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Mould Is A Major Problem In Many Homes In British Columbia

The damp climate in British Columbia is ideal for mould growth. It is recommended that homeowners or property managers regularly check their buildings for mould growth or water damage in order to correct the problem before it gets out of hand. For people looking for homes to rent or buy, it’s important that you check for signs of mould before moving into a place and take every step possible to prevent mould in your home. Some of the activities that may lead to mould growth include cooking, washing clothes or showering without venting out the moisture. As for tenants, finding mould may not be reason enough to break a tenancy agreement and move out of a place early. Furthermore, your landlord may blame you for causing the mould problem if mould growth was due to your lifestyle.

How To Control mould Growth

  1. Reduce Indoor Humidity By:
    • Venting showers and other moisture-generating sources to the outside.
    • Controlling humidity levels and dampness by using air conditioners and de-humidifiers.
    • Providing adequate ventilation to maintain indoor humidity levels between 30-60%.
    • Using exhaust fans whenever cooking, dishwashing, and cleaning.
  2. Inspect the home regularly for signs of mould, moisture, leaks, or spills. The following suggest possible mould growth:
    • Mouldy or musty odours.
    • Water stains or discoloration on ceiling, walls, floors, and window sills.
  3. Respond promptly when you see signs of moisture and/or mould, or when leaks or spills occur:
    • Clean and dry any damp or wet building materials and furnishings within 24-48 hours of occurrence to prevent mould growth.
    • Fix source of water problem or leak to prevent mould growth.
    • Clean mould off hard surfaces with water and detergent, and dry completely.
    • Absorbent materials such as ceiling tiles, that are mouldy, may need to be replaced.
  4. Prevent moisture condensation:
    • Reduce potential for condensation on cold surfaces (i.e., windows, piping, exterior walls, roof, or floors) by adding insulation.
  5. Frequently clean floor and carpet :
    • Remove spots and stains immediately, using the flooring manufacturer’s recommended techniques.
    • Use care to prevent excess moisture or cleaning residue accumulation and ensure that cleaned areas are dried quickly.
    • In areas where there is perpetual moisture problem, do not install carpeting.

If you live in British Columbia and have a mould problem, contact our office at 604-435-6555. We may be able to help you or direct you to people who can help.

How Long do Mould Symptoms Typically Last?

Question: My question regards how long mould symptoms typically last. I have found what appears to be a mould growing on my window. It is gooey in texture and clear in colour. The window is often wet with condensation to the point it drips down continually for hours on end.

I am not sure if the jelly like characteristic of the mould is because of the water or because that is it’s composition. Recently the mould was disturbed by somebody in our room (they opened the window). My wife had just left the room for a while with our infant daughter (10 months) for medical reasons as this person had to come in. When she came back into the room fifteen minutes or so passed when her nose started running. Being allergic to mould she immediately told me it had been disturbed and she could smell it. She now has had for the last four days what appears to be cold like symptoms. Are these mould symptoms? What should we do? How long do mould symptoms typically last? Does my description of the mould sound at all like anything particularly dangerous? Would this be a danger to our daughter? We don’t actually have anywhere else we could live so this is important to us how we handle it. Could putting plastic window covering that seals with heat keep it from the room or would it disturb it too much? It wasn’t here in the summer but seems to have happened from the washing that we’ve hung in the room drying without any ventilation. We’re concerned for our daughter so if you could let us know asap we’d so appreciate it. As I said, we live in this room and she is in the room nearly 24 hours every day. Thank you for your time.

Answer: I haven’t found any scientific literacy that documents how long mould symptoms last. In my opinion, this could depend on the extent of damage the mould had done on an individual’s health or immune system. The extent of damage will depend on an individual’s resistant to mould exposure. Some people experience mould symptoms only when they are in a mouldy environment.

From the description you’ve given, it’s difficult to tell what type of mould it is and whether it’s dangerous or not. However, all moulds are potentially a health hazard.

