Question: Hi there, I was hoping to get some clarity on some potential mold issues. We currently rent out a basement unit. We have never had issues before but the current tenant refuses to run the dehumidifier, as a result her wicker headboard got moldy. We had an air quality test that showed the total airborne fungal spore count for the outdoor sample was 11,000 per cubic meter and the indoor count was 43,000 per cubic meter. The testing company said they will come in and clean visible mold and that should take care of it after more indoor tests. I am just worried about spending another $600.00 and still have the same issues. Is this the correct process, should we be allowing the tenant to move back in after this 'surface' clean? Are those results worrisome? Any thoughts would be great. Thanks.




Answer: The testing company is right in suggesting a cleanup of the visible mold. However, cleaning the mold without addressing the underlying cause is a waste of resources since the mold will grow again after a few months if not weeks. The best way to control mold growth in a building is to correct moisture problems in addition to cleaning. You may get more information on mold removal at the Canadian Construction Association's website at http://www.cca-acc.com/homepage_e.asp.

Question: We live in a new home (completed Aug2006). Our house has been tested for mold and the tests have found wet plywood sheathing(>17%) and elevated levels of airborne fungal spores - in particular, the Aspergillus/Penicillium. My husband and I have both had coughs since December/2007. Should I be asking my doctor to do any specific tests? Our house was drywalled and insulated 2 months BEFORE the tarpaper and siding were installed, thus the drywall and insulation was saturated several times during the June/2006 rains. Do you have any other advice for us?


Answer: It is possible the cough is not related to mold. However, I would suggest you consult your doctor. Also, since the tests have indicated elevated levels of Aspergillus/Penicillium, you may want to hire a professional to assess the extent of mold contamination and recommend appropriate level of remediation.

Question: I have no visible signs of mold in my house... We have been living in it for 7 months and just before that the majority of the house was gutted and re-done. Recently I have had several people tell me that there is black mold in the house... on the outside specifically.  These are obviously uneducated people as I know for a fact that what they're talking about is dirt on my house from an old raised flower bed I removed. I guess my question is - what can I do to prove them wrong... I know I could probably take a sample of the dirt on the house for testing but as far as inside the house where there are no signs of mold what can I do to prove it- I just don't want this to escalate and cause a problem when we want to sell...Also how much would it cost to get a dirt sample tested for black mold.lol. I'm sorry this is just ridiculous to me. Small towns, I tell ya. Any advice you have would be greatly appreciated.


Answer: I can understand your concern. If people are seeing the dirt on the outside and they are mistaking it for black mold, I would suggest you have it cleaned up if possible. As for prospective buyers, you could have the house tested for mold by a qualified professional. Generally, where there are no signs of mould, air samples could be taken.

MBL is a leading provider of mold testing laboratory services in the Greater Toronto Area (GTA) and the rest of Canada.

As a mold and bacteria laboratory, the lab specializes in analysis of air and surface samples for:

• Bacteria testing including E.coli testing and Legionella testing, total aerobic counts
• Mold testing: Culturable Air samples such as RCS, BioCassette, Andersen, SAS, etc.
• Mold testing: Direct Microscopic Examination of tape, bulk, swab, and water samples
• Mold Testing: Spore Trap including Air-O-Cell, BioAire, and Micro5 cassettes, Allergenco, Burkard and BioSIS slides

MBL's mold and bacteria testing services are not restricted to the Greater Toronto Area (GTA). We serve clients in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, Nova Scotia and New Foundland.

MBL clients include:

• Industrial hygienists
• Environmental consultants
• Quality assurance managers
• Home Inspectors
• General contractors
• Cleaning and restoration contractors
• Property managers
• Insurance, financial, or legal professionals who deal with microbial contamination issues

For questions related to laboratory testing of samples, sampling methods, laboratory  data interpretation and other issues related to microorganisms, please call 905-290-9101 (within Toronto area) or 1-866-813-0648 if calling outside the GTA.

Mold growth is not always visible depending on the stage of growth and also whether the color of the mold itself is the same as the color of the material it’s growing on. For example, a white mold growing on a white background may not be easily visible.

