A zygomycete fungus. Reported to be allergenic. May cause mucorosis in immune compromised individuals. The sites of infection are the lung, nasal sinus, brain, eye and skin. Infection may have multiple sites.

Acremonium (Cephalosporium)

Reported to be allergenic. Can produce a trichothecene toxin that is toxic if ingested. It was the primary fungus identified in at least two houses where the occupant complaints were nausea, vomiting and diarrhea. Asexual state of Emericellopsis sp., Chaetomium sp., and Nectripsis sp. It can produce mycetomas, infections of the cornea and nails.


Aw – 0.89. Conidia dimensions: 18-83 x 7-18 microns. This is one of the main fungal causes of allergy, being a common type I (ex.: hay fever, asthma) & type III (ex.: hypersensitivity pneumonitis) allergen. The large spore size suggests that this fungus will settle in the nose, mouth, and upper respiratory tract, causing nasal septum infections. Alternaria is a common cause of extrinsic asthma, with acute symptoms including edema and bronchiospasms; chronic cases may develop pulmonary emphysema. “Baker’s asthma” is commonly associated with inhalation of Alternaria conidia present in flour. Other diseases caused by this mold include: “farmer’s lung”, “woodworker’s lung”, “apple store hypersensitivity”, mycotic keratitis (fungal infection of the cornea), nasal lesions, subcutaneous lesions, skin infections, nail infections, and osteomyelitis (inflammation of the bone). [It should be noted that most of the reported infections affected persons with underlying disease or those taking immunosuppressive drugs.]

Toxic metabolites (that may cause disease in humans) produced by these microbes include AME (alternariol monomethylether), tenuazonic acid, and altertoxins (which are mutagenic). Several species are pathogenic to plants, and some are processed for use in the biocontrol of weeds and other plants. A. alternata produces alternariol, an antifungal metabolite.

Alternaria is commonly found indoors in dust, carpeting, textiles, on foodstuffs, and horizontal surfaces (such as window frames). It has also been isolated from substrates such as sewage, leather, stone monuments, optical instruments, cosmetics, computer disks, and even jet fuel. Outdoors, it may be found on dead organic debris, seeds, plants (and can contribute to the spoilage of agricultural products), in soil, and air–one of the reasons that it is a widespread genus. Alternaria conidia are easily carried by the wind, with peak air concentrations occurring in the summer and early fall. Colonies grow fast, are suede-like to floccose, and black to olivaceous-black or grayish in color.


A spherical or oval single-celled fungal spore that is practically unidentifiable by itself. Genera with this type of spore include, but are not limited to, Aspergillus, Penicillium, and Trichoderma.

For example, Penicillium is easily identifiable when sampling using culturing techniques. However, when sampling with non-culturing techniques, such as spore traps or tape-lifts, the free spores with no remnants of the fungal structure are indistinguishable from Aspergillus and various other genera that also produce small round and oval spores with little or no pigmentation. Due to this fact, Penicillium will often be categorized on laboratory reports in an “amerospore” and/or “Aspergillus/Penicillium” group.


Widespread saprophyte found on decomposing plant material, particularly grasses, and on soil. It is a white, fuzzy mold. It should be considered to be an allergen. This fungus has also been documented in various subcutaneous infections. No diseases related to toxic effects have been recorded to date.


A spore borne in a special cell called an ascus. Spores of this type are reported to be allergenic.

All ascomycetes, members of a group of fungi called Ascomycotina, have this type of spore. The minute black dots on rotting wood and leaves or the little cups on lichens are examples of ascomycetes; another is the “truffle” mushroom.

Aspergillus Caesiellus

This species is only occasionally pathogenic.

Aspergillus Candidus

Aw 0.75. Conidia dimensions: 2.5-4 microns. Found in warm soils, grain and in the secondary decay of vegetation. Associated with respiratory complaints in a recent house investigation. Can produce the toxin petulin that may be associated with disease in humans and other animals.

Aspergillus Carneus

This species is only occasionally pathogenic.

Aspergillus Clavatus

Conidia dimensions: 3-4.5 x 2.5-4.5 microns. Found in soils and animal manure.
Can produce the toxin petulin that may be associated with disease in humans and other animals. This species is only occasionally pathogenic.

Aspergillus Deflectus

This species is only occasionally pathogenic.

