Mold analysis

A name in your report.A clearer understanding.

Behind every laboratory finding is a sample, a method, and a property. Explore the handbook to understand the names you see—and the questions worth asking next.

Open the handbook Talk through your results

39 entries · Searchable, practical, and connected.

Smiling clay inspector beside an open reference handbook and microscope. — The detail matters. So does the bigger picture.

The analysis handbook

Find the name.Understand the context.

Explore 39 fungal groups found in environmental reports. Start with a name, then connect the finding to the sample and the setting.

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39 entries

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Browse mold groups Absidia

1 / 39 · Handbook entry

Outdoor sources · Damp materials

Absidia

Soil-associated fungi that can also appear on damp organic materials.

Where it’s found: Outdoor sources include soil and decomposing vegetation. Some species have been recovered from damp, cellulose-rich building materials, food, and settled dust.
What a finding can mean: An indoor finding should be compared with the sampled material and moisture observations. The genus name alone does not show whether growth is occurring inside. Older reports may use Absidia for organisms now classified as Lichtheimia.
Moisture & prevention: Look for wet stored materials, plant debris, or water entry near the sampled area. Correct the moisture source and assess whether affected porous materials can be cleaned or need removal.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Some related Mucorales can cause rare infections, especially in people with weakened immunity or uncontrolled diabetes. A building sample does not diagnose that infection.

Sources & further reading

Damp materials · Specialized identification

Acremonium

Acremonium (incl. A. strictum)

A small-spored group often investigated around persistently wet materials.

Where it’s found: Can occur in soil and plant debris outdoors and in wet building materials, cooling coils, drain pans, window seals, and humidifier water indoors.
What a finding can mean: Small, pale spores can be difficult to distinguish in routine air samples. Spores may remain in moist clusters, so an air result alone can miss a localized reservoir.
Moisture & prevention: Check condensate drainage and the condition of wet insulation or paper-faced materials. Have inaccessible HVAC components assessed by a qualified contractor; resolve recurring wetness before replacing finishes.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Allergic effects and uncommon opportunistic infections have been described. Environmental identification does not establish that a person’s symptoms were caused by Acremonium.

Sources & further reading

Outdoor sources · Damp materials

Alternaria

Alternaria (incl. A. alternata)

A familiar outdoor mold that can also colonize damp indoor surfaces.

Where it’s found: Common on vegetation, soil, and decaying plant material. Indoor growth may occur near condensation, including window frames, showers, paper, and other damp substrates.
What a finding can mean: Outdoor entry and actual surface growth are different findings. Compare the distribution, nearby moisture, and the presence of attached fungal structures before assigning an indoor source.
Moisture & prevention: Address recurring window condensation and bathroom moisture. Check ventilation and clean or replace affected materials as appropriate, rather than repeatedly wiping a stain while the area stays damp.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.

Health context

Alternaria is a recognized allergen and can be relevant to people with mold allergy or asthma. A spore count cannot predict an individual reaction.

Sources & further reading

Outdoor sources · Damp materials

Arthrinium

A plant-associated fungus sometimes found on cellulose materials indoors.

Where it’s found: Natural reservoirs include soil and decaying vegetation. Paper and other cellulose-containing materials can support growth when conditions permit.
What a finding can mean: A few transported spores do not establish a building reservoir. A sample from visible growth, together with material condition and moisture history, is more useful for locating the concern.
Moisture & prevention: Inspect the condition of damp paper, stored cardboard, and wood around the finding. Keep organic debris away from wet building areas and address the source of recurring dampness.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Bulk material examination
A small, agreed portion of material can help characterize growth at that location; it does not represent the whole building.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Allergenic activity is reported for some species. There is no genus-wide toxicity score that translates this finding into a person’s health risk.

Sources & further reading

Outdoor sources · Specialized identification

Ascospores

A broad spore category, rather than the name of one mold.

Where it’s found: Produced by many fungi associated with plants, soil, and decomposing material. Some indoor-growing fungi also produce ascospores, so the category spans very different habitats.
What a finding can mean: An “ascospores” line on a report may describe appearance without identifying the genus. Outdoor conditions, ventilation, and other findings matter; the label alone does not prove an indoor leak or an outdoor-only source.
Moisture & prevention: Review the sample context before taking action. Where moisture or visible growth is present, investigate that location rather than trying to eliminate every naturally occurring airborne spore.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Further identification
If a more specific identification would change a decision, discuss a suitable sample and laboratory method first.