Mold thrives where it’s damp. In water damaged indoor environments mold is often found on the inside of a wall cavity or on the underside of a carpet. While measuring the relative humidity in a building may indicate the potential for mold growth, the most important measurement is that of free water in the material. The “free water” is technically referred to as water activity and should not be confused with the moisture content of a material. The water activity ranges from 0 to 1.

As the water activity of organic material exceeds about 0.65, there is an increasing likelihood that mold will grow on it. Different fungi have different moisture requirements. Based on water requirements molds can be categorized as primary, secondary or tertiary colonizers.

Primary fungal colonizers

• Capable of growing at low water activity (<0.85).


• Primary colonizers prefer simple sugars.


• Primary fungal colonizers include molds such as:


• Aspergillus versicolor


• Aspergillus versicolor(25°C)


• Eurotium spp.


• Paecilomyces variotii


• Penicillium aurantiogriseum


• Penicillium brevicompactum


• Penicillium chrysogenum


• Wallemia sebi

Secondary fungal colonizers

• Require intermediate levels of water activity (0.85-0.90).


• Secondary fungal colonizers include:


• Aspergillus flavus


• Aspergillus nidulans


• Aspergillus sydowii


• Aspergillus versicolor (12°C)


• Cladosporium cladosporioides


• Cladosporium sphaerospermum


• Mucor circinelloides


• Rhizopus oryzae.

Tertiary fungal colonizers

• Require high water activity (>0.90), i.e., wet conditions. This group of fungi is generally used as indicator of moisture damage. Some tertiary colonizers, such as Chaetomium globosum and Stachybotrys chartarum prefer complex sugars (such as cellulose) or complex organics (such as wood).


• Tertiary fungal colonizers include:


• Alternaria alternata.


• Aspergillus fumigatus


• Chaetomium spp.


• Epicoccum spp.


• Exophiala spp.


• Fusarium spp.


• Mucor plumbeus


• Memnoniella echinata


• Phialophora spp.


• Phoma herbarum


• Rhizopus spp.


• Stachybotrys chartarum


• Trichoderma spp.


• Ulocladium consortiale.

Does mold contribute to respiratory disease and allergic reactions? The answer is yes. This happens when susceptible individuals inhale excessive amounts of spores and other tiny fragments of mold. Prolonged exposure to mold spores can also elicit sensitivity.

What are mold spores and how do they affect us?

• Mold spores are tiny structures produced by molds for propagation.
• Inhaled spores and mold fragments can cause allergic reactions such as runny nose and eyes, and asthma-like symptoms.
• Prolonged exposure to unusually large numbers of spores and fragments can result in the development of allergic alveolitis.
• Spores of pathogenic fungi if inhaled can infect the respiratory system and the rest of the body.

Generally there are less spores indoors than outdoors. Therefore, unless there is actively growing mold in a home the amount of mold spores present in a home are very unlikely to affect the occupants. However, in industrial environments the concentration of spores can be very high. The types of molds present in industrial environments depend on work carried out and the prevailing conditions.

Which environments are higher risks?

• Mushroom farms,
• Saw mills,
• Paper mills,
• Composting areas,
• Waste disposal sites
.
• Demolition sites,
• Agricultural environments, e.g., animal farms.

Question: I am an employee of a school that has numerous mold/bacteria issues due to water issues (pipes breaking on 4 separate occasions, as well as storm related water and roof damage when it was being constructed approximately 14 years ago. In addition to this, there have been known MAJOR HVAC issues and problems since the school was built. I as well as many others, have been battling numerous, ongoing health issues over the past 8-14 years while working in this building. An outside consulting company was finally hired (once again, due to many staff complaints) and the results are in, indicating NUMEROUS and various molds from Class A through Class C in our building. ie...Aspergillus fumigatus 4,500 CFU,
Aspergillus versicolor 15,000 CFU,
Penicillium spp 280,000 CFU,
Penicillium sp 670 CFU,
Fusarium graminearum 15,000 CFU,
Fusarium solani 9,000 CFU,
Chaetomium globosum 15,000 CFU,
Cladosporium 190,000 CFU,
Yeasts 330,000 CFU,
Rhodotorula glutinis 130,000 CFU.

