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Types of Mold – Glossary

Mold Species - Information

All spores found in indoor air are also normally found in outdoor air because most originate or live in the soil and on dead or decaying plants. Therefore, it is not unusual to find mold spores in indoor air. This Mold Glossary is only intended to provide general information about the mold that were found in samples that were sent to the thrid party laboratory.

microscopic image of mold spores

microscopic image of mold spores

Alternaria

  • Outdoor Habitat: One of the most commonly observed spores in the outdoor air worldwide,
    normally in low numbers.
  • Indoor Habitat: Capable of growing on a wide variety of substrates and manufactured products
    found indoors when wetted.
  • Allergy Potential: Type I (hay fever, asthma), Type III (hypersensitivity pneumonitis), Common
    cause of extrinsic asthma
  • Disease Potential: Not normally considered a pathogen, but can become so in
    immunocompromised persons.
  • Toxin Potential: Several known
  • Comments: One of the most common and potent allergens in the indoor and outdoor air.
    Seen in indoor air in low concentrations, probably as a result of outdoor air
    infiltration and/or recycling of settled dust.

Ascospores

  • Outdoor Habitat: Soil and decaying vegetation, dead and dying insects. These spores constitute a
    large part of the spores in the air and can be found in the air in very large
    numbers in the spring and summer, especially during and up to three (3) days
    after a rain.
  • Indoor Habitat: Very few of fungi that produce ascospores grow indoors. Some fungi that
    produce ascospores are recognizable by their spores and when observed are listed
    under their own categories. Wetted wood and gypsum wallboard paper
  • Allergy Potential: Depends on the type of fungus producing the ascospores.
  • Disease Potential: Not normally pathogenic as a group
  • Toxin Potential: None known
  • Comments: Ascospores are produced from a very large group of fungi. Notable ascosporesthat are considered problematic for indoor environments are Chaetomium,Peziza, and Ascotricha. If these types of ascspores are observed they will be listed in the report under their own names.

Basidiospores

  • Outdoor Habitat: These are mushroom spores and are common everywhere outside, especially in
    the late summer and fall.
  • Indoor Habitat: Mushrooms can grow on very wet wood products, especially on footer plates,
    basements, and crawlspaces. Sometimes mushrooms can be observed growing in
    potted plants indoors.
  • Allergy Potential: Rarely reported, but some Type I (hay fever, asthma) and Type III
    (hypersensitivity pneumonitis) has been reported.
  • Disease Potential: None known
  • Toxin Potential: None known
  • Comments: Mushroom spores are commonly found indoors, especially when the outdoor
    spore count is high. When spores of this group are derived from wood rotting
    fungi, including dry rot (Serpula and Poria), they can be especially destructive to
    buildings. When spores from destructive types of mushrooms (dry and wet rot
    group) are observed in the sample they are listed under their own names on the
    report.

 

Bipolaris/Drechslera

  • Outdoor Habitat: Commonly observed spores in the outdoor air worldwide, normally in low
    numbers.
  • Indoor Habitat: Wetted wood and gypsum wallboard paper
  • Allergy Potential: Type I (hay fever, asthma)
  • Disease Potential: Opportunistic pathogen in immunocompromised persons, not normally a
    pathogen in healthy individuals.
  • Toxin Potential: None known
  • Comments: This category represents at least three genera, including Bipolaris, Drechslera,
    and Exserohilum. This group cannot be consistently separated by spore
    morphology alone.

 

Cercospora

  • Outdoor Habitat: Parasitic on leaves
  • Indoor Habitat: Not known to grow indoors
  • Allergy Potential: None known
  • Disease Potential: None known
  • Toxin Potential: None known
  • Comments: Easily dispersed by wind

 

Chaetomium

  • Outdoor Habitat: Commonly found on paper products, soil, decaying vegetation, wood and natural
    fiber textiles (such as jute-backed carpets, canvas, etc.) and similar materials.
    They are rarely identified in outdoor air. These spores can be disseminated by
    insects, wind and water splash, etc. It is also known as a soft-rot fungus for
    softwood and hardwood timber.
  • Indoor Habitat: Chaetomium is often found on a variety of substrates containing cellulose that
    are chronically wetted, including paper documents, wallpaper, textiles and
    construction materials like gypsum board (paper-coated sheet rock) and wood.
    Chaetomium can development quickly, covering a surface with substantial
    growth after two weeks.
    Chaetomium globosum is the most commonly found species indoors. It is not
    that unusual to find the occasional Chaetomium spore in the air indoors.
  • Allergy Potential: Type I (hay fever, asthma) potential. However, no allergens have yet been
    characterised. However, at least two potential allergens have been isolated.
  • Disease Potential: Rarely reported as human pathogen.
  • Toxin Potential: Several known
  • Comments: Chaetomium spores are easily disseminated when it becomes dry. However,
    Chaetomium spores do not remain airborne for long unless disturbed.
    High numbers of spores of this genus is not normal for indoor environments and
    indicate a current or former water problem. Furthermore, since the spores are
    held together by mucilage and trapped by hairs, few become airborne until the
    mold has completely dried out or is mechanically disturbed during renovations
    remediation. It is, therefore, not uncommon to find low Chaetomium spore
    counts in pre-remediation air samples and relatively higher counts in postremediation
    samples.
    Chaetomium species colonize surfaces under similar conditions as Stachybotrys,
    Alternaria, Fusarium and Ulocladium.
    HIGH CONCENTRATIONS AND LONG EXPOSURES TO CHAETOMIUM
    SHOULD BE AVOIDED.

