- May 23, 2023
This glossary provides a list of spore commonly found in the California region. It is intended to provide general information about commonly occurring molds, and is not intended to be a complete source.
Molds come in all shapes and sizes which make some more difficult to eliminate than others.
Please visit the following url for more information on spore types:
Distribution: Alternaria is one of the most common molds and is abundant worldwide. This genus contains around 40 to 50 different species, only a few of which are commonly found indoors.
How it is spread: Alternaria spores are easily dispersed through the air by wind.
Where it is found outdoors: Alternaria is common outdoors in soil, dead organic debris, foodstuffs, and textiles. It is also a plant pathogen and is frequently found on dead or weakened plants.
Where it is found indoors: Alternaria can grow on a variety of substrates indoors when moisture is present.
Distribution: Acremonium is a common mold, including about 80 to 90 different species.
How it is spread: Acremonium produces wet slimy spores and is normally dispersed through water flow or droplets, or by insects. Old dry Acremonium spores can sometimes be dispersed through the air by wind.
Where it is found outdoors: Acremonium is found in soil, on dead organic material and debris, hay, and foodstuffs.
Where it is found indoors: Acremonium can be found anywhere indoors, but requires very wet conditions in order to proliferate. The spores probably require active disturbance for release.
Aspergillus: (see Penicillium/Aspergillus)
Distribution: Basidiospores are produced by a very large and diverse group of fungi called basidiomycetes, which contains over 1000 different genera. This group includes many well-known macro fungi, such as mushrooms. Basidiospores are often abundant in outdoor air and sometimes in indoor air.
How they are spread: Many types of basidiospores are actively released into the air during periods of high humidity or rain. Once the spores are expelled into the air, they are dispersed easily by wind.
Where they are found outdoors: Basidiomycetes are very common outdoors and can be found in gardens, forests, grasslands, and anywhere there is a substantial amount of dead organic material. They are also found on or near plants and some are known to be plant pathogens.
Where they are found indoors: Basidiospores found indoors typically come from outdoor sources and are carried inside by airflow or on clothing. Certain kinds of basidiomycetes can grow indoors, such as those that cause “dry rot”, which can cause structural damage to wood. Occasionally, other basidiomycetes such as mushrooms can be found indoors, but this is not common. Generally, basiodiomycetes require wet conditions for prolonged periods in order to grow indoors.
Distribution: Chaetomium is a common mold worldwide. This genus contains around 80 – 90 different species.
How it is spread: Chaetomium spores are formed inside fruiting bodies. The spores are released by being forced out through a small opening in the fruiting body. The spores are then dispersed by wind, water drops, or insects.
Where it is found outdoors: Chaetomium can be found in soil, on various seeds, cellulose substrates, dung, woody materials and straw.
Where it is found indoors: Chaetomium can grow in a variety of areas indoors, but is usually found on cellulose based or woody materials in the home. It is very common on sheetrock paper that is or has been wet.
Distribution: Cladosporium is an abundant mold worldwide and is normally one of the most abundant spore types present in both indoor and outdoor air samples. This genus contains around 20 – 30 different species.
How it is spread: Cladosporium produces dry spores that are formed in branching chains. Spores are released by twisting of the spore-bearing hyphae as they dry. Thus, the spores are most abundant in dry weather.
Where it is found outdoors: Cladosporium is found in a wide variety of soils, in plant litter, and on old and decaying plants and leaves. Some species are plant pathogens
Where it is found indoors: Cladosporium can be found anywhere indoors, including textiles, bathroom tiles, wood, moist windowsills, and any wet areas in a home. Some species of Cladosporium grow at temperatures near or below 0(C) / 32(F) and can often be found on refrigerated foodstuffs and even frozen meat.
Distribution: Epicoccum is a cosmopolitan mold that includes only two species.
How it is spread: Epicoccum produces large dry spores that are easily dispersed through the air by wind.
Where it is found outdoors: Epicoccum can be found in soils or on plant debris.
Where it is found indoors: Epicoccum is commonly found on many different substrates indoors including paper, textiles, and insects.