The above testing was done with a dilution factor of 1000X. I have listed only 1/4 of the molds as I have yet to research the others on the list! Proper abatement guideline procedures were also not followed after each water issue and with the last water break they had working going on when we were all in the building!

As a 'lay person' your website has given me very wonderful and helpful information with regard to the numerous molds found in our building. I am glad to FINALLY understand what I know is the source of my many health issues. Given the information I have been reading, aren't the numerous types as well as the numbers above alarming? Or am I over-reacting? Should this building even be occupied? Would OSHA be the next step for me to attempt to bring awareness and get resolve? Please respond at your earliest convenience. Thanks in advance for your time :)

Answer: It's difficult for us comment without additional information on what type of samples were analyzed, how the samples were collected and the method that was used to analyze the samples.

If the samples that were analyzed were either swabs or bulk material, the numbers in the results can be very misleading and could even exaggerate the situation thus causing panic for nothing. If you could provide the complete report (without the name of your school and the company that did the testing and their addresses), we could possibly help you understand the report.

When it comes to indoor mould, it's not the numbers that you see in the report that matters (especially if these numbers are derived from bulk or swab samples!). What matters is the type of mould, the amount of mould one inhales, their body resistance and other unknown factors.


Dr. Jackson Kung'u, PhD.
Mold & Bacteria Consulting Laboratories (MBL) Inc.

During winter the dry heated air in homes and offices can irritate the nose and the throat. This irritation is reduced by use of humidifiers. However, humidifiers, if not used properly, can create perfect conditions for mould and bacterial growth. Use of humidifiers in confined areas with the doors and windows closed could result in condensation and mould growth on the walls. Mould is a recognized health hazard. Humidifier water can also support bacterial growth.

What to do:

1. Monitor the humidity level to ensure it is between 30 and 50%
2. If you must use a humidifier, buy the kind that uses steam or boiled water
3. Regularly clean the humidifier as per the manufacturer’s instructions to prevent microbial growth in the water.

• Potential health effects and symptoms associated with mold exposures include allergic reactions, asthma, and other respiratory complaints.


• There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.


• If mold is a problem in your home or school, you must clean up the mold and eliminate sources of moisture.


• Fix the source of the water problem or leak to prevent mold growth.


• Reduce indoor humidity (to 30-60% ) to decrease mold growth by: venting bathrooms, dryers, and other moisture-generating sources to the outside; using air conditioners and de-humidifiers; increasing ventilation; and using exhaust fans whenever cooking, dishwashing, and cleaning.


• Clean and dry any damp or wet building materials and furnishings within 24-48 hours to prevent mold growth.


• Clean mold off hard surfaces with water and detergent, and dry completely. Absorbent materials such as ceiling tiles, that are moldy, may need to be replaced.


• Prevent condensation: Reduce the potential for condensation on cold surfaces (i.e., windows, piping, exterior walls, roof, or floors) by adding insulation.


• In areas where there is a perpetual moisture problem, do not install carpeting (i.e., by drinking fountains, by classroom sinks, or on concrete floors with leaks or frequent condensation).


• Molds can be found almost anywhere; they can grow on virtually any substance, providing moisture is present. There are molds that can grow on wood, paper, carpet, and foods.

Source: US, Environmental Protection Agency

Many homeowners often ask us if there is a way they could test for mold themselves in their homes. Although we recommend seeking professional help there are some simple tests that a homeowner can perform if mold growth is not extensive.



Testing For Visible Mold Growth Using Clear Scotch Tape

Clear scotch tape can be used to sample visible mold.

• Cut 2-3 inches of the tape and press it gently onto the surface with visible mold growth.


• Peel the tape off the surface and stick it onto a plastic bag (e.g., ziplock bag)


• Put the sample into an envelope and then send to Mold & Bacteria Laboratories for identification. For $45 per sample the laboratory will tell you the type of mold present on the sample and whether it is a type considered to be of health concern. If you are sure the mold covers less than 10 square feet, you can clean it yourself (with proper protection) after fixing the moisture/water source. For large amounts of mold growth, we recommended you seek professional help. For detailed instructions on how to take tape samples download the document Homeowner Form.