Health context

This broad category cannot carry one health rating. Interpretation depends on the organism, exposure circumstances, and individual susceptibility.

Sources & further reading

Damp materials · Dust & stored materials · Specialized identification

Aspergillus

Aspergillus (all species)

A diverse genus whose small spores often share a reporting category with Penicillium.

Where it’s found: Found in soil, plant debris, food, dust, and many indoor materials. Moisture requirements vary by species; some can grow at lower water availability than molds associated with very wet materials.
What a finding can mean: Routine spore-trap microscopy commonly reports an Aspergillus/Penicillium-like group. That result cannot identify a particular Aspergillus species or demonstrate mycotoxin production.
Moisture & prevention: Connect the sample to moisture measurements, dust reservoirs, and affected materials. Fix damp conditions and evaluate actual growth; choose any additional species-level work around a defined question.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Targeted PCR
Consider only when the laboratory panel includes the relevant target. DNA detection does not establish viability, toxin production, or a health effect.

Health context

Some species are important allergens or can cause infections in susceptible people. A genus-level environmental result does not show that disease or toxin exposure has occurred.

Sources & further reading

Damp materials · Outdoor sources

Aureobasidium

Aureobasidium (A. pullulans)

A yeast-like fungus often associated with frequently damp surfaces.

Where it’s found: Occurs on plants and wood outdoors. Indoors, it can colonize surfaces around moisture accumulation, including painted finishes, window areas, grout, and sealants.
What a finding can mean: Pink, brown, or dark discoloration is not enough to identify it. A surface examination can help distinguish fungal growth from an unrelated stain and put the finding at a specific location.
Moisture & prevention: Look for condensation or recurrent wetting around the finish. Correct the cause, clean suitable surfaces, and assess damaged porous materials before refinishing.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Swab sampling
Collects material from an agreed surface for the selected laboratory method. The result is specific to that sample and question.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Allergic reactions have been described. A surface finding does not determine the cause of a rash or respiratory symptom; persistent symptoms need clinical evaluation.

Sources & further reading

Outdoor sources · Specialized identification

Basidiospores

Spores from a broad group that includes mushrooms and many wood-associated fungi.

Where it’s found: Often originate outdoors from fungi on lawns, trees, and decaying wood. Some members can grow on wood within buildings where moisture and other conditions are suitable.
What a finding can mean: The presence of basidiospores indoors does not by itself establish hidden rot. Consider outdoor comparison samples, weather, and physical evidence of damp or deteriorated wood.
Moisture & prevention: If the inspection finds wood damage, locate the water source and assess the material directly. Air filtration can reduce incoming particles but does not repair a wet structure.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Bulk material examination
A small, agreed portion of material can help characterize growth at that location; it does not represent the whole building.

Health context

Allergenic effects vary across this large group. The reporting category does not identify a specific organism or provide a health-based indoor limit.

Sources & further reading

Outdoor sources · Specialized identification

Bipolaris / Drechslera / Exserohilum

Related-looking dark spores that laboratories may report together.

Where it’s found: These genera are associated with soil, grasses, and other plants. Outdoor particles can enter buildings and settle in dust; some can also occur on indoor materials.
What a finding can mean: A combined reporting group is an identification limit, not confirmation of all three genera. Source interpretation needs the indoor/outdoor pattern and any evidence of growth on sampled surfaces.
Moisture & prevention: Review nearby plant material, dust entry, and localized dampness. Maintain appropriate filtration and correct documented wet conditions instead of treating an air category as proof of widespread growth.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Some members are associated with allergy and occasional infections. A combined environmental category cannot establish which organism, exposure, or health effect is present.

Sources & further reading

Outdoor sources · Damp materials

Botrytis

A plant-associated mold often considered around damp vegetation and produce.

Where it’s found: Commonly associated with flowers, fruit, vegetables, and other plant material. Indoor plant areas and greenhouses can provide suitable moist conditions.
What a finding can mean: Look at potential plant or food reservoirs before assuming the building structure is colonized. Airborne spores may be transported from a source away from the collection point.
Moisture & prevention: Remove decaying plant material, avoid overwatering, and review airflow and humidity around plant displays or storage. Investigate building materials separately if they are also damp.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.

