Dr Jackson Kung'u- Mold Specialist

Helping People Resolve Mold Problems

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Dr. Jackson Kung’u (PhD)- Mold Specialist.
Phone: 905-290-9101

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Public Questions

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.

How Toxic is the Mould?

I have a question regarding mould. Thank you first off for someone that is passionate about what you love to do; its great how much you share about all that you know. I’ve been contacted by a young lady that needs information. She lives in Vancouver, BC in a rancher home built in the late 80’s, or early 90’s and she is having mould problems. She just discovered on a window sill, a yellow golfball-sized fungus, that has orange dots on it. When she touched it to clean, it burst and had green goo inside. She has had a persistent cough for several months now and when she talked to the landlord about the fungus, plus black staining in the bathroom, he threatened to evict them, as he just told them that he will paint over it and not to bother him again.

The Mould Stachybotrys

The Mould Stachybotrys is know to be toxic (toxigenic)

Question: Just how much should they be concerned and/or how toxic is the mould? She is an employee of mine and she had approached me as of today of the incident(s). I thank you in advance for your time.

Answer: It’s hard to tell the type of mould and whether it’s toxigenic or not from the description only. However, all moulds are potentially a health hazard and should be removed (not painted over). The source of moisture that is promoting mould growth should be identified and corrected otherwise mould will continue growing. As for your employee, the best thing to do if the landlord is not willing to remove the mould is to move out or to seek help/advice from the public health department who may compel the landlord to remove the mould. Before reporting to any authority she should be sure that the mould is growing due to the landlord’s negligence and not her own lifestyle.

Mold Exposure Limits

Question: My question regards mold exposure limits. I just had a mold count done in my home. The spore count levels in the basement were 5X and 6X outside air in the bedroom. Are these levels high enough to make someone sick? What are “high” levels? In other words are there mold exposure limits? Molds found were Penicillium, Aspergillus and ascospores. I spent a good deal of money on the testing and just would like someone else’s point of view, other than the guy wanting to sell me the remediation. Thank you.

Answer: Due to the large number of mold species and strains commonly found in buildings and the large inter-individual variability in sensitivity to mold exposure it has been difficult to set mold exposure limits. In other words there are no safe or unsafe levels of airborne mold spore counts that have been established. In absence of mold exposure limits, results from tests for airborne fungal spores cannot be used to assess risks to the health of building occupants. However, individuals who are immunocompromised are at higher risk of mold exposure than healthy individuals.

To minimize the risks of mold exposure it’s recommended to:

  • control humidity and diligently repair any water damage to prevent
    mold growth; and
  • clean thoroughly any visible or concealed mold growing in
    residential or office buildings.

These recommendations apply regardless of the type of mold found to be growing in the building.

Evaluating Mold Contamination In A Building

Question: If I want to evaluate mold contamination in a building, should I use air sampling of molds or ergosterol in dust?

Answer: The method to use to evaluate mold contamination in a building depends on the objective of the investigation and the resources available for the investigation. First let’s see what kind of data each method yields.
  • Air sampling For Mold

There are 2 methods currently used for sampling for airborne spores. These are air sampling for total fungal spore count (also referred to as nonviable analysis) and air sampling for culturable airborne fungal propagules (commonly referred to as viable analysis). The data obtained by the nonviable analysis are number of spores (or fungal elements if you include other fungal structures) per cubic meter of air. Viable analysis gives colony forming units (CFU) per cubic meter of air. Each of these 2 methods has it’s advantages and disadvantages. For example since non-viable spore analysis depends on the morphology and sizes of spores alone, identification is limited to only a few groups of fungi that have spores with unique characteristic. A vast majority of spores are reported as unidentified since it’s difficult to tell which group of fungi produced them.

The major advantage of nonviable analysis is that since the analysis does not depend on the viability of the spores, all spores present in the sample can be counted whether they are dead or alive. This brings us to the major disadvantage of analysis. If 95% of fungal structures contaminating the air were dead, this method would detected only 5% of the contamination.

The advantage of culturable sampling is that the recovered molds could be identified to species level. This is important because some important characteristics such as production of mycotoxins or pathogenicity are species (and sometimes strain) specific.

Given the advantages and disadvantages of the 2 air sampling methods, an investigator has to decide which method to use. In some cases, using a combination of the 2 methods is recommended.

  • Dust Sampling For Ergosterol

Ergosterol is the major sterol in the cell membranes of fungi (yeasts and mold). It’s present in mycelia, spores, and vegetative cells. There is a strong correlation between ergosterol content and fungal dry mass. Ergosterol content has, therefore, been widely used as an estimate of fungal biomass in various environments, such as soil and aquatic systems. Ergosterol measurements have been proposed as a new method for determination of total fungal biomass in investigations of indoor environments. One limitation about this method is that the amount of ergosterol in fungal tissue is not constant and varies with fungal species, age of the culture, developmental stage (growth phase, hyphal formation, and sporulation), and growth conditions (growth media, pH, and temperature). Another limitation is that ergosterol measurements cannot be used to determine the species present in the dust sample since it’s not genera or species specific. The method is currently not widely used and very few commercial laboratories have the capability to analyze for ergosterol in dust.

A Useful Ergosterol Reference

ANNA-LIISA PASANEN, KATI YLI-PIETILÄ , PERTTI PASANEN, PENTTI KALLIOKOSKI, AND JUHANI TARHANEN (1999). Ergosterol Content in Various Fungal Species and Biocontaminated Building Materials. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Vol. 65, No. 1: 138–142.

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.