The negative health effects of mold allergens have been widely recognized, with the risk of exposure more prevalent than originally suspected. Molds are forms of fungi that are found indoors and outdoors. There are an estimated 1.5 million species of fungus worldwide, of which nearly 70,000 have been characterized.  In normal conditions, exposure presents no prevalent health problems. Contamination becomes an issue when mold is exposed to excessive moisture caused by flooding, roof leaks, high humidity, dampness, condensation, etc.  Airborne mold spores are microscopic, thus visual detection is impossible.
Molds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may cause allergic reactions in susceptible individuals.

Type: Cladosporium

Description: Most frequently found fungus in outdoor air. Indoors, usually occurs at low concentrations in damp or humid areas, but may be found in high concentrations in water-damaged building materials. Its ability to sporulate heavily and to get airborne makes it an important fungal allergen. Some species produce a mycotoxin, epicladosporic acid that acts in an immunosuppressive manner.

Possible Health Effects: hay fever, common allergies, fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin, one species can cause chronic subcutaneous infection

Type: Ascospores

Description: Common in nature and commonly found in the outdoor environment. This group is a possible mycotoxin producer.

Possible Health Effects: possible allergens, opportunistic human pathogens

Type: Basidiospores

Description: Spores that are produced by a class of fungi called basidiomycetes. Includes the mushrooms, toadstools, boletes, wood bracket fungi, and puffballs. Basidiospores have the potential to produce a variety of toxins. Members of this family produce type I and III fungal hypersensitivity reactions.

Possible Health Effects: hay fever, asthma, eczema, pneumonitis, allergic alveoltis, fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin

Type: Penicillium/Aspergillus group

Description: Many species are common contaminants on a variety of substrates. May be found indoors in air samples, carpet dust, or on wallpaper. Some species are able to produce mycotoxins. There are over 175 different aspergillus species and they can produce type I and III fungal hypersensitivities. There have been over 15 different species of aspergillus implicated in either producing mycotoxins or other harmful health effects.

Possible Health Effects: allergic reactions, keratitis, hypersensitivities and pneumonitis. Most of these symptoms occur if the individual is immunocompromised in some way (HIV, cancer, etc). Commonly produces allergic reactions such as hay fever, asthma, eczema, pneumonitis, allergic alveoltis, fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin

Type: Alternaria

Description: Common saprobe found on decaying wood, decaying plants, food, soil, and outdoor air. Some species are plant pathogens. It is one of the more common fungi found in nature. Indoors, it can be found in house dust, carpet, damp areas around showers and window frames, and anywhere condensation occurs. Because of its abundance and ubiquity, alternaria is one of the most important fungal allergens.

Possible Health Effects: one of the most important fungal allergens and is recognized as the chief fungal cause of hay fever characterized by fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin

Type: Drechslera/Bipolaris group

Description: These groups of fungi constitute the most commonly reported causes of allergic fungal sinusitis. They produce type I fungal hypersensitivity in humans.

Possible Health Effects: hay fever, asthma, eczema, fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin

Type: Curvularia

Description: Curvularia species is found on plant material. It has been reported to cause type I hypersensitivity

Possible Health Effects: hay fever, asthma, eczema, fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin

Type: Stachybotrys

Description: Grows indoors on water-damaged cellulose rich materials, such as sheet rock, paper, ceiling tiles, insulation backing, gypsum board, and wallpaper. The presence of this fungus can be significant due to its ability to produce mycotoxins under certain environmental conditions. Exposure to the toxins can occur through inhalation, ingestion, or skin exposure. It has a worldwide distribution.

Possible Health Effects: hay fever, asthma, eczema, dermatitis, cough, rhinitis, headache, fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin. It is possible that stachybotrys may play a role in the development of sick building syndrome.

Type: Torula herbarum

Description: Typically found in wood containing materials. Reported to produce type I fungal hypersensitivity.

Possible Health Effects: hay fever, asthma, eczema, fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin

Type: Chaetomium

Description: This genus is found on materials containing cellulose, or other wet materials. Chaetomium can produce type I fungal hypersensitivity. It can also produce mycotoxins.

Possible Health Effects: hay fever, asthma, eczema, nail infections, fatigue, runny nose, sneezing, stuffy nose, plugged ears, watery/bloodshot eyes, itchy eyes / nose / ear canal / skin