Absidia sp. – Allergenic. A zygomycete fungus which is considered common to the indoor environment. May cause mucormycosis in immune compromised individuals. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites. Absidia conidia have been an invasive infection agent in AIDS and neutropenic patients, as well as, agents of bovine mycotic abortions, and feline subcutaneous abscesses.

Acremonium sp. (Cephalosporium sp.) – Allergenic and toxic. Can produce a trichothecene toxin, which is toxic if ingested. It was the primary fungus identified in at least two houses where the occupant complaints were nausea, vomiting, and diarrhea. It can produce mycetomas, infections of the nails, onychomycosis, corneal ulcers, eumycotic mycetoma, endophthalmitis, meningitis, and endocarditis.

Alternaria sp. – Allergenic. Commonly found in outdoor air, on many kinds of plants and food products and prefers rotting farmland manure. It may be resistant to fungicides. Alternaria is considered an occasional contaminant of water damaged building materials which contain cellulose. Although Alternaria is a notable source of fungal allergy, pathogenic infections are also reported infrequently.

Arthrographis spp. – Should be considered allergenic. A species of Arthrographis, A. kalrae, has been documented in onychomycosis and has been recovered from the skin, nails, and respiratory sites but has not been established as an etiological agent. No toxic related diseases are of record to date.

Aspergillus sp. – Allergenic, pathogenic, and toxic. A genus of fungi containing approximately 150 recognized species. All of the species contained in this genus should be considered allergenic. Various Aspergillus species are a common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchospasms. Chronic cases may develop pulmonary emphysema. Members of this genus are reported to cause a variety of opportunistic infections of the ears and eyes. Severe pulmonary infections may also occur. Many species produce mycotoxins, which 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.

Aspergillus clavatus – Allergenic. This distinctive species is a common soil fungus with widespread distribution in soils in warmer climates. Not common in indoor environments, but is quite widely distributed in some kinds of foods, especially cereals, and it has been frequently associated with the brewing industry. No toxic or invasive diseases have been documented to date.

Aspergillus flavus – Allergenic, pathogenic, and toxic. This species may be recovered from the indoor environment; it has been reported in water damaged carpets. Its presence has been associated with reports of asthma. Approximately 50% of the 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 also a human carcinogen. The production of the fungal toxin is dependent on the growth conditions and on the substrate used as a food source. The toxin is poisonous to humans by ingestion and may directly affect the liver. Experiments have indicated that it is teratogenic and mutagenic. This fungus may also result in disease via inhalation and is associated with aspergillosis of the lungs and/or disseminated aspergillosis. This fungus is occasionally identified as the cause of corneal, otomycotic, and infections in the nasal cavity.

Aspergillus fumigatus – Allergenic and pathogenic. This species may be recovered from the indoor environment. Considered as a principle cause for both invasive and allergic aspergillosis. This organism will particularly affect individuals who are immune compromised. It is considered a true human pathogen. No toxic diseases have been documented to date.

Aspergillus glaucus – Allergenic and pathogenic. This species may be recovered from the indoor environment. It has been reported as a common outdoor fungus in the winter. This species is only occasionally pathogenic and has been associated with sinusitis, otitis, cerebral, orofacial, and pulmonary infections. No toxic diseases have been documented to date.

Aspergillus nidulans – Allergenic and toxic. This species is not considered common to indoor environments. This species has been reported in a variety of animal and human infections including invasive and systemic disease including aspergillosis of the lungs and/or disseminated aspergillosis. It can produce the mycotoxin sterigmatocysti that has been shown to produce liver and kidney damage in lab animals. 

Aspergillus niger – Allergenic. This species is considered common to indoor environments. It is common in secondary organisms following bacterial otitis and is more commonly being implicated in pulmonary disease in immune compromised hosts. It has also been reported to cause skin infections.

Aspergillus terreus – Toxic. Found in patients with cystic fibrosis, this species has grown in the human ear causing otomycosis and can damage human nails (onychomycosis) and skin. It can produce a variety of mycotoxins, including itaconic acid, patulin, mevinolin, and citrinin, which may be associated with disease in humans and animals.

