TYPES OF MOULDS FOUND IN HOMES

Moulds are a common presence in our homes and workplaces, often thriving in damp or decaying environments. While some moulds are harmless, others pose risks to health, causing allergies or more severe reactions. Below is an overview of the most common household moulds, their sources, and potential impacts on human health.

Indicator species of mould refer to specific types of mould that signal the presence of conducive conditions for mould growth, such as persistent moisture or water intrusion. These species are often used as markers to identify areas where mould may be proliferating and to assess the extent of the issue. The detection of an indicator species suggests the need for further investigation to locate and address the underlying source of moisture or contamination.

Here is a list of common mould species often considered indicators of specific environmental conditions or contamination:

• Stachybotrys chartarum (Black Mould)
  
• Aspergillus species
  
• Penicillium species
• Cladosporium species - note this species is also prevalent outdoors and indoor samples need to be compared to an outdoor control to determine if poor air quality exists
• Chaetomium species
• Fusarium species - not typically observed in Alberta Buildings
• Alternaria species
• Aureobasidium species - not typically observed in Alberta Buildings
• Ulocladium species
• Trichoderma species
  

These mould species serve as markers for assessing indoor air quality and determining the presence of hidden water or moisture issues. Their detection warrants further investigation to identify and address the root causes.

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Alternaria

• Description: A large genus of fungi often found on decaying plants. These spores can be found in buildings where there has been a water intrusion event.
• Sources: Soil, water, and plant debris.
• Health Risks: Can trigger allergic reactions, such as hay fever.

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Alternaria spores

Ascospores

• Description: A group of spores (Phylum Ascomycota) produced in a sac like structure known as an ascus. These spores are common in outdoor and indoors environments in Alberta. Their presence is not indicative of poor air quality.
• Sources: Damp indoor surfaces.
• Health Risks: Released upon maturity and may cause respiratory irritation.

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Ascospores

ASPERGILLUS

• Description: Aspergillus can thrive on a wide range of surfaces, including nutrient-poor environments such as damp walls (especially drywall). Under microscopic examination, its spores closely resemble those of Penicillium and are often reported as "Aspergillus-Penicillium-like." Elevated concentrations of these spores typically suggest the presence of a nearby source of contamination.
• Source: Damp walls, ceilings, and other moisture-prone areas. Starchy foods such as bread and rice. Commonly found outdoors such as soil, compost, and decaying vegetation.
• Potential Health Risks: Exposure to Aspergillus spores may pose health risks, particularly for individuals with compromised immune systems or respiratory conditions such as allergic reactions (sneezing, coughing and skin irritation.  Infections such as aspergillosis.

Aspergillus

Basidiospores

• Description: A group of spores (Phylum basiodiomycete) such as mushrooms rusts, smuts and puffballs.  These spores are common in outdoor and indoors environments in Alberta. Their presence is not indicative of poor air quality.
• Sources: Airborne; germinates on favorable surfaces.
• Health Risks: Can form hyphae, potentially causing skin conditions like ringworm.

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Basidiospores

Bipolaris

• Description: Fungi associated with plant diseases.
• Sources: Plant material and soil.
• Health Risks: May cause allergies and release mycotoxins in some cases.

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Bipoloaris spores

Chaetomium

• Description: A dark mould found in soil and plant debris.  Chaetomium is commonly found in water-damaged materials such as drywall, insulation, and wood. 
• Sources: Damp sheetrock and air indoors.
• Health Risks: Contaminant removed through proper hygiene.

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Chaetomium Spores

Curvularia

• Description: Thrives in tropical climates but can appear in temperate zones. Typically found in outdoor air in Calgary in June and early July
• Sources: Plants and soil.
• Health Risks: Rarely harmful but may contribute to allergies.

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Curvularia Spores

Hyphal Fragments

• Description: Components of fungal growth without specific genus identification.
• Sources: Various damp or decaying environments.
• Health Risks: May cause mild respiratory irritation.

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Penicillium

• Description: Soil fungi found in cooler temperatures.
• Sources: Organic material, including food and paper products.
• Health Risks: Produces mycotoxins; may cause allergies, infections, or food spoilage. Elevated Aspergillus and Penicillium species when compared to the outdoor control sample is an indicator of a potential source within the area.

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Penicillium Spores

Pithomyces

• Description: Pithomyces is a very common mold in the outdoors. Thriving in dark, damp environments, it primarily grows in soil and in piles of dead leaves. If this mold comes indoors, it can grow on damp paper and has been found in ceiling tiles, carpeting and mattress dust. 
• Sources: Paper materials and damp environments.
• Health Risks: Can trigger mild allergies.

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Pithomyces Spores

Stachybotrys (Black Mould)

• Description: Found on water-damaged materials like drywall and wallpaper. Commonly found on drywall after water intrusion events.
• Sources: Soil, decaying plants, and damp surfaces.
• Health Risks: Produces mycotoxins; can cause allergic reactions and respiratory issues.

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Stachbotrys Spores

Stemphylium

• Description: Similar to Alternaria in its allergy-triggering potential. Not typically found indoors unless there has been a water intrusion event.
• Sources: Leaves, soil, wood, and vegetation.
• Health Risks: Rarely found indoors but can cause hay fever-like symptoms.

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Stemphylium Spores

Ulocladium

• Description: Requires high moisture levels to thrive.
• Sources: Soil, textiles, and water-damaged materials.
• Health Risks: Common allergen for individuals with asthma or hay fever.

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Ulocadium Spores

HOW TO MANAGE AND PREVENT MOULD GROWTH

• Reduce Humidity: Use dehumidifiers in damp areas.
• Improve Ventilation: Ensure proper air circulation in bathrooms, kitchens, and basements.
• Fix Water Leaks: Address plumbing and roof issues promptly.
• Clean Regularly: Keep surfaces dry and clean, especially in moisture-prone areas.

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Understanding the types of moulds and their potential risks can help you maintain a safe and healthy environment in your home or workspace. If you suspect a mould problem, consult a professional for testing and remediation.

Contact Western Health & Safety