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Common Indoor Moulds & Their Hazard Classes

This is a list of some of the most common indoor moulds and their hazard classes. For an explanation of these hazard classes, read the May 24 post entitled “Indoor Moulds: Hazard Classes And Associated Health Effects”. The list is not exhaustive. At least 150 moulds have been reported from buildings.

Acremonium spp (hazard class B).
Alternaria spp (hazard class B).
Aspergillus flavus (hazard class A).
Aspergillus fumigatus (hazard class A).
Aspergillus versicolor (hazard class A).
Aureobasidium pullulans (hazard class B).
Chaetomium globosum (hazard class C).
Cladosporium cladosporioides (hazard class B).
Cladosporium sphaerospermum (hazard class C).
Fusarium spp (hazard class A).
Mucor spp (hazard class A).
Paecilomyces spp (hazard class B).
Penicillium aurantiogriseum (hazard class B).
Penicillium chrysogenum (hazard class B).
Scopulariopsis spp (hazard class B).
Stachybotrys chartarum (hazard class A).
Trichoderma spp (hazard class B)
Ulocladium botrytis (hazard class C).
Wallemia sebi (hazard class C).

These moulds are commonly found on water damaged or damp surfaces in kitchens, basements, bathrooms, ceilings, and other drywalls. Occurrence of some of these moulds such as Stachybotrys, Fusarium, Ulocladium and Trichoderma in a building is an indication of serious water damage.

Do you have a question concerning indoor moulds? Send your question to My Question.

Indoor Moulds: Hazard Classes and Associated Health Effects

Hazard classes of indoor mould
Indoor moulds have been grouped into 3 hazard classes based on associated health risk. These classes are similar to risk groups assigned to micro-organisms handled in laboratory environments.

  • Hazard Class A: includes fungi or their metabolic products that are highly hazardous to health. These fungi or metabolites should not be present in occupied dwellings. Presence of these fungi in occupied building requires immediate attention.
  • Hazard class B: includes those fungi which may cause allergic reactions to occupants if present indoors over a long period.
  • Hazard Class C: includes fungi not known to be a hazard to health. Growth of these fungi indoors, however, may cause economic damage and therefore should not be allowed.

Health Problems Associated With Indoor Moulds
Exposure to indoor mould has been associated with the following health problems:

  • Lower respiratory symptoms such as coughing and wheezing;
  • Respiratory infections such as aspergillosis;
  • Allergic diseases, including allergic asthma and bronchitis;
  • Non-inflammatory, unspecific symptoms, such as eye and skin irritation, fatigue, headache, nausea, and vomiting.

Should you have a question concerning indoor moulds send it to me at My Question.

Salmonella food poisoning and symptoms

Salmonella food poisoning has been a growing concern in recent news. It has frequently lead to recalls of beef, salads and organic products and, even peanut butter products. Salmonella food poisoning occurs when one eats raw or undercooked foods such meat, poultry, eggs or egg products. Properly cooked food can get contaminated with Salmonella if […]

Legionella pneumophila – Guidelines for Laboratory Interpretation

Legionella pneumophila is a Gram negative, aerobic bacteria that is characterized as an opportunistic pathogen. It is the cause of Legionnaires’ Disease, a severe form of pneumonia and, it is the cause of Pontiac fever, a non-pneumonic form of L. pneumophila infection. Legionella spp.’s mode of transmission is through aerosols or aspiration of contaminated water. The Public Health […]

The Indoor Mold Is An Early Warning Device

The mold (or mould, in the Queen’s English) has been the victim of a bad press. Mention the word and it conjures up an image of something rotting or in the process of decomposition. And yet, were it not for the mold that inspired the discovery of penicillin millions of lives would have been lost. […]