Health context

Allergic effects have been reported. The presence of this genus in a property sample does not predict symptoms or establish an individual diagnosis.

Sources & further reading

Damp materials

Chaetomium

Chaetomium (incl. C. globosum)

A cellulose-associated fungus that can help focus a water-damage investigation.

Where it’s found: Can grow on wet paper, paper-faced gypsum board, cardboard, and wood. It also occurs outdoors in soil and decomposing plant material.
What a finding can mean: A finding on affected building material supports looking closely at its moisture history. Detection does not date the leak, show that it is still active, or quantify a person’s exposure.
Moisture & prevention: Investigate the extent of wet cellulose materials and the route of water entry. Plan appropriate cleaning or removal of affected materials together with drying and repair.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Bulk material examination
A small, agreed portion of material can help characterize growth at that location; it does not represent the whole building.
Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.

Health context

Some species can produce mycotoxins under suitable conditions. Identifying Chaetomium does not establish that toxins were produced or caused symptoms.

Sources & further reading

Outdoor sources · Specialized identification

Chrysosporium

A soil-associated group for which careful identification matters.

Where it’s found: Found in soil and on organic material. Some members use keratin-containing debris such as hair and skin; this is a different context from growth through damp drywall.
What a finding can mean: A reported isolate should be considered with the sample substrate and laboratory identification method. Presence in dust is not enough to identify a building-wide reservoir.
Moisture & prevention: Review housekeeping, tracked-in soil, and accumulated organic debris around the sampled spot. Investigate wet materials when observed, rather than inferring them from the name alone.

Sampling & analysis

Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Swab sampling
Collects material from an agreed surface for the selected laboratory method. The result is specific to that sample and question.

Health context

Uncommon infections are described in medical literature. An environmental sample does not establish infection or justify a personal health conclusion.

Sources & further reading

Outdoor sources · Damp materials

Cladosporium

Cladosporium (incl. C. cladosporioides, C. herbarum, C. sphaerospermum)

A common outdoor and indoor genus whose source depends on the setting.

Where it’s found: Occurs on plants and in outdoor air, and may grow on damp painted surfaces, textiles, wood, or insulation indoors. Condensation can provide moisture at a surface even without a plumbing leak.
What a finding can mean: An indoor result can reflect incoming outdoor spores, a local reservoir, or both. Compare the sampling conditions with visible growth and moisture patterns; color alone does not identify the genus.
Moisture & prevention: Check recurring condensation, wet fabrics, and affected finishes. Correct moisture and clean or replace materials as appropriate before painting or sealing.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Cladosporium is a recognized allergen. Its common occurrence does not make indoor growth something to ignore, and a count cannot predict an individual asthma or allergy response.

Sources & further reading

Outdoor sources · Specialized identification

Curvularia

A dark-spored fungus commonly associated with soil and plant material.

Where it’s found: Outdoor soil, grasses, and plant debris are typical reservoirs. Spores can be transported indoors and become part of settled dust.
What a finding can mean: Consider outside entry and nearby organic material alongside any damp indoor surface. Finding Curvularia in dust does not, by itself, show that an HVAC system is colonized.
Moisture & prevention: Review dust sources and the condition of filters and accessible equipment. Use moisture findings to guide any building-material investigation or HVAC referral.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Allergy and uncommon infections have been associated with some members. Medical relevance depends on the person and clinical evidence, not a building report alone.

Sources & further reading

Outdoor sources · Damp materials

Epicoccum

Epicoccum (E. nigrum)

A plant-associated fungus that can also occur on damp cellulose materials.

Where it’s found: Common on dead plant matter and in soil. Indoors, suitable damp paper, textiles, and building materials can support growth.
What a finding can mean: Outdoor entry is a plausible source of isolated spores. A finding attached to visibly affected material gives different information from a few spores collected in room air.
Moisture & prevention: Check damp paper-faced materials and stored items near the finding. Address moisture and remove deteriorated material where needed; an orange or dark stain alone is not an identification.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.

Health context

Epicoccum is associated with allergic responses in susceptible people. The genus name cannot predict severity or explain symptoms without medical evaluation.

