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Pollen and Mold Center
Information About MOLDS

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Get readings about Mold aeroallergens.

Mold Types

Alternaria, Ascomycetes, Aspergillus, Basidiomycetes, Botrytis, Cercospora, Cladosporium, Curvularia, Drechslera, Epicoccum, Fusarium, Helminthosporium, Myxomycetes, Nigrospora, Penicillium, Periconia, Phoma, Pithomyces, Rhodotorula, Rusts, Smuts, Stachybotrys, Stemphylium, Torula and Trichoderma.

Mold Facts

  • Mold is a type of fungus. Other types of fungi include yeasts and mushrooms.
  • Sometimes the term mildew is used. It is also a type of fungus.
  • Molds reproduce by means of spores which commonly travel through the air.
  • Mold can look like a smudge, a discoloration, or even a stain.
  • Many smell musty or faintly like alcohol.
  • Mold's most important requirement is a source of moisture. (e.g., basements, bathrooms, kitchens, carpet, upholstery, soil)
  • Molds play an important role: as a part of the decaying process, as an antibiotic (Penicillin), and to flavor some cheeses.
  • Some varieties of molds are toxic.
  • Molds are strong allergens. However, most people are not allergic to molds.
  • They are most numerous in the warmer months, but can be found year round.
  • The spores can be inhaled or make contact through the eyes.
  • In many climates, for each pollen grain in the air there are 1000 mold spores.
  • Mold exposure increases with cutting the grass, raking dead leaves, or working with hay or mulch piles.


The Molds

Alternaria

  • Recognized as the chief fungal cause of hay fever.
  • Considered a dry weather spore. During dry periods, fungi increase in number until noon and decrease throughout the evening.
  • Alternaria is considered an "opportunistic fungi" being commonly found in dust in upholstery, carpet, mildew, pet areas, and airborne in homes.
  • In nature it is found in dead and dying plants and the soil.
Alternaria
Ascomycetes

  • Also known as ascospores, they are considered a wet weather spore. Plentiful during light rainfall or in pre-dawn hours when condensation is heavy.
  • Found everywhere in nature.
Aspergillus

  • Aspergillus is considered an "opportunistic fungi" being commonly found airborne and in mildew in homes.
  • Pose a danger indoors because they can grow in just a few days.
  • It is reported to be allergenic.
  • Found in warm soil, foods and dairy products.
  • Very similar to spores of Penicillium.
Aspergillus
Basidiomycetes

  • Also known as basidiospores, they are considered allergenic.
  • Considered a wet weather spore. Plentiful during light rainfall or in pre-dawn hours when condensation is heavy.
  • The spores are delicate and need the cool, moist conditions of spring and early summer.
  • Spores are not transported long distances or in large numbers.
  • These spores come from mushrooms, puffballs, and bracket fungi. Found in lawns, fields, parks, and wooded areas from spring through fall within a few days after rainfall.
  • In mushrooms and bracket fungi, the release of spores requires high humidity and so are most abundant in the pre-dawn hours.
  • In puffballs, spores are released as rain drops strike them, with strong gusts of wind, or when small animals hit them.
Botrytis

  • Reported to be allergenic.
  • It is parasitic on plants and soft fruits.
  • Found in soil and vegetables.
  • Possibly associated with allergic symptoms.
Cercospora

  • Parasite of higher plants, causing leaf spot.
  • Common outdoors in agricultural areas, especially during harvest.
Cladosporium

  • Considered a dry weather spore. During dry periods, fungi increase in number until noon and decrease throughout the evening.
  • Cladosporium is considered an "opportunistic fungi" being commonly found in upholstery, pet areas, in mildew, and airborne in homes.
  • Pose a danger indoors because they can grow in just a few days.
  • Found in dead and living plant material.
  • The most prevalent spore to be found in outdoor air samples.
Cladosporium
Curvularia

Drechslera

  • Is a common allergen.
  • Found in plant debris and soil.
  • Considered a plant pathogen of numerous plants, particularly grasses.
Epicoccum

