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Is There A Way To Estimate Length Of Time A Fungal Colony Has Been Growing?

Question: Is there a way to estimate the length of time a fungal colony or colonies have been growing? I’m sure that is based on the type of mold, water availability, temperature, food availability, etc. However, in the district we have found several mold growth areas that appear to have been active for several weeks (based totally on assumptions), not a matter of days as is relayed in the information provided.

Answer:. It’s difficult to tell the length of time a fungal colony or colonies have been growing. As you mentioned the rate of fungal growth will depend on water availability, temperature, food availabity, presence/absence of
growth inhibitors and most important the type of fungus. If we know the type of fungus and if it’s still actively growing,
then we can estimate the length of time the fungal colony has been growing. Under laboratory conditions, most fungi will
produce visible colonies in 3-5 days (some fast growing ones within 2 days) and produce spores within 5-10 days.

Are These Levels of Spores Considered Hazardous?

Question: The crawlspace in our condo has the following readings for spores/m3 : Aspergillus/Penicillium type-16000; Chaetomium- 67; Cladosporium- 227. Are these levels spores considered hazardous? It is going to cost a very high amount to have vents, sensors and spores removed to correct the situation and there is no guarantee. Please give me your comments on this.

Answer: There are no published standards for acceptable exposures to indoor mold spores. And there is no agreement among the scientific community on the exact levels of airborne indoor mold spores which are responsible for the onset of disease, nor is there adequate information on dose-effect relationship.

This is what Health Canada advises:

Health Canada considers that mould growth in residential buildings may pose a health hazard. Health risks depend on exposure and, for asthma symptoms, on allergic sensitization. However, the large number of mould species and strains growing in buildings and the large inter-individual variability in human response to mould exposure preclude the derivation of exposure limits. Therefore, Health Canada recommends:

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

These recommendations apply regardless of the mould species found to be growing in the building.

Further, in the absence of exposure limits, results from tests for the presence of fungi in air cannot be used to assess risks to the health of building occupants.”

For more information regarding mold spores please call us at 905-290-9101 in Ontario or 604-435-6555 in British Columbia.

Mold In The House And Air Quality

Question: My question regards mold in the house and air quality. I have a tenant complaining about the air quality in a house I own. It’s a very clean 15 year old home and the basement carpet is 4 years old and in excellent condition. There are no damp conditions and the climate is very dry here. I think this is a frivolous complaint giving him reason to vacate and break our lease agreement. There are no noticeable smells or signs of mold in the house or moisture anywhere in the house. In September clean water entered the basement from a broken sprinkler that was just next to the window. Within 3 hours we had thoroughly shop vaccumed about 3 gallons out of the carpet and pad, sprayed the concrete, pad and carpet with Pinesol. We then separated the layers with 2X2’s and paint cans, set up fans and opened the windows. We relaid the dry pad and carpet on the 4th day. There was no mildew stains and the musty carpet smell was minimal and had dissipated completely within 2 weeks. My tenant’s wife has Asthma and allergies. They had the house inspected and 7,553 Aspergillus/penicillium spores per cubic meter of air were shown in the basement on the report and 2071 on the main floor. Are these spores a health risk? Does this mean there is excessive mold in the house? Is this an uncommon condition for a basement? Do you think this condition was caused by the wet carpet from 4 months ago? Since there is no musty smell would these spores be dormant? Should I replace the carpet? Is the source of these spores likely to be from somewhere else in the house? Should I hire another test from a different company? I appreciate your input.

Thanks.

Answer: Thank you for your question(s). It’s common to have mold in the house. Currently there are no permissible levels for airborne mold spores. The large inter-individual variability in human response to exposure to different mold species and strains makes it difficult to set exposure limits. Therefore, 7,553 aspergillus/penicillium spores per cubic meter of air could be a problem to some people and not to others. Health risks depend on exposure and, for asthma symptoms, on allergic sensitization.

You have mentioned that your tenant’s wife has a history of asthma and allergies. This suggests that she could be at risk. Growth of mold in the house is due to presence of moisture. It’s possible that there were some areas that didn’t get completely dry within 48 hours and hence the growth of species of Aspergillus and/or Penicillium. These molds do not require a lot of moisture for growth. You may consider hiring a qualified professional with experience in mold investigation to come and try to determine the source of those spores and also determine whether there are still some moisture issues that you’re not aware of. They should also be able to advise you whether it’s necessary to replace the carpet or not.

Spores of Aspergillus and Penicillium species could remain dormant for many years. It’s known that even dead spores can cause allergic reactions to those who are sensitive to mold. As for your tenant, I would suggest you let them go. While the tenant’s asthma and allergies may have nothing to do with mold in the house, it’s perhaps better to let them go for their peace of mind and as a show of good will on your part.

I hope you found my comments useful. Please feel free to contact me again if you have any other questions.

Dr. Jackson Kung’u.

Moulds commonly found in carpet and mattress dust

A number of moulds are frequently found in carpet and mattress dust. Eurotium repens is the most frequently detected mould in mattress dust. Others include Aureobasidium pullulans, Alternaria alternata, Penicillium chrysogenum, Aspergillus penicilloides and Aspergillus restrictus.

More than 100 species of moulds have been recorded from carpet dust. As with mattress dust, the most frequently isolated mould in carpet dust is Eurotium repens. The others are Penicillium chrysogenum, Alternaria alternata, Aureobasidium pullulans and Phoma herbarum.

Concentrations of these moulds in carpet and mattress dust can be as high as 70 million colony forming units per gram of dust. Such high concentrations of moulds are likely to cause respiratory allergy or irritating symptoms. Therefore, it is import to regularly HEPA vacuum the carpets, mattresses and upholstered furniture to reduce the dust and spore concentration. If people are suffering from reoccurring respiratory allergy or irritating symptoms in a building where there is no visible mould, it is suggested that dust be tested for the types and concentrations of mould present.

Can Water Grow Mould?

One of our website visitors wondered if mould can grow in water. Mould can grow in water and if the water is rich in nutrients, the mould will form a mat on the surface of standing water and produce spores. If the water contains little or no nutrients, then the initial growth would die for lack of nutrients.

There are some moulds that thrive well only in water. For more information about mould, contact us at (905)290-9101.

Salmonella food poisoning and symptoms

Salmonella food poisoning has been a growing concern in recent news. It has frequently lead to recalls of beef, salads and organic products and, even peanut butter products. Salmonella food poisoning occurs when one eats raw or undercooked foods such meat, poultry, eggs or egg products. Properly cooked food can get contaminated with Salmonella if […]

Legionella pneumophila – Guidelines for Laboratory Interpretation

Legionella pneumophila is a Gram negative, aerobic bacteria that is characterized as an opportunistic pathogen. It is the cause of Legionnaires’ Disease, a severe form of pneumonia and, it is the cause of Pontiac fever, a non-pneumonic form of L. pneumophila infection. Legionella spp.’s mode of transmission is through aerosols or aspiration of contaminated water. The Public Health […]

The Indoor Mold Is An Early Warning Device

The mold (or mould, in the Queen’s English) has been the victim of a bad press. Mention the word and it conjures up an image of something rotting or in the process of decomposition. And yet, were it not for the mold that inspired the discovery of penicillin millions of lives would have been lost. […]