Distribution: Penicillium / Aspergillus are two separate genera of molds that are so visually similar that they are commonly discussed together as a group. Together, there are approximately 400 different species of Penicillium /Aspergillus.
How it is spread: Penicillium / Aspergillus produce dry spore types that are easily dispersed through the air by wind. These fungi serve as a food source for mites, and therefore can be dispersed by mites and various insects.
Where it is found outdoors: Penicillium / Aspergillus are found in soils, decaying plant debris, compost piles, fruit rot and some petroleum-based fuels.
Where it is found indoors: Penicillium / Aspergillus are found throughout the home. They are common in house dust, growing on wallpaper, wallpaper glue, decaying fabrics, wallboard, moist chipboards, and behind paint. They have also been isolated from blue rot in apples, dried foodstuffs, cheeses, fresh herbs, spices, dry cereals, nuts, onions, and oranges.
Distribution: Stachybotrys is ubiquitous in nature. This genus contains about 15 species.
How it is spread: Stachybotrys produces wet slimy spores and is commonly dispersed through water flow, droplets, or insect transport, less commonly through the air.
Where it is found outdoors: Stachybotrys is found in soils, decaying plant debris, decomposing cellulose, leaf litter and seeds.
Where it is found indoors: Stachybotrys is common indoors on wet materials containing cellulose such as wallboard, jute, wicker, straw baskets, and other paper materials.
Distribution: Torula is a cosmopolitan micro fungus and includes approximately eight different species
How it is spread: Torula produces dry spores that are easily dispersed through the air by wind.
Where it is found outdoors: Torula is most common in temperate regions and has been isolated from soils, dead herbaceous stems, sugar beet roots, groundnuts, and oats.
Where it is found indoors: Torula is common indoors on wet materials containing cellulose, such as wallboard, jute, wicker, straw baskets, and other paper materials.
Distribution: Ulocladium is ubiquitous in nature and includes approximately nine different species.
How it is spread: Ulocladium produces dry spores that are easily dispersed through the air by wind.
Where it is found outdoors: Ulocladium is common outdoors in soils, dung, paint, grasses, wood, paper, and textiles.
Where it is found indoors: Ulocladium is common indoors on very wet materials containing cellulose such as wallboard, jute, wicker, straw baskets, and other paper materials. Ulocladium requires a significant amount of water to flourish.
References and Resources
Bioaerosols: Assessment and Control, Janet Macher, Sc.D., M.P.H., Editor. 1999. ACGIH, 1330 Kemper Meadow Drive, Cincinnati, OH 45240-1634.
Bioaerosols, Harriet Burge, Ph.D. 1995. Lewis Publishers, 2000 Corporate Blvd., N.W., Boca Raton, FL 33431-9868.
Biological Contaminants in Indoor Environments, Morey, Feeley, Otten, Editors. 1990. ASTM, 1916 Race Street, Philadelphia, PA 19103. STP 1071.
Fungi and Bacteria in Indoor Air Environments: Health Effects, Detection and Remediation, Proceedings from the International Conference, Saratoga Springs, NY October 6-7, 1994.
Health Implications of Fungi in Indoor Environments, Edited by R.A. Samson. 1994. Elsevier Science, P.O. Box 945, Madison Square Station, New York, NY 10159-0945.
Indoor Air and Human Health, Gammage & Kaye. 1985. Lewis Publishers.
Microfungi, S.G. Gravesen, J.C. Frisvad, & R.A. Samson, published by Munksgaard.
www.acgih.org American Conference of Governmental Industrial Hygienists – information on IAQ and useful links.
www.aiha.org American Industrial Hygiene Association – general IAQ information
www.calepa.ca.gov California Environmental Protection Agency – California IAQ resources
www.emlab.com EMLab P&K
www.epa.gov Environmental Protection Agency – information regarding prevention and remediation of mold
www.health.state.ny.us New York State Department of Health – New York state recommendations for IAQ, indoor mold inspections, remediation, and prevention
www.moldreport.com MoldREPORT™ – online store, and other information about MoldREPORT™
www.nih.gov National Institutes of Health – information regarding environmental health issues, including IAQ
www.niehs.nih.gov National Institute of Environmental Health Sciences – information on mold