  • Considered a dry weather spore. During dry periods, fungi increase in number until noon and decrease throughout the evening. Reaches its peak around 10 AM.
  • It produces spores rapidly and can grow under conditions of low humidity.
  • Has been reported to cause plant diseases in trees and damage crops such as millet, corn, soy beans and agricultural grasses.
  • Spores are buoyant and travel considerable distances in air.
  • A common allergen, but not "highly allergenic".
  • Found in a wide variety of plants, soil, air, human skin, insects, and a number of textiles.
  • Spores are at their peak from August to October.
Epicoccum
Fusarium

  • 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 toxins.
  • Reported to be allergenic.
  • Frequently involved in eye, skin and nail infections.
Helminthosporium

  • Reported to be allergenic.
  • Found in plant debris and soil.
  • Considered a plant pathogen of numerous plants, particularly grasses.
Myxomycetes

  • Known as slime molds because they secrete a slime trail across their habitat as they move.
  • Spores peak in early summer and into late fall.
  • Affected by temperature and moisture. They need protection from the drying effects of the wind and sun.
  • Tend to feed on bacteria.
  • Found in the forest where it is generally cool, moist, and shady.
  • Can be seen on decaying wood and in decaying leaves as colorful, shapeless structures.
  • It is not a major plant pathogen.
Nigrospora

  • Reported to be allergenic.
  • Rarely found growing indoors.
  • Found in decaying plant material and soil.
Penicillium

  • Penicillium is considered an "opportunistic fungi" being commonly found in upholstery, carpet, wallpaper, insulation, pet areas, in mildew, and airborne in homes.
  • Pose a danger indoors because they can grow in just a few days.
  • Outdoors it is commonly found in soil, food, cellulose and grains. It is also found in paint and compost piles.
  • Spores very similar to Aspergillus.
Penicillium
Periconia

  • Cause of root-rot disease in sorghum cultivars.
  • Found on the roots of various crops and dead plant stems.
  • Spores are abundant in the air, but allergenicity is not well known.
Phoma

  • A common indoor air allergen.
  • Found in soil and associated plants, particularly potatoes.
  • Produces pink and purple spots on painted walls.
  • It will grow on butter, paint cement and rubber.
Pithomyces

  • Spores found in dead stems, rotting leaves, paper, fodder grass, tree bark, and over 50 types of plants.
  • Is an early colonizer of dead material and, once established, lasts well into the fall season.
  • Spores are most abundant in the air between noon and 4 PM. Not as common in urban areas.
  • Its allergenicity is not well known, but is a possible allergen due to its ability to colonize and persist for long periods of time. More likely to be a factor in rural areas.
Rhodotorula

  • 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.
Rusts

  • It is a plant parasite.
  • Named because of brown or orange color of the spores.
  • The spores are designed to survive long distance transport.
  • Often continue to produce spores well into the fall season.
Smuts

  • Do not usually grow indoors.
  • Considered an allergen.
  • They are parasitic plant pathogens that require a living host for the completion of their life cycle.
  • Found on cereal crops, grasses, weeds, other fungi, and on other flowering plants.
  • Smuts are members of the Basidiomycetes.
Stachybotrys

  • Pose a danger indoors because they can grow in just a few days.
  • A slimy black mold rarely found indoors unless there has been water damage due to flooding or various leaks.
  • May contain poisons that can cause internal bleeding in the lungs of infants.
  • Because it needs cellulose to grow, it is found on drywall, ceiling tiles, and other materials containing paper or wood.
  • In nature it is found with decaying plant materials.
Stemphylium

  • Reported to be allergenic.
  • Isolated from dead plants and cellulose materials.
  • Although Stemphylium is rarely found growing indoors, it may be seen in dust as part of the normal influx of outdoor particles.
Torula

  • Reported to be allergenic.
  • Looks like a velvety black meal on various surfaces.
  • Found on dead plant stems and leaves, wood, dung, and several crops.
  • Spores are at their peak in the fall and late spring or early summer.
  • Rated as the second highest level of spores in the United States after Aspergillus.
Trichoderma

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