Aspergillus Flavus

Aw 0.78. Conidia dimensions: 3-6 microns or 3-5 microns. It grows on moldy corn and peanuts. It can be found in warm soil, foods and dairy products. Some strains are capable of producing a group of mycotoxins- in the aflatoxin group. Aflatoxins are known animal carcinogens. There is limited evidence to suggest that this toxin is a human carcinogen. The toxin is poisonous to humans by ingestion. It may also result in occupational disease via inhalation. Experiments have indicated that it is teratogenic and mutagenic. It is toxic to the liver. It is reported to be allergenic. Its presence is associated with reports of asthma. It can be found in water-damaged carpets. The production of the fungal toxin is dependent on the growth conditions and on the substrate used as a food source. This fungus is associated with aspergillosis of the lungs and/or disseminated aspergillosis. This fungus is occasionally identified as the cause of corneal, otomycotic and nasoorbital infections.

Aspergillus Fumigatus

Aw 0.82; Optimum> 0.97. Conidia dimensions: 2-3.5 microns. Considered a human pathogen, this organism causes both allergic aspergillosis and invasive aspergillosis (invasive aspergillosis usually affects individuals who are immune compromised). It is commonly found outdoors on cereal grains, in cool to warm soils, and in compost piles (even with temperatures exceeding 40 degrees C).

Aspergillus Glaucus

Conidia dimensions: 5-6.5 microns. Common outdoor fungus in the winter. It is reported to be allergenic. This species is only occasionally pathogenic. It can grow on leather. This fungus can grow at low moisture levels on grains, sugary food products, meat and wool. The ascomycetous state is Eurotium sp.

Aspergillus Nidulans

Aw 0.78. Conidia dimensions: 2-4 microns. Found in mild to warm soils and on slowly decaying plants. Can produce the mycotoxin sterigmatocystin. This toxin has been shown to produce liver and kidney damage in lab animals. This fungus is associated with aspergillosis of the lungs and/or disseminated aspergillosis. This species is only occasionally pathogenic.

Aspergillus Niger

Aw 0.77; Optimum> 0.97. Conidia dimensions: 3.5 – 5 microns or 4 to 5 microns. Less common cause of aspergillosis. It has a musty odor. It is commonly found in the environment on textiles, in soils, grains, fruits and vegetables. It has been reported to cause skin and pulmonary infections. It is a common cause of fungal related ear infections, including otomycosis.

Aspergillus Ochraceus

Aw 0.77. Conidia dimensions: 2.5 – 3 microns. Found in grains, soil and salted food products. It is not usually associated with decaying vegetation. Can produce a kidney toxin ochratoxin A that may produce ochratoxicosis in humans. This is also known as Balkan nephropathy. The toxin is produced at optimum growth conditions at 25 degrees C and high moisture conditions. The ochratoxin may also be produced by other Aspergillus sp. and Penicillium sp. Other toxins that can be produced by this fungus include penicillic acid, xanthomegnin and viomellein. These are all reported to be kidney and liver toxins.

Aspergillus Oryzae

This species is only occasionally pathogenic.

Aspergillus Parasiticus

Some strains are capable of producing a group of mycotoxins- in the aflatoxin group. Aflatoxins are known animal carcinogens. There is limited evidence to suggest that this toxin is a human carcinogen. The toxin is a poisonous to humans by ingestion. Experiments have indicated that it is teratogenic and mutagenic. It is toxic to the liver. The production of the fungal toxin is dependent on the growth conditions and on the substrate used as a food source.

Aspergillus / Penicillium-Like

This category is included on laboratory analysis reports for air samples containing certain free spores without other identifying structures. The free spores of Aspergillus and Penicillium (and other genera with small, round or ovoid, and colorless spores) are essentially indistinguishable, using standard microscopic examination methods.

If required, cultured specimens can provide additional characteristics that will enable technicians to determine what genus is represented. If sporulating structures are present, Aspergillus is readily identifiable on tape samples. [Discovery of the Aspergillus species requires the culture of the fungus under different conditions of media, humidity, and temperature. Identifying Penicillium species is difficult, but, in some cases, possible.]

These two allergenic molds are among those most often found in contaminated buildings. Aspergillus is represented by numerous species, many of which produce toxic substances. It may be associated with symptoms such as sinusitis, allergic bronchiopulmonary aspergillosis, and other allergic symptoms. As if not to be outdone, Penicillium too is found in increased numbers in interiors. Some of its many species produce toxic substances that can cause allergic reactions, mucous membrane irritation, headaches, vomiting, and diarrhea.

Aspergillus Penicilloides

Conidia dimensions: 3-3.5 x 4-5 microns. Can grow in areas with low water activity. It is found in house dust and food.

Aspergillus Restrictus

This species is only occasionally pathogenic.