Testing For Airborne Mold Using Agar Settle Plates

If you can't see mold but have persistent musty or earthy smell, you may consider testing the air for mold. Musty or earthy smell is often an indication of microbial growth such as mold and some type of bacteria. A homeowner can perform preliminary tests using agar settle plates before calling a professional. Download the document "Air sampling for mold using agar settle plates" for detailed instructions on how to perform this test. You can obtain the agar settle plates from Mold & Bacteria Consulting Laboratories.

Recently we received the email below and the sender agreed we could share it with our readers. Here, we're talking of the agony of living in a moldy house.

"Dear Dr. Kung'u:
An article of yours was recently posted on a listserv in the States to which I belong, and I am curious about your work. Several years ago now, I lived in a building which had a sewer pipe leak beneath it go untended long enough for the water to soak up into the structure of the building and cause a great outgrowth of mold in the wood floors beneath the carpeting in the unit below mine. Mold was first seen growing up the walls and on clothes in picture frames and on items in the closet.

Several of us in this small building had bizarre neurological problems with balance and seizures, but it took us awhile to connect the dots to exposure to neurotoxins resulting from the leak under the building. When my downstairs neighbor was diagnosed as having asthma and allergies from his mold exposure, we moved from the building.

Unfortunately for my neighbor downstairs, it was not soon enough - he died three months later after producing quantities of foam and blood from his mouth. I've been working with his mother since that time, and we have finally proved that he had Trichothecene mycotoxicosis. We don't yet have quite all the information we need to prove causation for court. We haven't been able to tie the Trichothecene to a particular mold found there by means of DNA, however, there were several molds present in an earlier air sampling that can produce Trichothecene.

Since it was a sewer leak, we know bacteria was involved, although the sampling we've had done hasn't tested for bacteria, and we don't really know what we need to know about what role it played in our human tragedy. Is there a good primer anywhere to read up on what to test for and how that is done? Do you do that sort of work in the U.S.?

Thank you,"

What is toxic mold? Strictly speaking there is no toxic mold. The correct term is "Toxigenic Mold". Toxigenic molds refer to those molds that produce byproducts toxic to humans and animals. These byproducts (secondary metabolites) are referred to as mycotoxins. Not every mold is toxigenic. It is good to know toxigenic molds do not produce mycotoxins all the time. However, since it is difficult to tell when mycotoxins are produced (unless a test is performed) food or feed contaminated with mold should never be consumed.

When you suspect a mold problem in your home, you don't want to risk your health by trying to clean the mold yourself unless you're sure of what you're doing. Also, if you are buying a home, you want to be sure the home you buy is not contaminated with mold. There are many companies in Ontario that provide mold testing and removal services. You can find a listing of mold testing and mold remediation companies or professionals operating in Ontario by clicking Mold Testing and Removal Companies In Ontario. We know the listing is not exhaustive since we have only listed those companies that requested to be listed. It is up to the user to find out the credibility of the company they decide to hire.

Mold in houses is a health hazard, it's unsightly and also damages materials on which it is growing on. In houses mold can be found growing on walls, ceiling tiles, clothes, shoes, books, foodstuffs, and other valuable items.

What Is The Source Of Mold In Houses?

Mold in houses originates from outside environment in form of airborne spores and fragments. Outside the house, the molds grow on dead plant material (a few of these moulds are also capable of growing on living plants causing diseases) and produce spores which become airborne. The concentration of spores in the outside air reaches peak levels in summer. When we open our doors or windows, the spores and other mold fragments are blown into our houses by wind and settle on various surfaces. If the surface on which the spore has settled become wet, the spores germinate and if the material is organic such as paper, leather, and wood the germinated spores continues to develop into visible mold growth which in turn produces mores spores.

A number of molds are also soil borne. These can be carried into houses by flood water or soiled shoes, implements or other articles.

Frequent vacuum cleaning reduces spore load in houses.