Sources & further reading

Specialized identification

Epidermophyton

A dermatophyte, with a different meaning from ordinary building mold.

Where it’s found: Associated primarily with human skin and nails. Shed skin can transfer the organism to shared items or surfaces; this is not the usual pattern of moisture-driven growth on building materials.
What a finding can mean: If reported in an environmental sample, verify the sample history and identification with the laboratory. Do not automatically call it contamination or assume that a room sample diagnoses a person.
Moisture & prevention: For a suspected skin or nail infection, seek a clinician’s assessment. Cleaning of shared surfaces and hygiene should follow the relevant guidance; a routine mold survey is not a medical test.

Sampling & analysis

Specialized laboratory discussion
Discuss the purpose and sample type before arranging testing; routine environmental spore traps are not a clinical diagnostic method.

Health context

Epidermophyton can cause forms of ringworm. Diagnosis and treatment require clinical assessment rather than an environmental mold result.

Sources & further reading

Dust & stored materials · Specialized identification

Eurotium

Eurotium (E. chevalieri, E. repens)

A traditional name used for certain Aspergillus-related fungi.

Where it’s found: Associated with stored foods, dust, and indoor materials. Members can tolerate lower water availability than many other fungi, but they still need suitable conditions to grow.
What a finding can mean: “Dry-tolerant” does not mean growth occurs with no moisture. A recurring finding may prompt a review of storage conditions and humidity; confirm how the laboratory uses this older name.
Moisture & prevention: Inspect stored items and dust reservoirs for actual growth or deterioration. Keep food appropriately stored and address sustained humidity rather than looking only for a major leak.

Sampling & analysis

Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Targeted PCR
Consider only when the laboratory panel includes the relevant target. DNA detection does not establish viability, toxin production, or a health effect.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.

Health context

A taxonomic name does not establish toxin exposure or illness. Discuss individual respiratory or allergy concerns with a healthcare professional.

Sources & further reading

Outdoor sources · Damp materials · Specialized identification

Fusarium

A diverse plant and soil group also encountered in wet environments.

Where it’s found: Common on plants and in soil. Indoors, it may be found around wet organic materials, water-damaged finishes, or persistently damp equipment.
What a finding can mean: The genus includes many organisms with different properties. A surface or culture result should be linked to its sampled location; it cannot establish a food-toxin exposure or a medical infection.
Moisture & prevention: Investigate ongoing wetness, water entry, and the condition of affected porous materials. Maintain water-containing equipment according to its instructions and resolve the source of recurrent moisture.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Targeted PCR
Consider only when the laboratory panel includes the relevant target. DNA detection does not establish viability, toxin production, or a health effect.

Health context

Some species are opportunistic pathogens, particularly for vulnerable people. Identification in a building is not evidence that a person has an infection.

Sources & further reading

Damp materials · Specialized identification

Geotrichum

A yeast-like fungus whose fragments can require further identification.

Where it’s found: Associated with soil, plant matter, and food. Damp organic residues or wet equipment may provide indoor reservoirs.
What a finding can mean: Geotrichum produces arthroconidia through fragmentation of fungal filaments. Similar particles from other organisms can complicate direct identification, so the laboratory method and report wording matter.
Moisture & prevention: Check the sampled material and any nearby food or organic residue. Investigate a wet equipment component directly rather than assuming an air finding identifies its source.

Sampling & analysis

Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Swab sampling
Collects material from an agreed surface for the selected laboratory method. The result is specific to that sample and question.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.

Health context

Clinical infections are uncommon and require a medical diagnosis. A property sample cannot establish that this organism is responsible for symptoms.

Sources & further reading

Outdoor sources · Specialized identification

Helminthosporium

A name that needs context because older reports may use it broadly.

Where it’s found: Associated with plants, wood, and soil. Some fungi historically included under this name are now placed in other genera.
What a finding can mean: Ask whether the report means a confirmed genus or a broader appearance-based category. Do not equate an older name with a specific species or a particular source inside the building.
Moisture & prevention: Review nearby vegetation and outdoor entry alongside the material and moisture findings. If the exact identity would change the next step, clarify it with the laboratory.

Sampling & analysis

Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Air sampling context
An air report may group similar dark, multicelled spores. Read the laboratory’s category definitions before comparing names.