Aw 0.75 – 0.82. Reported to be allergenic. Members of this genus are reported to cause ear infections. Many species produce mycotoxins that may be associated with disease in humans and other animals. Toxin production is dependent on the species or a strain within a species and on the food source for the fungus. Some of these toxins have been found to be carcinogenic in animal species. Several toxins are considered potential human carcinogens. Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms; chronic cases may develop pulmonary emphysema; may also be associated with sinusitis, allergic bronchiopulmonary aspergillosis, and other allergic symptoms.

Aspergillus Sydowi

This species is only occasionally pathogenic.

Aspergillus Terreus

Aw 0.78. Conidia dimensions: 1.8-2.4 microns or 2 – 2.5 microns. Aleurospores 6 – 7 microns in diameter are also produced. Found in warmer soil and in grains, straw, cotton and decomposing vegetation. Can produce the toxin patulin and citrinin that may be associated with disease in humans and other animals. This fungus is associated with aspergillosis of the lungs and or disseminated aspergillosis. Found as an isolate from otomycosis – ear infection, and onychomycosis – infection of finger or toenails.

Aspergillus Ustus

This species is only occasionally pathogenic.

Aspergillus Versicolor

Aw 0.78. Conidia dimensions: 2-3.5 microns. Mostly in temperate zones, it is commonly found in air, house dust, foods (including dairy products), soil, hay, and cotton. It sometimes produces the mycotoxin “sterigmatocystin”, which can cause diarrhea and upset stomach, and is a possible carcinogen, affecting the liver and kidneys. Various other toxins are associated with A. versicolor, such as aspercolorin, averufin, cyclopiazonic acid, and versicolorin. Additionally, the volatile organic compound (VOC) “geosmin” is generated by the action of this mold. Often an irritant to mucus membranes of humans and pets, geosmin has a musty, earthy odor.


Found in soil, forest soils, fresh water, aerial portion of plants, fruit, marine estuary sediments, wood. Allergen, Type I allergies (hay fever, asthma). Type III hypersensitivity pneumonitis: “humidifier fever”, “sauna taker’s lung”. Growth indoors is widespread where moisture accumulates- especially bathrooms and kitchens- on shower curtains, tile grout, windowsills, textiles, liquid waste materials. Potential toxic production is not known. Rare reports of: isolates from skin lesions, keratitis, spleen abscess in a lymphoma patient, blood isolate from a leukemic patient.


Taxonomic designation for fungi of the subdivision “Basidiomycotina”, which includes mushrooms and puffballs. They produce spores that are formed on the outside of a special cell, called the “basidium”.


An exogenous sexual spore (meiospore) borne on a basidium. Or, a spore from a basidiomycete (a member of Basidiomycetes). Many varieties are reported to be allergenic.


A fungus with large spores that could be expected to be deposited in the upper respiratory tract. This fungus can produce the mycotoxin – sterigmatocystin, which has been shown to produce liver and kidney damage when ingested by laboratory animals.


Human pathogen. The fungus is commonly found in soil. It is a dimorphic fungus that has filamentous fungus when grown at 25 degrees C. and a yeast form at 37 degrees C.


Aw 0.93. Conidia dimensions: 7-14 x 5-9 microns. It is parasitic on plants and soft fruits. Found in soil and on house plants and vegetables, it is also known as “gray mold”. It causes leaf rot on grapes, strawberries, lettuce, etc. It is a well-known allergen, producing asthma type symptoms in greenhouse workers and the symptoms of “wine grower’s lung”.


Part of the normal flora of mouth and other mucous membranes in the body. Thrush and other diseases caused by Candida albicans usually occur after prolonged treatment with antibiotics or steroids. The environment is not a likely source of exposure for this fungus. Cells from the organism are usually not airborne. Reported to be allergenic.


See Acremonium


Large ascomycetous fungus producing perithecia. It is found on a variety of substrates containing cellulose, including paper and plant compost. It has been found on paper in sheetrock. It can produce an Acremonium-like state on fungal media. Varieties are considered allergenic and have been associated with peritonitis, cutaneous lesions, and system mycosis.

Cladosporium Fulvum (Fulvia Fulva)

Conidia dimensions: 12-47 x 4-10 microns. It is found on the leaves of tomatoes.

Cladosporium Herbarum

Aw 0.88. Conidia dimensions: 5-23 x 3-8 microns. It is found on dead plants, woody plants, food, straw, soil, paint and textiles.

Cladosporium Macrocarpum

Conidia dimensions: 9-29 x 5-13 microns. It is found on dead plants, woody plants, food, straw, soil, paint, and textiles.

