Dr Jackson Kung'u- Mold Specialist

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Dr. Jackson Kung’u (PhD)- Mold Specialist.
Phone: 905-290-9101
Mobile: 437-556-0254

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Indoor Air Quality

Mold Spores Contribute To Respiratory Disease And Allergic Reactions

It’s well established that airborne mold spores contribute to respiratory disease and allergic reactions in humans. Mold spores are everywhere and we inhale them every minute both when we’re indoors and outdoors. In cold countries airborne mold spores is highest during summer. During winter, the spore concentration outdoors is very low or absent altogether. In warm countries concentration of airborne spores may vary with the season (rainy or dry season) but there are spores present outdoors throughout the year. Usually the spore concentration indoors is lower than outdoors. However, in buildings with mold problem, the spore concentration could be very high.

Allergic reactions caused by mold spores

Inhaled mold spores can cause a number of health problems. Susceptible individuals react to proteins in the spore wall resulting in development of runny nose and eyes (allergic rhinitis) and asthma-like symptoms. Prolonged exposure to unusually high levels of spores can result in the development of allergic alveolitis.

Allergenic mold Spores

Spores commonly associated with allergy outdoors include spores of Cladosporium, Sporobolomyces, Didymella, and Alternaria. In buildings without mold problems, the same spores found outdoors would be present indoors but in lower levels than in outdoors. In buildings with mold problems a mix of species commonly found indoors and outdoors would be found. The indoor species would be in higher concentrations indoors than in outdoors.

In an indoor occupational environment the types of molds present would be determined by the indoor conditions and the work being carried out. For example in a compost facility thermotolerant fungi such as Aspergillus fumigatus would be present. Mold spores of some species such as Cladosporium and Penicillium may be detected in high numbers in air samples while others such as Eurotium, Wallemia, and Penicillium may be abundant in dust.

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.

Black Mould

Question:  My tenants are saying that there is black mould in my rental townhouse. I’ve replaced fixtures in the bathrooms, stopped leaks and spent thousands of dollars but they are still bringing in the local public health inspector.

I’m allergic to black mould myself and have been in while damaged drywall was being removed. I handled it myself with no ill effects and observed the joist cavities being treated with mould inhibiting sprays and ‘killex’.

Should I be worried that my tenants are still pursuing this investigation? I’ve taken every remedial step I can think of and the only stuff I saw was dried up and the rest looked like shower mildew to me. All the discoloration spots on the bathroom ceiling stuff came off with a cleaner called BAM and the paint was unaffected once the ceiling was wiped down.

Answer: Shower mildew is actually mould though it may not be what people call black mould (Stachybotrys chartarum). I would suggest you hire a qualified professional such as an industrial hygienist who is experienced in indoor microbial contamination. This person should be able to assess the extent of contamination, possibly determine the underlying cause, and then advise on the most appropriate level of remediation. They may also be able to advise you whether the tenants’ lifestyle could be contributing to mould growth. For instance, if they don’t switch the fan on (if there is one) when showering or bathing, then there will be mould growth due to condensation on the walls and the ceiling.

If you have further questions regarding black mould, please contact us at 905-290-9101.