Genus

Outdoor origin

Indoor mold growth

Potential Health Effects

Acremonium

(c)

Soil, dead organic debris, hay, foodstuffs.

Requires very wet conditions.

Allergic: Type I allergies (hay fever, asthma). Type III hypersensitivity pneumonitis; Humidifier lung.

Alternaria

(a)

Common mold in outdoor air.  Found in soils, seeds and plants. Reaches peak in late summer.

Often found in carpets, textiles, house dust, window frames or where there is condensation; damp spots around showers and on horizontal surfaces in building interiors.

Allergic: Common cause of an allergic response, asthma. Large spore; deposits in nose, mouth and upper respiratory tract; may be related to Baker’s asthma.

Toxic: Alternaria alternata is capable of producing tenuazonic acid and other toxic metabolites, which may be associated with disease in humans or animals.

Arthrinium

(c)

Soil, decaying plants.

Grows on cellulose but is rarely found.

Allergic: One species reported as allergen.

Toxic: Not known

Ascospores

(c)

Plant pathogens everywhere in nature.  Increase after rain or high humidity.

Chaetomium is an Ascospore often found indoors on cellulose-based substrates.

Allergic: Many types. Some are allergenic.

Toxic: Many produce toxins, depending on genus and species.

Aspergillus

(a, c)

Found in compost heaps, dead vegetation, cereal grains, soil, plant debris.

Commonly isolated from house dust. Found in water -damaged carpets, building materials, and damp areas.

Allergic: Common allergen. May cause allergies, hay fever, asthma; hypersensitivity pneumonitis, allergic broncho-pulmonary aspergillosis (ABPA), allergic fungal sinusitis, invasive aspergillosis.

Toxic: Many are capable of producing toxins under correct conditions.

Aureobasidium (c, f)

Frequently found in the soil; worldwide distribution. Colonizes leaves.

Common sources are kitchen, bathrooms, poorly maintained HVAC systems, areas exposed to elevated moisture or humidity.

Allergic: Common allergen. May cause allergies, hay fever, asthma. Can cause hypersensitivity pneumonitis; Humidifier fever.

Toxic: No known toxins.  Infections rare.

Basidiospores  [mushrooms]

(a)

Saprophytes and plant pathogens. Gardens, forests, woodlands.

The agent of "dry rot” causes white and brown wood rot; grow and destroy the structural wood of buildings.

Allergic: Many species reported to be allergenic (hay fever, asthma). May induce hypersensitivity pneumonitis.

Toxic: Some are toxic if ingested.

Botrytis

(a, b)

Cause vegetable and ornamental plant diseases.

May be found in conjunction with indoor plants.

Allergic: Common allergen. May cause allergies, hay fever, and asthma; hypersensitivity pneumonitis; Winegrower's lung.

Bacteria

Not fungi but found where fungi occur

Cause unpleasant odors; gram negative bacilli have endotoxins.

Chaetomium

(a)

Soil, seeds, cellulose substrates, dung, woody and straw materials.

Found on substrates containing cellulose, including paper, sheetrock and plant compost.

Allergic: Reported to be allergenic (hay fever, asthma). Not well studied.

Toxic: Produces a toxin that inhibits cell division.

Cladosporium

(a, b)

Most commonly identified outdoor fungus.  Found on dead plants, woody plants, food straw, soil, paint and textiles.

Indoor species may be different than the species identified outdoors. Grows on textile, wood, moist windowsills.

Allergic: Common and important allergen (hay fever, asthma). Can cause hypersensitivity pneumonitis.

Toxic: May produce toxins-- Cladosporin or emodin, neither of which is highly toxic.

Curvularia

(a, c)

Plant debris, soil; plant pathogen.

Grows on a variety of materials.

Allergic: Common allergen. Can cause sinusitis.

Toxic: Not known.

Drechslera, Bipolaris, and Exserohilum group (c)

Plant pathogen, particularly grass.  Soil, plant debris.

On a variety of materials.

Allergic: Common allergen (hayfever, asthma). Most reported cause of allergic sinusitis.

Toxic: Not known.

Epicoccum sp. (a)

Found in plants, soil, and grains. Very common on dead or dying plants.

Found in textiles and paper products.

Allergic: A common allergen.

Fusarium

(a)

Common soil fungus, found on a wide range of plants.

Often found in humidifiers.  Fusarium requires very wet conditions.

Allergic: Reported to be allergenic. Type I allergies (hay fever, asthma).

Toxic: Several species can produce potent trichothecene toxins targeting the circulatory, alimentary, skin and nervous systems.  Produces vomitoxin.

Memnoniella

(c)

Plant litter, soil, many types of plants and trees.

On a variety of substrates. Very closely related to Stachybotrys. Cellulolytic.

Allergic: Allergenicity not studied.

