Mold Inspection and Lab Report Glossary

Plain-language definitions of terms in mold inspection reports and lab results, grouped by topic. For how the pieces fit together, see how to read a mold lab report and mold inspection reports explained.

Collecting samples

Air sample: A measured volume of air drawn through a collection device by a calibrated pump. The volume, usually in liters, is recorded because every concentration depends on it.
Spore trap: An air sample in which particles strike and stick to a small adhesive-coated slide inside a cassette, then are examined under a microscope. Also called a “total spore” or “non-viable” sample.
Air-O-Cell / cassette: Air-O-Cell is one brand of spore trap cassette that AIHA lists among commonly used designs.
Non-viable: AIHA uses this term for spore trap analysis, which counts spores by appearance whether or not they are alive or able to grow.
Culture (viable) sample: Particles collected onto a growth medium such as an agar plate and grown in the lab. Only organisms that grow on that medium are counted; AIHA notes results usually take seven to 14 days.
Outdoor control (baseline): An outdoor air sample collected the same day for comparison. EPA says that after remediation, indoor types and concentrations should be similar to local outdoor air.
Comparison area: A similar indoor area without complaints, sampled to compare.
Tape lift: Clear adhesive tape pressed on a surface, then mounted on a slide to show what is on that spot.
Swab: A sterile swab wiped over a defined spot on a surface and sent to the lab in a sealed tube.
Bulk sample: A piece of the material itself, such as drywall, carpet, or insulation, sent to the lab.
ERMI: Environmental Relative Moldiness Index, an EPA-developed research tool that uses a DNA-based (PCR) method to analyze mold in settled dust. EPA does not recommend it for routine public use. More on our testing methods page.

Reading lab results

Raw count: The number of spores of a given type the analyst actually counted.
Counts per cubic meter (spores/m³): The raw count converted to a concentration using the air volume and the portion of the slide read.
Analytical sensitivity: The concentration represented by a single counted spore in that sample. Smaller air volumes or partial reads make it larger.
Limit of detection / ND: The lowest amount a method can reliably report. “ND” (none detected) means nothing was seen in the portion examined, not a true zero. Labs use these terms differently; check the report’s key.
Hyphal fragments: Pieces of the thread-like filaments (hyphae) that make up a mold’s body, reported separately from spores.
Background debris: Non-fungal particles on the slide, often rated on a scale. ASTM D7391 requires reporting it because heavy debris can hide spores and bias counts.
Rare / few / moderate / many: Descriptive amounts for surface samples; scales vary by lab.
CFU: Colony-forming units, the unit for culture results (for example, CFU/m³). AIHA notes there is no reliable correlation between culture and spore trap results.
Semi-quantitative: AIHA’s description of spore trap results: useful for comparison, not a precise measurement. Airborne levels swing with time and room activity.
Spore: The microscopic reproductive unit of a mold, roughly 2 to 100 micrometers across per EPA.

Mold types you’ll see named

Mold (fungi): Organisms in the kingdom Fungi that grow on damp organic material and spread by spores. Moisture is the factor that limits indoor growth.
Cladosporium: Among the most commonly reported spore types in outdoor air and often present indoors; indoor levels well above outdoor levels are what draw attention.
Penicillium/Aspergillus: Two groups whose spores look alike under a microscope, so spore trap reports usually combine them.
Stachybotrys: A greenish-black mold that CDC says can grow on high-cellulose materials such as gypsum board and paper. See black mold.
Chaetomium: A mold frequently found on damp building materials in published studies of water-damaged buildings.
Water-indicator organisms: An informal label for molds, such as Stachybotrys and Chaetomium, associated with materials that stayed wet. A clue about moisture history, not a health finding.
“Black mold”: A popular term, not a scientific one. CDC says all molds should be treated the same regarding potential health risks and removal. Anyone with symptoms should talk with a physician.
Mycotoxins: Toxic substances some molds can produce. EPA notes little is known about the health effects of many of them.
mVOC: Microbial volatile organic compound, a chemical made by mold that can cause a musty odor.

Moisture and building terms

Relative humidity (RH): The moisture in the air as a percentage of what the air could hold at that temperature. EPA recommends keeping indoor RH below 60 percent, ideally 30 to 50. See indoor humidity.
Dew point: The temperature air must cool to for RH to reach 100 percent. Surfaces colder than the dew point collect condensation.
Condensation: Water that forms when warm, humid air meets a cold surface, such as an uninsulated duct. See HVAC condensation.
Moisture content / moisture meter: How much water a material holds. EPA notes moisture meters can check carpet, wallboard, wood, brick, and concrete.
Thermal imaging: An infrared camera shows surface temperature differences. Evaporating moisture can make a wet area look cooler, but the camera doesn’t measure moisture, so findings are confirmed with a meter.
Moisture source: What keeps materials wet; see moisture sources.

Cleanup and remediation

Remediation: Correcting the moisture problem and removing or cleaning mold-damaged materials. Vegas Mold Pro does not perform remediation. See choosing a remediation contractor.
Containment: Plastic sheeting barriers that keep mold and debris from spreading during removal. EPA describes limited containment for about 10 to 100 square feet and full containment for larger areas.
Negative air (negative pressure): Exhausting air from containment so air flows into the work area, not out.
HEPA: High-efficiency particulate air. EPA says a HEPA filter can theoretically remove at least 99.97 percent of airborne particles 0.3 microns in size.
PPE / N95: Personal protective equipment. EPA and CDC list an N95 respirator, gloves, and eye protection as a minimum when disturbing mold.
Biocide: A chemical that kills organisms such as mold. EPA says biocides such as bleach are not recommended as a routine remediation practice, and CDC warns never to mix bleach with ammonia.
Clearance testing (post-remediation verification): An inspection, sometimes with sampling, after remediation to check whether the work area is clean and dry. EPA notes post-remediation sampling can help show whether the work was effective.

Labs, standards, and quality

AIHA: The American Industrial Hygiene Association, a professional association for occupational and environmental health and safety.
AIHA EMLAP: AIHA’s Environmental Microbiology Laboratory Accreditation Program for labs analyzing air, surface, and bulk samples.
EMPAT: AIHA’s proficiency testing program. AIHA notes participation alone is not the same as EMLAP accreditation.
ISO/IEC 17025: The international standard for testing lab competence; AIHA strongly recommends labs accredited to it.
ASTM D7391: A published standard method for analyzing spore trap samples by microscopy.
Chain of custody: The signed record of who handled each sample and when, from collection to analysis.
Sampling variability: AIHA notes that a single sample can’t represent an area, which is why reports rely on patterns across samples and on the inspection itself.

Sources

Still have questions about your report?

Vegas Mold Pro does independent inspection and testing only. Samples go to an independent AIHA-accredited lab, and written reports typically arrive within 24 hours. Call (702) 741-0666 or send a request.

Request an Inspection