Aureobasidium sp. – Allergenic. This species has been associated with dermatitis, peritonitis, pulmonary infection, and invasive disease in AIDS patients. Probably acquired by traumatic implantation. May be recovered as a contaminant from human cutaneous sites. No toxic diseases have been documented to date. Commonly considered a contaminant.

Beauveria – Allergenic. Not considered to be common to indoor environments. Reported to cause mycotic keratitis and occasional pulmonary infections. No toxic diseases have been documented to date.

Bipolaris sp. – Toxic. Common to both indoor and outdoor environments. Older obsolete names include Drechslera and Helminthosporium. This fungus produces large spores, which would be expected to be deposited in the upper respiratory tract. Various species of this fungus can produce the mycotoxin—sterigmatocystin—that has been shown to produce liver and kidney damage when ingested by laboratory animals.

Botrytis sp. – Allergenic. No toxic or invasive diseases have been documented to date. Commonly considered a contaminant.

Cephalosporium sp. – See Acremonium sp.

Chaetomium sp. – Commonly considered a contaminant, but are also encountered as causative agents of infections in humans.

Chrysosporium spp. – Common outdoor mold. Rare agents of onychomycosis, skin lesions, endocarditis, and uncommon agents of the pulmonary mycosis adiaspiromycosis. No toxic diseases have been documented to date.

Cladosporium sp. (Hormodendrum sp.) – Allergenic. Most commonly identified outdoor fungus. It can cause mycosis. 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 edema and bronchospasms; chronic cases may develop pulmonary emphysema.

Cunninghamella sp. – Can cause disseminated and pulmonary infections in immune compromised hosts.

Curvularia sp. – Allergenic. It may cause corneal infections, mycetoma and infections in immune compromised hosts.

Drechslera sp. – See Bipolaris sp.

Epicoccum sp. – Allergenic. Commonly known as a contaminant. No toxic or invasive diseases documented to date.

Exophiala sp. – Causes the superficial dematiaceous infection, tinea nigra as well as keratomycosis and phaeohyphomycosis. Some species cause infections of the brain and eye as well as cutaneous and subcutaneous tissue.

Exserohilum sp. – Causes phaeohyphomycosis, most commonly in the nasal sinuses, subcutaneous tissue and cornea. Fatal dissemination infections have been reported but are rare.

Fonsecaea sp. – Commonly causes chromoblastomycosis (skin lesions). Rarely causes internal infections.

Fusarium sp. – Allergenic and toxic. A common soil fungus. 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. It is also frequently involved in eye, skin and nail infections.

Geotrichum sp. – 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.

Gliocladium sp. – Allergenic. Commonly considered a contaminant. No toxic diseases caused to date.

Graphium sp. – May be found as a contaminant. This genus is commonly considered non-pathogenic but may occasionally cause disease in severely immune compromised patients.

Malbranchea sp. – has been isolated from a case with sinusitis. No other infection associated with Malbranchea has been reported so far.

Microsporum sp. – Causes ringworm and other skin infections in humans. Usually does not invade living tissue, rather it colonizes the outermost layer. No toxic or invasive diseases documented to date.

Monilia sp. – Allergenic. Commonly considered a contaminant. This fungus produces soft rot of tree fruits. Other members produce a red bread mold. It is infrequently involved in corneal eye infections.

Mucor sp. – 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.

Nigrospora sp. – Allergenic. Commonly considered a contaminant. Involvement in disease has been very rarely reported.

Non-sporulating Fungi – Allergenic. Commonly considered a contaminant. This genus is commonly considered non-pathogenic. Often associated with allergic symptoms. Other common names include Hyaline mycelia and mycelia sterilia.

Paecilomyces sp. – Allergenic. The species P. variotii can cause paecilomycosis. Linked to wood-trimmers disease and humidifier associated illnesses. Some members of this genus are reported to cause pneumonia. It may produce arsine gas if growing on arsenic substrate, i.e. wallpapers covered with paris green.