 Toxic: Can produce trichothecenes similar to Stachybotrys toxins and griseofulvins.

Mucor

(c, g)

Found in hay, stored seeds, horse manure and house dust. 

Frequently found in air samples from indoor environments. Accumulated dust in HVAC systems.

Allergic: Heavy exposure can cause extrinsic allergic alveolitis, type II (IgG) response.

Mycelia, Mycelial fragments

Filamentous, vegetative part of the fungus. The spores, which are the reproductive parts, emerge from the mycelia or hyphae. Differentiation of mycelia into a genus is not possible.

Allergic: Have been associated with allergic symptoms.

Toxic: Spores have the highest concentrations of toxins but the mycelia also contain them. (d)

Myxomycetes

(c)

Decaying wood, dead leaves.

Occasionally found indoors.

Allergic: Type I allergies (hay fever, asthma).

Nigrospora

(c)

Decomposing plant material and soil.

Growth indoors is rare.

Allergic:  Type I allergies (hay fever, asthma).

Paecilomyces

(c)

Commonly found among dead plants and compost.  Decomposes food.

Jute fibers, paper, PVC, timber (oak) cigar tobacco, harvested grapes, bottled fruit, and fruit juice undergoing pasteurization.

Allergic: Type I allergies (hay fever, asthma). Type III hypersensitivity pneumonitis: Humidifier lung.

Toxic: Paecilotoxins, byssochlamic acid, variotin, ferrirubin, viriditoxin, indole-C-acetic acid, fusignen and patulin.

Penicillium

(c)

Commonly found in soil, food and grains.

Grows in water-damaged buildings on wallpaper, wallpaper glue, decaying fabrics, moist chipboards.

Allergic: Common allergen. May cause allergies, hay fever, asthma; can induce hypersensitivity pneumonitis.

Toxic: Various toxins by different species. Some species produce toxins that render food inedible or dangerous.

Periconia

(b)

Parasitic or saprophytic on plant material.

Rarely found growing indoors.

Allergic: Not studied.

Toxic: None known.

Pithomyces

(c)

Growing on decaying plants, grasses.

Rarely found growing indoors. Can grow on paper.

Allergic: Not studied.

Toxic: Sporidesmin.

Rhizopus

Common on decaying fruits and vegetables, animal dung and compost.

House dust, spoiling food.

Allergic: Causes allergies (hay fever, asthma); hypersensitivity pneumonitis:
"Sawmill lung" (an extrinsic allergic alveolitis).

Rust, Smut

Plant parasites that are host- specific for grass, flowers, trees and living plants.

Rusts or smuts do not grow indoors unless host plants are present.  

Allergic: Type I allergies (hay fever, asthma).

Scopulariopsis (a)

Occurring in soil, dung, decaying plant debris, and house dust.

Allergic: Causes hayfever and asthma.

Toxic: May produce arsine gas if growing on arsenic substrate, such as wallpapers covered with Paris green.

Stachybotrys

(a)

Soil, decaying plant substrates, decomposing cellulose (hay, straw), leaf litter, and seeds.

Grows on building material high in cellulose and low nitrogen content, such as paper wallboard, jute, wicker, straw & baskets.

Allergic: Not well studied. Type I allergies reported.  Toxic: May produce potent trichothecene mycotoxins such as Satratoxin H.  Chronic exposure to the toxin reported to cause cold/ flu symptoms, sore throats diarrhea, headaches, fatigue, dermatitis, intermittent hair loss and malaise. Toxins suppress immune system.

Stemphylium

(b)

Occurring on decaying and living plants and in soil.

Commonly found on cellulose material such as cotton cloth, ceiling tiles, paper.  Requires wet conditions.

Allergic: Known allergen. Shares allergens with Alternaria. Type I allergies (hay fever, asthma).

Taeniolella

(c)

Grows in leaves and on wood.

On wood and plants.

Allergic: Not studied.

Toxic: Not studied.

Torula

(c)

Soil, wood, grasses

Found indoors on cellulose-based materials such as jute, wicker, baskets, wood, and paper.

Allergic: Type I allergies (hay fever, asthma).

Trichoderma

(c, e)

Widely spread in soil; colonizes dead leaves, fallen timber, compost heaps activated sludge.

Readily degrades cellulose and often found in water or moisture damaged buildings, paper, textiles.

Allergic: May cause allergies, hay fever, and asthma; can induce hypersensitivity pneumonitis.

Toxic: Trichodermin and trichotoxin A, toxins closely related to the Stachybotrys trichothecenes.

Ulocladium

(c)

Soil, dung, paint, grasses, fibers, wood, decaying plant material, paper, and textiles.

Widespread. Found on gypsum board, paper, paint, jute tapestries, other straw materials. Needs high water content.

Allergic:  Type I allergies (hay fever, asthma).

Yeast