Cladosporium (Hormodendrum)

Aw 0.88; Aw 0.84. Most commonly identified outdoor fungus. The outdoor numbers are reduced in the winter. The numbers are often high in the summer. Often found indoors in numbers less than outdoor numbers. It is a common allergen. Indoor Cladosporium sp. may be different than the species identified outdoors. It is commonly found on the surface of fiberglass duct liners in the interior of supply ducts. A wide variety of plants are food sources for this fungus. It is found on dead plants, woody plants, food, straw, soil, paint, and textiles. Produces greater than 10 antigens. Antigens in commercial extracts are of variable quality and may degrade within weeks of preparation. Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include skin lesions, eye ulceration, mycosis (including onychomycosis, an infection of the nails of the feet or hands) edema and bronchiospasms; chronic cases may develop pulmonary emphysema.

Cladosporium Sphaerospermum

Conidia dimensions: 3-4.5 microns. It is found as a secondary invader of plants, food, soil, paint and textiles.


A thin-walled, asexual spore borne exogenously on an often specialized hypha (conidiophore) and is deciduous at maturity. (plural form: conidia.)

Conidia, Unidentified

These are mold spores that do not show morphological characteristics that allow identification. Because there are tens of thousands of types of fungi, many fall into the “other” or “unknown” category. If they are present in significant numbers, additional measures can be taken to identify them. When spore counts are listed in the category: “Unidentified Conidia” their numbers are considered “normal”.


Can cause a chronic inflammatory disease of the nasal mucosa (entomophthoromycosis).

Cryptococcus Neoformans

A basidiomycetous encapsulated fungal organism found worldwide, mainly around pigeon roosts and soil contaminated with decaying pigeon or chicken droppings. It is generally accepted that the organism enters the host by the respiratory route in the form of a dehydrated haploid yeast or as basidiospores. Hematogenously spreading to extrapulmonary tissues, its predilection for the brain means infected persons usually contract meningoencephalitis, which can be fatal.

Cryptostroma Corticale

Conidia dimensions: 4-6.5 x 3.5-4 microns. Found on the bark of maple and sycamore trees and on stored logs.


Can cause disseminated and pulmonary infections in immune compromised hosts.


Reported to be allergenic and has been associated with allergic fungal sinusitis. It may cause corneal infections, mycetoma, and infections in immune compromised hosts.


A fungal genus of the classification group “Hyphomycetes”. At this time, there is no information available concerning Dictyosporium allergenicity or toxicity, but as a member of the classification group “Dematiaceous Hyphomycetes”, it could potentially cause phaeohyphomycosis (see phaeohyphomycosis). It is found in terrestrial and freshwater habitats, and is a common saprobe of submerged lignocellulose substances. The microscope reveals its spores to be multicellular and tongue-shaped; with subconcentric cells. Colonies may appear dark brown, green-black, or black.


Conidia dimensions: 40-120 x 17-28 microns. Found on grasses, grains and decaying food. It can occasionally cause a corneal infection of the eye.


Conidia dimensions: 15-25 microns. A common allergen. It is found in plants, soil, grains, textiles and paper products.


Can cause infections of skin (including ringworm) and nails.


Neither animals nor plants, these saprophytic and parasitic spore-producing organisms rate a taxonomic kingdom of their own. Fungi include molds, rusts, mildews, smuts, mushrooms, puffballs, and yeasts. It is estimated that more than 1.5 million species of fungi exist.

Fusarium Solani

Aw 0.90. Macroconidia dimensions: 27-52 x 4.4-6.8; Microcondia dimensions: 8-16 x 2-4 microns. Found in plants and soils. Can produce trichothecene toxins that may be associated with disease in humans and animals.


Aw 0.90. A common soil fungus. It is found on a wide range of plants. It is often found in humidifiers. Several species in this genus can produce potent trichothecene toxins. The trichothecene (scirpene) toxin targets the following systems: circulatory, alimentary, skin, and nervous. Produces vomitoxin on grains during unusually damp growing conditions. Symptoms may occur either through ingestion of contaminated grains or possibly inhalation of spores. The genera can produce hemorrhagic syndrome in humans (alimentary toxic aleukia). This is characterized by nausea, vomiting, diarrhea, dermatitis, and extensive internal bleeding. Reported to be allergenic. Frequently involved in eye, skin, and nail infections.


Aw 0.90. Conidia dimensions: 6-12 x 3-6 microns. Aw 0.90. A common contaminant of grains, fruits, dairy products, paper, textiles, soil, and water; often present as part of the normal human flora. The species Geotrichum candidum can cause a secondary infection (geotrichosis) in association with tuberculosis. This rare disease can cause lesions of the skin, bronchi, mouth, lung, and intestine.


