Dr Jackson Kung'u- Mold Specialist

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Dr. Jackson Kung’u (PhD)- Mold Specialist.
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mold growth

Aspergillus/Penicillium in the Basement

Question: Is Aspergillus/Penicillium spore count in the basement high? We have this smell in our house for some time. We have also arranged for the gas company to come to see if there is gas leak. Last week, we had an air sample taken from our house. The Aspergillus/Penicillium reading from outside was 267 spores/m3 and the reading from the basement was 26,667 spores/m3. I do not know if these readings indicate any significance. Do you have any suggestions for the cause and solutions? Thank you very much for your help.

Answer: I think the Aspergillus/Penicillium spore count in the basement suggests persistent humid conditions. You may want to hire a professional to come and assess the extent of mold growth in the basement, identify the cause (i.e., moisture source) and suggest the best method to fix the moisture problem and remove the mold safely. To control the growth of mold such as Aspergillus/Penicillium the humidity in the basement has to be reduced to a level below 60%. The following techniques can help control moisture in the basement:

  1. Fix leaks, drips, and seepage problems.
  2. Dry wet areas within 24 to 48 hours to prevent mold growth. Thoroughly clean and dry water-damaged carpets and consider removal and replacement of items that appear to be permanently water damaged. Mold and mildew on hard surfaces can be washed and the surfaces dried completely.
  3. Do not finish a basement below ground level unless all water leaks are sealed. A finished basement should also have adequate outdoor ventilation and heat to prevent condensation.
  4. Operate a dehumidifier in the basement, if necessary, to keep relative humidity levels down. But keep in mind a dehumidifier can be expensive to operate.

Mold In Bathrooms

Growth of mold in bathrooms is very common if there is no proper ventilation. Mold in bathrooms could be due to poor ventilation and high humidity in the bathroom.  The mold could be found growing on the walls and also the bathroom ceiling. Severe growth of  mold in bathrooms can also occur in drains which emit odors. Drains are a hot spot for fungal growth in bathrooms. The extent of fungal contamination in bathrooms is dependent on the amount of moisture present.

Predominant types of mold in bathrooms include Acremonium sp., Cladosporium sp., Cladophialophora sp., Fusarium sp., Phoma sp., Exophiala sp.,  Scolecobasidium sp., and Aureobasidium sp. With leaking pipes or prolonged excessive moisture other indicators of moisture damage such as Stachybotrys sp and Chaetomium can be found growing behind the baseboard.

How to control growth of mold in bathrooms

To control growth of mold in bathrooms, humidity has to be reduced. The CMHC recommends the following:

  • Check the bathroom fan to make sure it exhausts to the outside.
  • Turn the bathroom fan on when you shower. Keep it running for a few minutes after you finish your shower.
  • Take short showers.
  • Keep surfaces that get wet, such as the walls around the bathtub and shower, clean and dry.
  • If there is a carpet in your bathroom, remove it.
  • Check for water leaks.
  • Keep drains in good shape by removing debris from them.

How To Get Rid Of Mold Growth

Many people and even institutions would be happy if they could find a way of getting rid of mold. Unfortunately it’s almost impossible to get rid of mold completely. However, if we understand the conditions that support mold growth, we could then try to manipulate those conditions so as to control mold growth. Mold growth has the following requirements:

1. Presence of spores or mold fragments that are capable germinating (viable) and developing into new mold growth.

2. Moisture. Like any other living organism mold requires water for growth.

3. Nutrients. Nutrients are readily available as some components of building materials are made of easily degradable organic materials. Nutrient are also available in dust.

4. Suitable temperature. For most indoor molds the optimal temperature for growth is between 20 and 25 oC.

The last two mold growth requirements would be difficult to manipulate. As mentioned above some materials in buildings are readily degradable by microorganisms. As for the temperature, mold can grow at a wide range of temperature and it’s optimal temperature is similar to that required in buildings for human comfort.

To control mold growth, therefore, we need to try and reduce or eliminate spores/mold fragments and water in our buildings. We could reduce the amount of spores and/or mold fragments settled on interior surfaces in buildings by HEPA vaccum cleaning all surfaces that are prone to dust on a regular basis.

To be able to control moisture, we need to understand the sources and also the mechanisms by which moisture moves through the building. The primary sources of moisture in buildings include:

1 . Liquid water, from precipitation (rain and melting snow) or plumbing leaks;

2. Water vapor (condensation), from the exterior and from activities and processes within the building;

3. Liquid and vapor from the soil adjoining the building;

4. Moisture built-in with materials of construction or brought in with goods and people

 Controlling moisture in the building may require the help of a professional who understands the processes by which moisture moves in and through the building. To completely get rid of mold growth in a building is difficult.

 

Air Quality Mold Testing Kits

Air quality testing should be conducted by a qualified professional. However, there are basic tests that a homeowner or a property manager can perform by themselves and save money. Air quality testing for mold does not require any special training. Mold & Bacteria Consulting Laboratories has been renting air quality testing equipment to homeowners, property managers or professionals who are just starting their businesses.

To perform your own air quality testing for mold it’s important to plan ahead. For example you need to decide how many rooms you want to test as this will determine the number of air samples you will collect. ideally, one should test all the rooms but if the budget cannot allow you can test areas of concern. In addition to the samples you collect from indoors, an outdoor sample is also required. The outdoor air sample helps to determine which of the mold spores detected indoors had likely originated from outdoors.

Interpreting air sample results can be difficult. However, after comparing indoor samples with outdoor sample, if the types of spores detected from the indoor sample are the same as those detected from outdoors and the indoor counts are significantly lower than those of the outdoors, then we can conclude that the tested areas had no mold problem at the time of testing. This conclusion is only valid if we cannot visually see mold growth and the building is not damp. It’s important to note that while the spore counts could be low, presence of certain types of molds could be an indication of major moisture damage and possibly hidden mold growth.

 How to perform air quality testing

As indicated previously you’ll require to rent an air sampling pump. You’ll also need to purchase air sampling cassettes. Mold & Bacteria Consulting Laboratories provides instructions on how to operate the pump. After sampling the samples are sent to the laboratory for identification and counting of spores. The results are reported as the number of spores per cubic meter of air. Click air sampling instructions to watch a video on how to perform air quality test for mold.

Crawlspace Mold Growth

Question: I have an 8 year old home in BC’s Gulf Islands. On a recent trip into my crawlspace noticed some mold growth or fungus on the underside of the vapor barrier that is applied over the earth in the crawlspace. There is no sign of any mold growth elsewhere. The crawlspace has four vents that have been opened all summer, and I see no moisture in the crawlspace except some water droplets probably condensation under the vapor barrier. The concrete walls of the foundation are insulated and the crawlspace is correctly vented. Should I be concerned, should I close the vent’s over winter, or is there anything else I should do to stop this.

Thanks.

Answer: If you only noticed minor mold growth on the underside of the vapor barrier, you don’t have to be concerned. However, I would suggest you continue monitoring the entire crawlspace and if you see mold growing on wood, it’s an indication that the crawlspace is damp enough to support mold growth. In that case I would recommend that you consult a professional experienced in building foundation to determine the cause of dampness and how it may be rectified. As long as the the crawlspace is damp there will be mold growth.