Health context

Health conclusions cannot be drawn from an ambiguous or historical reporting label. A clinician should assess health concerns separately.

Sources & further reading

Damp materials · Specialized identification

Memnoniella

A cellulose-associated mold often discussed alongside Stachybotrys.

Where it’s found: Can occur on damp paper and other cellulose-rich materials. Outdoor plant material is another possible source.
What a finding can mean: A finding at a damaged material can help focus the moisture investigation. Related-looking spores may share a reporting category, and detection cannot establish the duration of a leak.
Moisture & prevention: Examine wet paper-faced finishes and adjacent materials. Address water entry and assess the extent of growth before deciding the appropriate remediation scope.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Bulk material examination
A small, agreed portion of material can help characterize growth at that location; it does not represent the whole building.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Potential toxin production is not the same as measured toxin exposure. A report naming this group does not prove that it caused a symptom or illness.

Sources & further reading

Damp materials · Specialized identification

Microascus

A group with a close reporting and taxonomic connection to Scopulariopsis.

Where it’s found: Occurs in soil and plant-associated material. It has also been reported from wood and drywall indoors.
What a finding can mean: The name may appear alongside Scopulariopsis in laboratory categories. Interpret the reported level of identification and sampled substrate before drawing conclusions about a building source.
Moisture & prevention: Check the actual condition of the sampled wood or drywall. Investigate nearby moisture and deterioration; the organism name alone does not demonstrate structural rot.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Rare opportunistic infections are described. Environmental detection cannot establish infection, exposure dose, or a numerical toxicity level.

Sources & further reading

Specialized identification

Dermatophytes

Microsporum / Trichophyton / Epidermophyton (group)

A group associated with skin, hair, and nails rather than a typical moisture survey.

Where it’s found: Different dermatophytes are associated with people, animals, or soil. Organisms may be carried on shed skin or hair and transferred through shared items and surfaces.
What a finding can mean: This group is retained to help readers interpret unfamiliar report names. An environmental finding is not automatically a sampling error, but it is also not a diagnosis of ringworm.
Moisture & prevention: Clarify why this group was tested and whether the method fits the question. Direct suspected infection in a person or pet to an appropriate healthcare or veterinary professional.

Sampling & analysis

Discuss the testing purpose
Specialized environmental and clinical questions require different sampling pathways. Establish the question before collecting a specimen.

Health context

These fungi can cause skin, hair, or nail infections. Clinical examination and, where needed, clinical specimens are distinct from property mold testing.

Sources & further reading

Outdoor sources · Damp materials

Mucor

Mucor (incl. M. hiemalis, M. racemosus)

A fast-growing environmental mold found in organic materials.

Where it’s found: Occurs in soil, decomposing vegetation, and spoiled foods. Damp organic materials indoors can also support growth.
What a finding can mean: Loose spores may not identify the genus precisely on a routine spore trap. Intact structures or an appropriate culture can provide more information when a defined question warrants it.
Moisture & prevention: Check food waste and damp organic items around the sampled area. Respond to water damage and evaluate affected materials rather than using the name as a stand-alone measure of severity.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Some Mucorales cause rare, serious infections, mainly in susceptible people. Their environmental occurrence is much more common than disease; a room sample is not a medical test.

Sources & further reading

Outdoor sources

Nigrospora

A plant-associated fungus whose dark spores may appear in environmental samples.

Where it’s found: Commonly associated with grasses and other plant material, soil, and organic debris. Spores can be carried indoors with air or dust.
What a finding can mean: An indoor spore finding does not automatically mean indoor growth or excessive humidity. Compare it with outdoor sources and direct observations of the sampled space.
Moisture & prevention: Check relevant plant debris and dust pathways. Follow up on a specific damp surface if one is observed, rather than treating every detection as a hidden building problem.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Allergenic potential is described for this genus. Individual health significance cannot be determined from a property sample alone.

Sources & further reading

Damp materials · Dust & stored materials · Specialized identification

Paecilomyces

Paecilomyces (P. variotii)

A group that can resemble other small-spored molds in routine samples.

