIR) to visualize surface-temperature differences. In mold inspection, IR imaging helps locate hidden moisture without invasive demolition.
L
- Laboratory (third-party)
- An independent analytical lab — separate from the inspector and the property owner — that processes mold samples. Spore Shield uses a certified third-party AIHA/NVLAP-accredited lab so results are not produced by the same party that collected them.
M
- Microbial volatile organic compounds (mVOCs)
- Volatile compounds produced by actively growing mold and bacteria — the source of the characteristic 'musty' or 'earthy' odor associated with hidden mold. mVOC odor can suggest active growth even when no visible colony has been found.
- Moisture meter
- A handheld instrument that measures the moisture content of materials such as drywall, wood framing, and subfloor. Pin-type and pinless versions are both used during inspection to locate active wetting.
- Mold
- A diverse group of multicellular fungi that grow as hyphae and reproduce via spores. Mold needs an organic food source plus moisture to grow indoors.
- Mold inspection vs. mold testing
- Inspection is the on-site, visual and instrumented assessment (walkthrough, moisture meter, thermal imaging). Testing is the collection and lab analysis of physical samples (air, swab, tape, bulk). Most projects combine the two — inspection guides where, and how many, samples are worth collecting.
- Mycelium
- The vegetative body of a mold colony — a mat of interconnected hyphae growing through or on a substrate. Visible mold patches on drywall, wood, or insulation are typically mycelium.
- Mycotoxin
- A secondary metabolite produced by certain molds under specific growth conditions. This entry defines what a mycotoxin is; it does not describe health effects, which are outside the scope of this glossary.
N
- NVLAP
- National Voluntary Laboratory Accreditation Program — a U.S. National Institute of Standards and Technology (NIST) program that accredits testing laboratories. NVLAP accreditation is a key independence and quality marker for environmental labs.
P
- Penicillium (Pen/Asp)
- A very common airborne mold genus. Because Penicillium and Aspergillus spores look nearly identical under the microscope, spore-trap reports usually combine them as a single 'Pen/Asp' count.
- Post-remediation clearance
- Independent verification — typically by a third-party tester who did not perform the remediation — that completed work has returned the affected area to a normal indoor fungal ecology (Condition 1). Frequently required for insurance claims.
R
- Relative humidity (RH)
- The amount of water vapor in the air expressed as a percentage of the maximum the air can hold at that temperature. Indoor RH above ~60% sustained over time substantially increases mold-growth risk.
- Remediation
- The process of removing and cleaning mold-contaminated materials and addressing the underlying moisture source. Spore Shield does not perform remediation — we provide independent testing only.
- Remediation protocol
- A written, scope-of-work document — typically prepared by an Indoor Environmental Professional — that specifies containment, removal, cleaning, and clearance criteria for a remediation contractor to follow.
S
- Spore
- The reproductive unit of mold. Spores are microscopic, can remain airborne, and are what a spore-trap air sample is designed to capture and count.
- Spore trap
- A general term for cassette-based air-sampling devices (such as Air-O-Cell) that physically capture airborne spores and particulates on an adhesive slide for laboratory microscopy.
- Spores per cubic meter (spores/m³)
- The standard unit for reporting airborne mold concentrations. It allows direct comparison between indoor samples and the paired outdoor control collected at the same time.
- Stachybotrys chartarum
- Commonly called 'black mold,' Stachybotrys chartarum is a slow-growing mold that requires sustained wetting of cellulose-based materials (drywall paper, cardboard, damp wood). Indoor detection generally indicates a chronic or significant water source.
- Surface sampling
- Collecting samples from a suspect surface, typically by swab, tape-lift, or bulk. Used to identify what is on a visible spot or stain, rather than what is airborne.
- Swab sample
- A sterile cotton or polyester swab rubbed across a suspect surface and submitted to the lab. Useful when the inspector needs to identify the genera present in a specific visible deposit.
T
- Tape lift sample
- A clear adhesive strip pressed against a suspect surface to lift spores, hyphae, and debris for direct microscopic analysis. Tape lifts preserve structure and are often more informative than swabs for visible growth.
- Thermal imaging
- The use of an infrared camera to visualize surface-temperature differences across walls, ceilings, and floors. In mold inspection it is a non-destructive way to locate likely moisture intrusion.
- Third-party testing
- Testing performed by a party with no financial interest in the outcome — specifically, one that does not also sell remediation. Third-party results are what lenders, insurers, and real estate attorneys typically require for documentation.
V
- Vapor barrier
- A sheet material (commonly polyethylene) installed to slow water-vapor diffusion through floors, walls, or crawl-space ground. Failed or missing vapor barriers are a frequent root cause of hidden moisture in slab and crawl-space homes.
- Viable vs non-viable sampling
- Non-viable sampling (spore-trap) counts all spores whether alive or dead. Viable sampling cultures live spores on growth media to identify species and confirm activity. Each method answers a different question.
- Visual mold inspection
- A focused on-site walkthrough using moisture meters and thermal imaging, without lab air sampling. Often the right first step when a homeowner has a specific concern they want a professional eye on before committing to full lab analysis.
W
- Water activity (aw)
- A measure of the moisture available in a material to support microbial growth, expressed from 0 to 1. Most molds require an aw above roughly 0.7; species like Stachybotrys require sustained values above ~0.9.
- Water-damaged material
- Any building material (drywall, insulation, framing, flooring, ceiling tile) that has been wetted long enough to support — or potentially support — fungal growth. Identifying and addressing the moisture source is a prerequisite to any meaningful remediation.
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