 

Cladosporium

  • Outdoor Habitat: Cladosporium is one of the most common environmental fungi observed
    worldwide and is widely reported from soil and decaying vegetation.
    Cladosporium herbarum and C. cladosporioides are among the most frequently
    encountered species, both in outdoor and indoor environments.
  • Indoor Habitat: Wetted wood and gypsum wallboard paper, paper products, textiles, rubber,
    window sills. Cladosporium has the ability to grow at low temperatures and can
    thus, grow on rubber gaskets and food in refrigerators.
  • Allergy Potential: Type I (hay fever, asthma) - an important and common outdoor allergen
  • Disease Potential: Opportunistic pathogen in immunocompromised persons, not normally a
    pathogen in healthy individuals. Cladosporium are some of the most common
    species reported as indoor contaminants, occasionally linked to health problems.
  • Toxin Potential: Cladosporium has two known toxins (cladosporin and emodin). These toxins are
    not known to be highly toxic. There is no evidence in the literature of toxic effects
    associated to inhalation of Cladosporium conidia (spores) indoors.
  • Comments: The most commonly reported spore in the outdoor air worldwide. This makes
    Cladosporium one of the most commonly reported and abundant spore types
    both indoors and outdoors. The prevalence of this spore can vary throughout the
    year, but is especially high in late summer and autumn, especially where cereal
    crops are commonly planted. An important and common allergen source.

Curvularia

  • Outdoor Habitat: Soil and decaying vegetation
  • Indoor Habitat: Wetted wood and gypsum wallboard paper, many cellulytic substrates
  • Allergy Potential: Type I (hay fever, asthma), common cause of allergenic rhinitis
  • Disease Potential: Potential human pathogen in immunocompromised people
  • Toxin Potential: None known
  • Comments: None

Epicoccum

  • Outdoor Habitat: Epicoccum is a widespread cosmopolitan that grows on dead or decaying organic
    matter, wood, textiles, paper, a variety of foods, insects and human skin. It is
    commonly found in the soil. Epicoccum spores are more prevalent on dry, windy
    days, with higher counts late in the day.
  • Indoor Habitat: Capable of growing on a wide variety of substrates and manufactured products
    found indoors when wetted such as gypsum board, floors, carpets, mattress dust,
    and house plants.
  • Allergy Potential: Type I (hay fever, asthma)
  • Disease Potential: None known
  • Toxin Potential: None known
  • Comments: Very common in outdoor air in the summer months, especially in the midwest
    USA during harvest times.

 

Ganoderma

  • Outdoor Habitat: Growing as a parasite on other plants and fungi, especially on trees, notably
    hardwoods
  • Indoor Habitat: Does not grow indoors
  • Allergy Potential: Type I (hay fever, asthma), rare
  • Disease Potential: None known
  • Toxin Potential: None known
  • Comments: Extensively used as a Chinese herbal supplement

 

Nigrospora

  • Outdoor Habitat: Soil and decaying vegetation
  • Indoor Habitat: Wetted wood and gypsum wallboard paper
  • Allergy Potential: Type I (hay fever, asthma)
  • Disease Potential: None known
  • Toxin Potential: None known
  • Comments: Rarely observed growing indoors

 

Penicillium/Aspergillus

  • Outdoor Habitat: Soil and decaying vegetation, textiles, fruits. These spores are commonly observed
    and are a normal part of outside air.
  • Indoor Habitat: Wetted wood and gypsum wallboard paper, textiles, leather, able to grow on
    many types of substrates.
  • Allergy Potential: Type I (hay fever, asthma), Type III (hypersensitivity pneumonitis)
  • Disease Potential: Opportunistic pathogen in immunocompromised persons, not normally a
    pathogen in healthy individuals.
  • Toxin Potential: Several known
  • Comments: Extremely common in indoor air in low amounts. This type of spore should not
    constitute an overwhelming percentage and be present in very high numbers.
    These two genera are grouped together because they cannot be reliably
    differentiated into their respective genera based solely on spore morphology.

 

Smut/Myxomycetes

  • Outdoor Habitat: Soil and decaying vegetation and wood, especially dead stumps and bark
  • Indoor Habitat: Not known to grow indoors, sometimes found on firewood
  • Allergy Potential: Type I (hay fever, asthma), rare
  • Disease Potential: None known
  • Toxin Potential: None known
  • Comments: These two groups are difficult to distinguish due to their "round, brown"
    morphology. Smuts are especially common in the environment and can be see in
    indoor air samples even during the winter in homes because the spores can get
    trapped in carpets

Spegazzinia

  • Outdoor Habitat: Soil and decaying vegetation, especially in St. Augustine grass
  • Indoor Habitat: Not known to grow indoors
  • Allergy Potential: None known
  • Disease Potential: None known
  • Toxin Potential: None known
  • Comments: A common mold found in St. Augustine grass and other decaying vegetation