Where it’s found: Occurs in soil and decaying organic material, and may be found in dust or on affected indoor materials. Species differ in their preferred growth conditions.
What a finding can mean: An air particle may not be distinctive enough for genus-level identification. “Paecilomyces” should not be treated as proof of a major leak without corresponding field evidence.
Moisture & prevention: Review affected stored materials and any documented water damage. If identification affects the next step, agree on a method capable of providing that detail.

Sampling & analysis

Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Targeted PCR
Consider only when the laboratory panel includes the relevant target. DNA detection does not establish viability, toxin production, or a health effect.

Health context

Some members are opportunistic pathogens; this does not mean a property finding establishes disease. Personal health concerns belong with a clinician.

Sources & further reading

Damp materials · Dust & stored materials · Specialized identification

Penicillium

Penicillium (all species)

A common genus whose airborne spores are often grouped with Aspergillus.

Where it’s found: Found in dust, food, and a range of building materials. Damp paper, finishes, and stored items can provide indoor reservoirs, while outdoor sources also contribute spores.
What a finding can mean: An Aspergillus/Penicillium-like count does not identify all the organisms represented. Compare the result with the inspection and sampling method before considering targeted follow-up.
Moisture & prevention: Look for moisture-affected items and materials, including stored cardboard or finishes near a leak. Correct the wetting source and address the affected material; dust removal alone cannot fix active growth.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Targeted PCR
Consider only when the laboratory panel includes the relevant target. DNA detection does not establish viability, toxin production, or a health effect.

Health context

Allergic effects are possible, and some species can produce mycotoxins in particular conditions. A genus or combined spore category does not demonstrate toxin exposure.

Sources & further reading

Outdoor sources · Damp materials · Specialized identification

Phoma

A plant-associated name that can also appear in damp-building investigations.

Where it’s found: Found on plants and in soil. Some members have been recovered from damp painted finishes, paper, and other cellulose-containing materials indoors.
What a finding can mean: The group has undergone taxonomic changes, so newer reports may use different names. Small spores alone can lack the structures needed for a confident genus identification.
Moisture & prevention: Check localized dampness and the affected finish. Clean and dry appropriate materials before repainting; recurring discoloration calls for investigation of the moisture source.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Reported health effects vary by organism and circumstance. A Phoma-like environmental finding is not a diagnosis or a measure of personal toxicity.

Sources & further reading

Outdoor sources · Damp materials

Pithomyces

A fungus associated with leaf litter that can occur on damp paper.

Where it’s found: Natural reservoirs include soil, tree bark, and decaying leaves. Paper is one reported indoor substrate, and moisture is important for germination.
What a finding can mean: Airborne spores may come from outdoor material. If a report adds a symbol such as “++,” check whether the category includes other similar-looking spores.
Moisture & prevention: Review outdoor debris and any damp paper products near the concern. Connect the finding to an actual source before choosing a cleaning or repair scope.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Some species have documented metabolites, but identifying the genus does not establish toxin production or a person’s exposure. No toxicity rank follows from the name.

Sources & further reading

Outdoor sources · Damp materials · Dust & stored materials

Rhizopus

Rhizopus (incl. R. stolonifer, R. oryzae)

A fast-growing genus familiar from spoiled food and damp organic material.

Where it’s found: Occurs in soil, decomposing plants, and foods such as bread or fruit. Suitable damp materials indoors can also support growth.
What a finding can mean: Sporangia and other intact structures can distinguish this group better than isolated particles. An environmental finding does not identify a medical infection or show that all nearby material is affected.
Moisture & prevention: Review spoiled food and wet organic materials. Correct water intrusion and assess the extent of any building growth rather than basing removal on a genus label alone.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Rhizopus includes species associated with rare mucormycosis, particularly in susceptible people. A healthcare professional evaluates that concern using clinical evidence.

Sources & further reading

Damp materials · Specialized identification

Rhodotorula

A pigmented yeast that needs more than color for identification.

Where it’s found: Found in water, soil, and other environmental settings. Persistently damp indoor surfaces or equipment may support yeast growth.
What a finding can mean: Pink or orange residue has several possible causes, including organisms outside this genus. Routine mold-spore counting may report yeasts without identifying Rhodotorula.
Moisture & prevention: Check why the sampled surface remains wet and review cleaning and equipment maintenance. Resolve recurring moisture rather than using a color match as a diagnosis.