A fungus that is structurally similar to Penicillium sp. It is reported to be allergenic.


A mitosporic mold often encountered on decaying plant matter. The genus name prefix “helico” is derived from the shape of the mold’s microscopic structure; certain filaments (sometimes the conidia) curve into a helical path.

Reported effects upon human health in the indoor environment are not available at this time.

Scientists have shown the interaction of Helicomyces roseus with nitrogen-fixing bacteria to be a vital component of an effective soil enriching system (where sugar cane litter is the decomposition target). Helicomyces lilliputeus has long been known as an important sewage treatment systems decomposer, so it is not unexpected that other members of this genus have been observed living on wood submerged in water.


Reported to be allergenic.


A fungus that has filamentous growth at 25 degrees C. and yeast growth at 37 degrees C. It is reported to be a human pathogen. It may be associated with birds.


Grows on products with a high cellulose
content. These fungi are also found in soil and on plant debris.

Hyaline Mycelia

Mycelia that are transparent, translucent, or colorless. If no reproductive structures are present, identification is difficult. Often associated with allergic symptoms.

Hypha (plural form: Hyphae)

One of the tubular, filamentous, branching structures of a fungus (including mold) that develop from germinated spores. A hypha is often divided into sections (of several cells in linear succession) by cross walls called “septa” that usually have perforations through which cytoplasm flows. It is the main means of growth for fungi, and a collective or mass of hyphae is referred to as “mycelium”.


A cellulolytic fungus that is very closely related to Stachybotrys sp. Both fungi have a worldwide distribution and are often found together and are commonly found in soil. Recent studies on mycotoxins revealed that Memnoniella echinata can have a toxicity similar to that of some isolates of Stachybotrys chartarum. Both produce varying amounts of simple trichothecenes. Thus, it is suggested that Memnoniella sp. should also be considered potentially dangerous in indoor air. The major difference between the two fungi is that the conidia of Memnoniella sp. are in long persistent chains while those of Stachybotrys are aggregated in slimy heads. Also the aerodynamic diameter of Memnoniella sp. conidia is smaller and it would be expected to have an even greater potential to penetrate deep into lungs than the conidia of Stachybotrys sp.


Causes ringworm in humans.


Molds are a group of organisms that belong to the taxonomic kingdom of Fungi. There are over 20,000 species of mold. Molds reproduce by making spores. Mold spores waft through the indoor and outdoor air continually. When mold spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on. Molds can grow on virtually any organic substance, as long as moisture and oxygen are present.


Reported to be allergenic. This fungus produces soft rot of tree fruits. Other members produce a red bread mold. It is infrequently involved in corneal eye infections.


Often found in soil, dead plant material, horse dung, fruits and fruit juice. It is also found in leather, meat, dairy products, animal hair, and jute. A Zygomycetes fungus that may be allergenic (skin and bronchial tests). This organism and other Zygomycetes will grow rapidly on most fungal media. May cause mucorosis in immune compromised individuals. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites.

Mycelium (plural form: mycelia)

A mass of interwoven hyphae (a hypha is a filamentous part of a fungus that usually has several cells in linear succession with dividing walls in between) that is often submerged in soil or organic matter or the tissues of a host.


A taxonomic designation for fungi that are included in the category of “slime molds”. They’re occasionally found indoors, but mainly reside in forested regions on decaying logs, stumps, and dead leaves. Myxomycetes display characteristics of fungi and protozoans. In favorable (wet) conditions they exhibit motile, amoeba-like cells, usually bounded only by a plasma membrane, that are variable in size and form. During dry spells, they form a resting body (sclerotium) with dry, airborne spores. These fungi are not known to produce toxins, but can cause hay fever and asthma.


Commonly found in warm climates, this mold may be responsible for allergic reactions such as hay fever and asthma. It is found on decaying plant material and in the soil. It is not often found indoors.


The asexual phase of Erysiphe sp. It is a plant pathogen causing powdery mildews. It is very common on the leaves stems, and flowers of plants. The health effects and allergenicity have not been studied. It does not grow on non-living surfaces such as wood or drywall.


Commonly found in soil and dust; less frequently in air. P. variotii can cause paecilomycosis. Linked to wood-trimmer’s disease and humidifier associated illnesses. They are reported to allergenic. Some members of this genus are reported to cause pneumonia. It may produce arsine gas if growing on arsenic substrate. This can occur on wallpapers covered with Paris green.


