Fire Safety.
(Note: The information below was provided to me to use on my website and has been authorized by Amerispec home inspection services of Mississauga)
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General Industry topics related to Homes, home inspectors and home inspection issues
Mould
I’ve heard about mould in the media lately. I’ve heard it
can be toxic and that some people have become ill
due to exposure to mould in certain areas, such as in
portables and wet basements. Just what is mould,
and is it really a health concern? |
Moulds are forms of fungus (mildew, yeast and mushrooms are other forms of fungus) that grow indoors and outdoors. People are exposed to mould spores (i.e. airborne "seeds") daily in the air they breathe; however, sometimes moulds grow excessively in certain areas called "amplification sites" (see below for further information) and can cause different types of illnesses. Some moulds are more hazardous than other moulds, and different people have different responses to mould exposure. In particular, those with allergies, existing respiratory conditions or suppressed immune systems are especially susceptible to health problems from mould exposure. Additionally, infants and children, pregnant women, and the elderly can be sensitive to the effects of
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mould exposure. Some people that are exposed to mould experience allergic reactions, with symptoms similar to hay fever and the commoncold but that last for longer periods, while others can experience aggravation to asthma. Researchers have identified that some fungi in indoor environments can induce allergic and irritant response, infectious disease, respiratory problems, hypersensitivity reactions, and organ toxicity. In addition, some moulds produce chemicals called mycotoxins, which can cause flu-like symptoms. It should be noted that the causes and effects of mould exposure on people are not very well understood. In some cases, health problems that are attributable to mould are temporary and can be controlled by limiting exposure to moulds. |
What factors affect mould growth? |
Several factors affect mould growth, including:
- Nutrient availability—nutrients absorb moisture to maintain a favorable environment for mould growth, and include many surfaces such as soil, dirt, wood, cellulose (paper, ceiling tile, jute carpet backing, cork, pipe wrap), some forms of insulation, fabric, oil, etc.
- Moisture content—the amount of moisture in a material influences
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how an organismcan support growth. Moisture sources include condensation in humid rooms, on windows, walls, unheated closets, dampness under carpets and on shower curtains, and periodic wet sections in ductwork of air conditioned ventilation. |
- Temperature—Temperature is also a factor that affects mould growth; moulds typically require temperatures between 5°C and 38ºC to grow.
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What is an Amplification site? |
As mentioned above, buildings are not sterile; the presence of mould spores is very common in most buildings. It is interesting to note that the mere presence of mould spores in a building is not a concern; the concern arises when |
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mould areas have grown in a building. When areas in a building have suitable nutrient and moisture content that fosters mould growth, the area is called an amplification site. |
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Can mould be easily identified in homes
by a visual inspection? |
No. Past studies have indicated that up to 90% of mould growth is not visible at the surface. Certain school boards have found a very poor correlation between the results of visual (surface) inspections and subsequent invasive inspections
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in portables in Ontario. Certain guidelines state that invasive inspection is necessary to make a complete assessment of the extent of mould contamination in a building. |
HELPFUL TIP
Moisture is one of the key factors that affect mould growth. There is very little time after a flood to prevent development of an amplification site. Buildings are not sterile and pre-existing mould spores will begin to develop rapidly with the proper nutrient, moisture and temperature combinations. It is considered good practice to remove water very quickly (within 24 to 48 hours) after flooding. Surface moisture should be reduced to below 70% relative humidity as soon as possible to reduce the potential for mould growth. |
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