Sampling & analysis

Swab sampling
Collects material from an agreed surface for the selected laboratory method. The result is specific to that sample and question.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Opportunistic infections occur in particular clinical circumstances. Finding a pigmented yeast on a surface does not establish that risk for an occupant.

Sources & further reading

Damp materials · Specialized identification

Scedosporium

A specialized identification that should be interpreted with the sample context.

Where it’s found: Associated with soil, organic matter, and water-impacted environments. The significance of an indoor isolate depends on where and how it was collected.
What a finding can mean: Confirm the laboratory’s identification and the purpose of testing. One detection is not enough to determine the extent of contamination or prescribe whole-building material removal.
Moisture & prevention: Investigate documented water damage and the sampled reservoir. Agree on targeted follow-up and an appropriate response to the actual condition of the property.

Sampling & analysis

Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Swab sampling
Collects material from an agreed surface for the selected laboratory method. The result is specific to that sample and question.

Health context

Some species can cause opportunistic infections in susceptible people. A laboratory result from a building cannot diagnose infection or determine its treatment.

Sources & further reading

Damp materials · Dust & stored materials · Specialized identification

Scopulariopsis

Scopulariopsis (S. brevicaulis)

A soil and material-associated group sometimes reported with Microascus.

Where it’s found: Can occur in soil, dust, and organic materials, including paper-faced finishes. Its presence should be interpreted with the particular sample and material condition.
What a finding can mean: Related taxa may appear under a combined category. Neither an odor nor this identification establishes arsenic in wallpaper, a toxic gas, or a specific building-wide hazard.
Moisture & prevention: Assess damp paper-faced materials and dust reservoirs around the finding. Any concern about historic building chemicals requires its own appropriate assessment rather than inference from a mold name.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Targeted PCR
Consider only when the laboratory panel includes the relevant target. DNA detection does not establish viability, toxin production, or a health effect.

Health context

Some species have been associated with nail and other opportunistic infections. A property sample does not diagnose a person or establish toxin exposure.

Sources & further reading

Damp materials

Stachybotrys

Stachybotrys (Black Mold)

A moisture-associated mold; “black mold” is not a reliable visual identification.

Where it’s found: Stachybotrys chartarum can grow on cellulose-rich materials such as gypsum-board paper, fiberboard, and paper when those materials remain wet.
What a finding can mean: The finding can focus attention on a wet material, but it cannot date the growth or show whether the source is still active. Dark coloration alone does not identify Stachybotrys.
Moisture & prevention: Find and correct the moisture source and assess affected material for appropriate cleanup or removal. Address mold growth regardless of its color or whether a species name is available.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Bulk material examination
A small, agreed portion of material can help characterize growth at that location; it does not represent the whole building.
Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.

Health context

Like other indoor molds, Stachybotrys growth should be addressed. CDC notes that no test proves a link between this mold and particular symptoms; the name alone does not establish a cause of illness.

Sources & further reading

Outdoor sources · Damp materials

Stemphylium

A plant-associated fungus that may appear among dark, multicelled spores.

Where it’s found: Commonly associated with vegetation and plant debris. Damp cellulose materials can be relevant indoor substrates when growth is actually present.
What a finding can mean: Spore appearance can overlap with related categories. A report should be read at the identification level the laboratory supports, not automatically treated as species confirmation.
Moisture & prevention: Compare outdoor sources with the condition of any damp paper or building material nearby. Correct observed moisture rather than treating an isolated spore as proof of a hidden reservoir.

Sampling & analysis

Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Allergenic effects have been described. A genus-level finding cannot predict the severity of an individual reaction.

Sources & further reading

Damp materials · Outdoor sources

Trichoderma

Trichoderma (T. viride)

A fungus associated with soil, wood, and damp cellulose materials.

Where it’s found: Occurs outdoors in soil and decomposing organic matter. Wet paper-faced finishes, wood, and other moisture-affected indoor materials can also support growth.
What a finding can mean: Small spores may not be uniquely identifiable in a routine air count. Finding growth on a material is different from detecting transported spores, and a name alone cannot establish structural damage.
Moisture & prevention: Check the condition of wet porous materials and the cause of recurring dampness. Decide on drying, cleaning, or replacement from the actual extent and material condition.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Targeted PCR
Consider only when the laboratory panel includes the relevant target. DNA detection does not establish viability, toxin production, or a health effect.