These fungi are found in soil, textiles, decaying plants, manure, and paper.


Aw 0.78 – 0.88. A wide number of organisms have been placed in this genus. Identification to species is difficult. Often found in aerosol samples. Commonly found in soil, food, cellulose and grains. It is also found in paint and compost piles. It may cause hypersensitivity pneumonitis, allergic alveolitis in susceptible individuals. It is reported to be allergenic (skin). It is commonly found in carpet, wallpaper, and in interior fiberglass duct insulation. Some species can produce mycotoxins. Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms; chronic cases may develop pulmonary emphysema. It may also cause headaches, vomiting, and diarrhea.


Found in soil, blackened and dead herbaceous stems, leaf spots, grasses, rushes, and sedges. Almost always associated with other fungi. Rarely found growing indoors. Reportedly associated with a rare case of mycotic keratitis.


A fruiting body of a fungus in which some types of spores (including ascospores) are produced. (plural form: Perithecia)


These species are plant pathogens and the genus is one that causes downy mildews. Peronospora is very common and is an obligate parasite (obligate parasites cannot grow on non living environmental surfaces) found on leaves, stems, flowers, and fruits of living higher plants. Peronospora sp. may be identified in air on spore trap samples since spores have a distinctive morphology. The spores may also be seen in dust as part of the normal influx of outdoor microbial particles. As of this writing, allergenicity has not been studied and no information is available regarding health effects or toxicity.


A hyphomycosis (infection by a mold of the taxonomic designation “Hyphomycetes”) in which the infiltrating microbes are usually of the mold family “Dematiaceae”, and are characterized by the coloring of their mycelium; the prefix “phaeo” means “dusky-brown”. Various forms of the disease involve different areas of the body, such as the skin or respiratory tract. Intrusion of the mold in the eye, brain, bone, or subcutaneous tissue typically occurs as a result of trauma to the affected area.


A common indoor air allergen that can cause hay fever, asthma, and a type of hypersensitivity pneumonitis commonly called “shower curtain disease” (shower surfaces being among those frequented by this fungal organism). Phoma infections in humans also have been reported; usually affecting the immunocompromised, they include mycotic keratitis (fungal infection of the cornea), skin infections, and phaeohyphomycosis (see phaeohyphomycosis).

For a positive identification of this genus, the specimen must contain the pycnidia (a round to pear-shaped fruiting structure containing conidia) to confirm the presence of simple phialides (a cell from which conidia are extruded). A cultured sample would provide these components. Colonies are rapid growing, appear powdery to velvety, and exhibit many different colors. This mold is known to grow on butter, rice, potatoes, paint (sometimes seen as pink and purple spots on painted walls), cement, rubber, wood, paper, and under linoleum. In nature, the species are found in soil, manure, on fruit, dead plants, and as parasites on live plants.

Researchers have discovered that when Phoma macrostoma is sprinkled onto the soil in areas with no preexisting weeds, it acts as an earth-friendly herbicide, inhibiting the ability of many broadleaf plants (including dandelions) to produce chlorophyll; the young broadleaf plants turn white and die while grass seems to be unaffected.


A native of mostly tropical environments, it commonly grows on dead plants, soil, wood, and especially the dead leaves and grasses of livestock fodder. Pithomyces chartarum produces sporidesmin (a piperazinedione), a mycotoxin known to cause animal liver damage, and it causes facial eczema in cattle, sheep, and goats. For humans, it is considered a possible allergen, and a potential infectious agent in immunocompromised patients.

Not known to be prolific indoors, this mold can sometimes be found on paper. It exhibits distinctive multi-celled brown conidia.


The Zygomycetous fungus is reported to be allergenic. It may cause mucorosis in immune compromised individuals. It occupies a biological niche similar to Mucor sp. It is often linked to occupational allergy. May cause mucorosis in immune compromised individuals. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites.


The Zygomycetous fungus is reported to be allergenic. It may cause mucorosis in immune compromised individuals. It occupies a biological niche similar to Mucor sp. It is often linked to occupational allergy. May cause mucorosis in immune compromised individuals. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites.


A reddish yeast typically found in moist environments such as carpeting, cooling coils, and drain pans. In some countries it is the most common yeast genus identified in indoor air. This yeast has been reported to be allergenic. Positive skin tests have been reported. It has colonized terminally ill patients.

Rusts (and Smuts)

These fungi are associated with plant diseases. In the classification scheme of the fungi, the smuts have much in common with the rusts, and they are frequently discussed together. Both groups produce wind-borne, resistant teliospores that serve as the basis for their classification and their means of spread. Rusts usually attack vegetative regions (i.e., leaves and stems) of plants; smuts usually are associated with the reproductive structures (seeds). They can cause hay fever and asthma.