Covering the mould with plastic is not a good solution since spores could still find their way into the air you’re breathing. You’ve already identified the cause of the mould growth on the window, that is, condensation due to poor ventilation and the washing that you’ve been hanging in the room.  The solution is to correct the moisture problem and to clean the existing mould. I would suggest you look for a qualified professional who could advise you on how to improve the ventilation, reduce condensation, and also how to remove the mould without spreading spores in the room. Read “ Mold Removal Guidelines ” to learn more about mould removal.

After mould removal the mould symptoms your family is experiencing are likely to disappear.

How Fast Does Mould Grow On Building Materials?

Under experimental conditions moulds are found to cover artificially inoculated building materials in 4-10 days. For example, fast growing strains of Stachybotrys chartarum produce visible mould growth on new water-damaged gypsum boards in 5 days. Slow growing strains of Stachybotrys take 14 days to completely cover the test materials. These observations suggest that visible mould growth could appear within 1-3 weeks after water damage. Under natural conditions mould growth is influenced by a number of factors.

Key factors that determine how fast mould grows

  1. Type of mould: All moulds don’t grow at the same rate. Some moulds grow faster than others. For example, under the same conditions of growth, Ulocladium would grow faster than Stachybotrys.
  2. Temperature: Moulds grow faster at or closer to their optimal temperature for growth. For most indoor moulds the optimal temperature is around 25 °C. However, mould can still grow at temperatures as low as -7 °C. Some species of Cladosporium and Penicillium are capable of growing on wood at -5 °C although spore germination requires at least 0 °C. At low temperatures mould growth is very slow.
  3. Water activity: Growth rate of mould increases with increasing water activity. Most indoor moulds have their optimal water activity at 0.96-0.98. Lowering the water activity of the material lowers the growth rate significantly. However, a few species such as some species of Aspergillus, Penicillium, Eurotium and Wallemia are able to grow at lower water activities. Germination of spores requires slightly higher water activity than the minimum required for growth.

    4. White wood-rotting fungus

  4. Age of the spores: Older spores require longer time to germinate than relatively younger spores.
  5. The spore load: If a building is full of settled viable spores, mould would cover a wider area in a shorter time, than, if there were a few settled spores.
  6. Composition of the building material: Most building materials derived from plants are highly susceptible to mould attack. For instance, wallpaper allow fast growth for cellulolytic moulds such as Chaetomium and Stachybotrys.
    • pH of the material: pH of the material strongly influences the rate of mould growth, sporulation and metabolite production. Some moulds such as Aspergillus fumigatus grow best in the pH range from 4-7 and less well at acidic and basic extremes.
    • Nutrient availability in the material: Growth could be unrestricted if all nutrients are in excess but restricted when not all nutrients are in excess.
    • Presence of antimicrobial compounds in building materials: Some building materials contain antimicrobial compounds. These compounds slow down mould growth.

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  7. Competition with other micro-organisms: In a moisture damaged environment, there is a great diversity of microorganism. These microorganisms (including bacteria) compete for nutrients and also produce by-products that may inhibit the growth of other microorganisms. Fast growing moulds tend to over-grow slow growers.

    8. Picture of black mold in basement

Conclusion

Since there are many factors that influence mould growth in buildings, it is hard to say when mould growth started. However, if we know where and when the moisture problem started, we could speculate how long the mould growth has been there.

References

  1. Nielsen, K. F. (2002). Mould growth on building materials. Secondary metabolites, mycotoxins, and biomarkers. Ph.D. Thesis. BioCentrum-DTU, Technical University of Denmark.
  2. Nielsen, K. F., Holm, G., Uttrup, L. P & Nielsen, P. A. (2004). Mould growth on building materials under low water activities. Influence of humidity and temperature on fungal growth and secondary metabolism. International Biodeterioration & Biodegredation, 54(4) 325-336

    3.  

For more information on mould growth, please visit http://www.moldbacteria.com/ or call 905-290-101.

Mould Growth In Buildings

Mould growth only occurs in moisture-damaged and damp building materials. The main causes of mould growth in buildings, therefore, may include poor maintenance and lifestyles of occupants, defective construction and use of building materials susceptible to mould attack. It is estimated that up to 40% and 30% of buildings in the USA and Canada respectively have mould problems.