Penicillium sp. – Allergenic and toxic. A wide number of organisms have placed in this genera. 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 and allergic alveolitis in susceptible individuals. Some species can produce mycotoxins. Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchospasms; chronic cases may develop pulmonary emphysema.

Phoma sp. – Allergenic. It may have antigens, which cross-react with those of Alternaria sp. It may cause phaeohyphomycosis, a systematic or subcutaneous disease.

Pithomyces sp. – Commonly considered a contaminant and, very rarely, has been implicated as an etiological agent in immune compromised hosts. Causes facial eczema in ruminants.

Rhizomucor sp. – Allergenic. It may cause mucormycosis in immune compromised individuals. It is often linked to occupational allergy. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites.

Rhizopus sp. – Allergenic. It may cause mucormycosis in immune compromised individuals. It is often linked to occupational allergy. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple sites.

Rhodotorula sp. – Allergenic. Positive skin tests have been reported. It has colonized in terminally ill patients.

Scopulariopsis sp. – Allergenic. 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.

Scytalidium sp. – Known to commonly cause nail and skin infections; there are also rare reports of more deep-seated infections, e.g., subcutaneous abscesses, sinusitis, endophthalmitis, lymphadenitis and fungemia in immune compromised patients.

Sepedonium sp. – Commonly considered a contaminant. This genus is commonly considered non-pathogenic.

Sporothrix sp. – Can cause sporotrichosis, however this usually only occurs in populations which are immune compromised.

Sporotrichum sp. – Allergenic. Commonly considered a contaminant. Has been found in sputa from patients with chronic respiratory disorders, but the significance is unclear.

Stachybotrys sp. – Toxic. Several strains of this fungus (S. atra, S. chartarum and S. alternans are synonymous) may produce a trichothecene mycotoxin- Satratoxin H - which is poisonous by inhalation. The toxins are present on the fungal spores. This is a slow growing fungus on media. It does not compete well with other rapidly growing fungi. The dark colored fungi grows on building material with a high cellulose content and a low nitrogen content. Areas with relative humidity above 55% and are subject to temperature fluctuations are ideal for toxin production. Individuals with chronic exposure to the toxin produced by this fungus reported cold and flu symptoms, sore throats, diarrhea, headaches, fatigue, dermatitis, intermittent local hair loss, and generalized malaise. The toxins produced by this fungus will suppress the immune system affecting the lymphoid tissue and the bone marrow. Animals injected with the toxin from this fungus exhibited the following symptoms: necrosis and hemorrhage within the brain, thymus, spleen, intestine, lung, heart, lymph node, liver, and kidney. The mycotoxin is also reported to be a liver and kidney carcinogen. Affects by absorption of the toxin in the human lung are known as pneumomycosis. This organism is rarely found in outdoor samples. It is usually difficult to find in indoor air samples unless it is physically disturbed. The spores are in a gelatinous mass. The spores will die readily after release. The dead spores are still allergenic and toxigenic. Percutaneous absorption has caused mild symptoms.

Stemphylium sp. – Allergenic. Commonly considered a contaminant. No toxic or invasive diseases documented to date.

Syncephalastrum sp. – Commonly considered a contaminant. Can cause a respiratory infection characterized by a solid fungal ball.

Trichoderma sp. – Allergenic and toxic. Commonly considered a contaminant. Occasional reports of infection in immune compromised patients. Several cases of peritonitis have been reported in patients undergoing peritoneal dialysis. It produces antibiotics, which are toxic to humans.

Trichophyton sp. – Allergenic. Can cause ring worm, athlete's foot, skin, nail, beard, and scalp. Found on soil and skin.

Trichosporon spp. – A part of the normal flora of mouth, skin and nails, it is the causative agent of superficial and deep infections in humans.

Ulocladium sp. – Commonly considered a contaminant. It is widely distributed in nature, especially the soil and decaying plants, and may be isolated from paper, wood, and textiles. May rarely cause human disease, including phaeohyphomycosis and particularly subcutaneous infections.

Ustilago sp. – Seldom implicated in human disease, but may be inhaled and subsequently isolated from sputum specimens.

Verticillium sp. – Commonly known as a contaminant. Rarely causes inflammation of the cornea.

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