Reported to be allergenic. Baker’s yeast.


It may produce arsine gas if growing on arsenic substrate. This can occur on wallpapers covered with Paris green. It has been found growing on a wide variety of materials including house dust. It is associated with type III allergy.


Most easily recognized by the spores, which are colorless to yellow, spiny, round, 1-celled, and produced singly at the ends of short filaments. Sometimes phialides of the Acremonium or Gabarnaudia type may also occur. A few species of Mortierella, as well as the human pathogen Histoplasma capsulatum, produce spores resembling those of Sepedonium. Isolated from soil, but most commonly parasitized mushrooms.

Serpula Lacrymans

Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms; chronic cases may develop pulmonary emphysema.


See rusts.


This mitosporic fungus (spores develop by means of asexual cell division) is included in the classification group “Hyphomycetes”. At this time, no information is available concerning Spegazzinia allergenicity or toxicity. Spegazzinia spores can be identified in air samples by their distinctive structure, and have the potential to produce a colony within seven to ten days. Colonies are considered relatively slow growing, and are brownish-black to black in color. This saprobe (deriving its nourishment from nonliving or decaying organic matter) is most commonly found in warm-temperate to tropical areas in soil and on dead leaves, stems, trees, and other various kinds of plant debris.


The means by which molds reproduce. Spores are microscopic (2-100 micrometers) and various shapes. Distribution can be accomplished by a breeze, water droplet, or a person or animal passing by. They can even be discharged by the mold (usually under moist conditions or high humidity).


Reported to be allergenic.


A mitosporic fungal genus of the classification group “Hyphomycetes”. At this time, no information is available concerning Sporoschisma allergenicity or toxicity. It is known to exist on wood and stems, and these can be submerged in fresh water. Microscopic features include quadriseptate spores, originating in an enclosed membrane.


The species Sporothrix schenckii can cause sporotrichosis, but usually only in individuals that are immune compromised. Sporotrichosis is a chronic fungal infection that results when the mold enters the body where the skin is damaged or via the lungs. If it reaches the bloodstream, it can affect many other parts of the body.


Reported to be allergenic. Additionally, Sporotrichum pruinosum has been observed in the respiratory secretions of some human patients, indicating a possible ability to colonize the bronchopulmonary pathways. This genus does not cause sporotrichosis (see also Sporothrix, for there is some taxonomic confusion between these two genera).

Rarely found in cooler regions, Sporotrichum is prevalent in warm-temperate and tropical zones, and grows (rapidly) on soils, decaying plant matter, wet or rotting wood, grasses, and landscaping mulch. Colonies may appear white, rosy-beige, or orange, and have a velvety to granular texture.


Aw – 0.94 , optimum Aw ->0.98. Several strains of this mold (S. atra, S. chartarum, and S. alternans are synonymous) may produce macrocyclic trichothecenes (one of which is Satratoxin H) that are poisonous by inhalation. These mycotoxins, when present, are primarily associated with the mold’s spores.

Individuals with chronic exposure to Stachybotrys’s toxins reported cold and flu symptoms, sore throats, diarrhea, headaches, fatigue, dermatitis, hair loss, general malaise, and psychological depression. For infants, the toxins create a vulnerability to a serious condition called pulmonary hemosiderosis (bleeding in the lungs) where severe bleeding can result in coughing blood or nosebleeds, and low grade bleeding can cause chronic coughs and congestion with anemia. People who unknowingly handled material contaminated with this mold described symptoms of cough, rhinitis, burning sensations of the mouth and nasal passages, and cutaneous irritation at the point of contact, especially in areas of abundant perspiration. The toxins produced by this mold will suppress the immune system, affecting the lymphoid tissue and the bone marrow. Animals injected with macrocyclic trichothecenes exhibited the following symptoms: necrosis and hemorrhage within the brain, thymus, spleen, intestines, lung, heart, lymph nodes, liver, and kidneys.

This is a dark-colored fungus that grows on building materials with a high cellulose content and a low nitrogen content. It is slow growing when compared to other common molds, and may not appear to compete well in their presence. Yet, when moisture levels are high for prolonged periods, Stachybotrys may gradually become the dominating genus (possibly because of its yield of mycotoxins, which are believed to be directed against other molds and bacteria). This organism is usually difficult to find in indoor air samples unless it is physically disturbed, but when it does appear it is an alert to find the source, as it will likely be found growing in abundance. Its spores–which can be found in a gelatinous mass–will die readily after release, but are still allergenic and can be toxigenic. Areas with a relative humidity above 55%, and are subject to temperature fluctuations, are ideal for toxin production.