Health context

Species differ in their properties. Identification does not establish toxin production, exposure dose, or a cause of respiratory symptoms.

Sources & further reading

Damp materials · Outdoor sources · Specialized identification

Ulocladium

A name often associated with wet cellulose materials and related spore groups.

Where it’s found: Occurs in soil and decaying vegetation. Indoor growth can occur on wet gypsum-board paper, paint, textiles, and window-area materials.
What a finding can mean: Young or fragmented spores may overlap in appearance with Alternaria or Pithomyces. Read combined categories carefully; the image or dark color cannot establish identity.
Moisture & prevention: Review sustained dampness at windows, bathrooms, or affected finishes. Fix leakage or condensation and address the material itself rather than covering over the growth.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.

Health context

Allergenic effects are reported. It should not be ranked as a “safer black mold”; any indoor growth merits attention to its source and extent.

Sources & further reading

Dust & stored materials · Specialized identification

Wallemia

Wallemia (W. sebi)

A dry-tolerant fungus that makes storage conditions and humidity relevant.

Where it’s found: Associated with soil, hay, stored foods, and dust or other indoor materials. It can grow at lower water availability than many molds, under suitable conditions.
What a finding can mean: Lower moisture requirements do not mean that completely dry dust automatically grows mold. Review humidity history and the sampled material; routine methods may not distinguish its small spores reliably.
Moisture & prevention: Check stored items and dust accumulation where humidity persists. Improve moisture control and housekeeping together, rather than assuming that the absence of a major leak rules out growth.

Sampling & analysis

Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Targeted PCR
Consider only when the laboratory panel includes the relevant target. DNA detection does not establish viability, toxin production, or a health effect.
Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.

Health context

Allergic effects have been described, including in particular occupational exposures. An indoor detection does not establish a person’s illness or its cause.

Sources & further reading

Outdoor sources · Damp materials · Specialized identification

Zygomycetes

Zygomycetes (group incl. Mucor, Rhizopus, Absidia)

A traditional broad label that may include Mucor, Rhizopus, and related fungi.

Where it’s found: The members represented in environmental reports commonly occur in soil, foods, and decaying organic matter. Damp indoor organic materials can provide growth sites.
What a finding can mean: This historical grouping is not a single genus or species. Ask what the laboratory included in the category, especially before comparing results that use newer or more specific names.
Moisture & prevention: Focus on the sampled material and observed water damage. Address wet organic reservoirs and correct moisture; select additional identification only if it will answer a useful question.

Sampling & analysis

Tape lift / surface examination
Examines the sampled spot for fungal structures. Intact growth can provide more context than loose spores alone.
Culture analysis
May support further identification when organisms grow on the selected media. Recovery depends on the organism and incubation conditions.
Spore trap analysis
A snapshot of airborne particles. Similar-looking spores may be grouped; this does not establish species or viability.

Health context

Some members of Mucorales cause rare infections in susceptible people. A broad environmental category does not establish a clinical diagnosis or personal risk score.

Sources & further reading

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The colony illustrations are browsing aids. Identification comes from the laboratory method and findings.

Reading the report

The finding is a start.Context brings it together.

A useful explanation connects the laboratory result with what was observed in your property.

How inspection adds context

What does the name on my report tell me?

Identification depends on the analytical method. A report may name a broad spore group, a genus, or a species. Similar-looking spores may be grouped together. Read that name alongside the sample type and the laboratory’s comments before drawing a conclusion.

Can a spore count tell me whether a room is safe?

A count describes the submitted sample under a particular method. There are no federal airborne mold limits or health-based indoor-air standards that turn a count into a universal safe-or-unsafe result. The collection conditions, inspection findings, and moisture history matter.

Does every visible mold problem need laboratory testing?

No. Visible growth and moisture problems often need attention without identifying the mold first. Sampling is useful when it answers a defined question. Discuss what the result would change before choosing a collection and analysis method.

What should I bring to a conversation about my results?

Bring the complete report, sample locations, collection date, and any photographs or leak history. We can explain how the findings relate to the property and which questions may need further investigation. Health questions belong with a qualified healthcare professional.

Guidance from EPA and CDC / NIOSH.

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