Health Effects Associated With Mould Growth And Dampness

Several studies suggest that people living and working in damp or mouldy buildings have a higher risk of respiratory health problems such as asthma and bronchitis. Other symptoms associated with mould growth and dampness include blocked nose, itching eyes, and skin irritation. In agricultural environments, where the concentration of spores is several magnitudes higher than in indoor air, inhalation of spores has been associated with cancer, premature birth and farmers lung disease.

Non-viable Fungal Air Sampling Alone May Not Be Adequate

Non-viable Air Sampling

 

 

 

VersaTrap air sampling casette Air-O-Cell air sampling casette Allergenco air sampling casette

Indoor air sampling for airborne fungi is frequently conducted to assess the levels of fungal contamination and subsequently the potential risk to building occupants. It is also used to determine if there was hidden mould growth in the building or to determine the effectiveness of remediation procedures. One of the most cited advantages of non-viable air sampling is that detection of fungal structures (spores, hyphal fragments, etc) is not dependent on their viability or the suitability of agar media. Non-viable air samples are collected with samplers such as Air-O-Cell, Allergenco, VersaTrap, Burkard, Cyclex, Cyclex-d and Micro-5 among others. The spores (whether viable or dead) and other particulates are trapped on the sticky surface of the spore trap and can then be directly enumerated and identified under a microscope. Since both viable and nonviable spores can be enumerated, an efficient non-viable air sampler is expected to give a better estimate of the level of airborne fungal contamination than a viable air sampler.

Viable Air Sampling

Picture of Colony Forming Units: CFUViable air samples are often collected on agar media either in strips (if using Reuter Centrifugal Sampler) or in Petri-dishes for Andersen sampler. Unlike non-viable air sampling, detection and subsequent enumeration and identification of airborne fungal particulates collected on growth media depends on whether the spores and hyphal fragments are viable and whether the media used can support their growth into colonies. For this reason, colony counts are usually lower than spore counts. Even if all the fungal structures were viable, colony counts are likely to be lower than the spore/hyphal fragment counts because what is counted as a single colony could have developed from more than a single spore or hyphal fragment. In one study it was found that the ratios between the total fungal spores collected by the Burkard sampler and the viable fungi collected by the Andersen sampler ranged between 0.29 and 7.61.

Non-viable Air Sample

Picture of Chaetomium and Aspergillus/Penicillium sporesIs Non-viable Fungal Air Sampling Alone Adequate? In most cases viable air sampling is only used in situations where identification of the moulds to species level is required. However, our observation in the lab seems to suggest use of spore traps alone may not be adequate for airborne fungal sampling. On many occasions we have recovered moulds in viable samples that were not observed in non-viable samples even when viable and non-viable samples were taken side by side. For example Chaetomium and Stachybotrys spores, which are fairly easy to identify from spore traps have appeared in viable samples, yet, they were not detected from the non-viable samples. We have also observed that although non-viable sampling gives higher counts than viable sampling in most cases, this is not always the case. There are many factors that can contribute to these “unexpected” results.

Conclusion

Picture of Viable Air Samples On RCS Agar StripsSince both non-viable and viable air sampling have limitations, using either method singly is not adequate. To obtain conclusive information on the level of contamination and the diversity of airborne fungi in a building, taking both viable and non-viable air samples is preferable. We recommend the Calgary Health Region’s protocol, “Fungal Air Testing, Investigation and Reporting Requirements for Residential Marihuana Grow Operations (Revised May 2006)”. With few exceptions, the protocol requires that fungal air sampling consist of both viable samples (e.g. RCS or similar) and non-viable samples (e.g., Air-O-Cell) taken side by side.

References

Adhikari A., Sen M.M., Gupta-Bhattacharya S., Chanda S. (2004). Airborne viable, non-viable, and allergenic fungi in a rural agricultural area of India: A 2-year study at five outdoor sampling stations. Science of the Total Environment, 326 (1-3), pp. 123-141.

Calgary Health Region (2006). “Fungal Air Testing, Investigation and Reporting Requirements for Residential Marihuana Grow Operations (Revised May 2006)”.

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