This genus is included in the taxonomic designation “Hyphomycetes”. It is a known allergen, causing Type I allergies (examples: hay fever, asthma). Phaeohyphomycotic sinusitis has been reported in connection with this mold. (See phaeohyphomycosis.)

Existing mainly in the temperate northern hemisphere, it can be found in soil, moist wood or cellulose materials, on decomposing plants, and as pathogens on living plants (leaf spots are one example). Colonies grow rapidly, and appear velvety to cottony in texture; coloring is light brown or olive green to black. Though it is rare to find indoor colonization, it has been found in dust that is transferred in from outside, including dust on air filters.


Can cause a respiratory infection characterized by a solid intracaitary fungal ball.


(Phonetic Pronunciation: Tay-knee-ol’-el-luh) This genus of the classification group “Dematiaceous Hyphomycetes” has been isolated from human cutaneous and subcutaneous lesions, making it a possible etiological agent of phaeohyphomycosis (see phaeohyphomycosis). Studies of its allergenicity and toxicity are not known at this time. Taeniolella lacks a known sexual state (placing it in the “Fungi Imperfecti” category) and is known to reproduce asexually by the process of mitosis. In temperate North America, this weak saprobe’s natural habitat commonly includes dead branches, wood, and senescent leaves. Indoors, they are sometimes found on lumber, other forms of wood, and plants. Taeniolella may be identified from tape lift, bulk, or airborne spore samples.


Found outdoors in air, soil, on dead vegetation, wood, and grasses. Also found indoors on cellulosic materials. Reported to be allergenic and may cause hay fever and asthma.


This is a widespread mitosporic (lacking a sexual state) fungus of the classification group “Hyphomycetes”. There is little information regarding toxicity or allergenicity, but it is known to rarely be the causative agent for human keratitis (infection of the cornea).

Various species of this genus may be identified from indoor sampling (one species in particular, Trichocladium uniseptatum, is found regularly on indoor environmental surfaces, especially wood). Outdoors, it is found on dead wood, stems or twigs, tubers of various plants, pine needles, other plant debris, and in soils. It is notable that this microbe has been associated with black root rot, as an aggressive plant pathogen.


It is commonly found in soil, dead trees, pine needles, paper, and unglazed ceramics. It often will grow on other fungi. It produces antibiotics that are toxic to humans. It has been reported to be allergenic. It readily degrades cellulose.


Can cause ringworm, athlete’s foot, jock itch, and other infections of the skin, nail, beard and scalp. Reported to be allergenic. Found on soil and skin.


Aw 0.90. Conidia dimensions: 12-23 x 8-10 microns. Found in decomposing vegetation, soil, corn seeds, and in flour. The species Trichothecium roseum can produce a trichothecene toxin that may be associated with disease in humans and other animals. Reported to be allergenic.


Reported to be allergenic.


Aw 0.89. This mold is reported to be a major allergen, capable of causing hay fever and asthma. It is also known to rarely cause subcutaneous infections. The University of Adelaide, Australia, categorizes this microbe in the classification group “Dematiaceous Hyphomycetes”, which includes it as a possible causative agent of phaeohyphomycosis (see phaeohyphomycosis).

Widely distributed in nature and considered a saprobe (weak parasite), some of its growth sites are soil, grasses, dead or dying plants (mainly herbaceous vegetation), manure, and compost. In interior environments it has been found on paper, painted surfaces, gypsum board, textiles, jute, straw materials, carpets, cellulose building materials (including wood), and in dust and air samples. Colonies are moderately fast growing, usually appearing olive-brown (or rusty-brown) to black (or grayish), with a texture that is granular to velvety.


Conidia dimensions: 2.3-10 x 1-2.6 microns. Found in decaying vegetation, on straw, soil and arthropods. A rare cause of corneal infections.
Aw 0.75. Conidia dimensions: 2.5-3.5 microns. Found in sugary foods, salted meats, dairy products, textiles, soil, hay and fruits.


Various yeasts are commonly identified on air samples. Some yeasts are reported to be allergenic. They may cause problems if a person has had previous exposure and developed a hypersensitivity. Yeasts may be allergenic to susceptible individuals when present in sufficient concentrations.

“Aw” refers to the water activity measurement, where Aw is equal to the relative humidity of the air surrounding the sample when the air and the sample are at equilibrium (in an enclosed space).

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