Dr Jackson Kung'u- Mold Specialist

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Dr. Jackson Kung’u (PhD)- Mold Specialist.
Phone: 905-290-9101
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Home | 2011 | October 2011

Archives for October 2011

Air Quality Test Showed No Mold But Can See Visible Mold

Air quality test is often conducted to determine the level of airborne mold spores. Interpretation of air quality test results is often difficult as the levels of mold spores in the air vary greatly depending on the activity in the room, changes in temperature and relative humidity, ventilation rate and season of the year. During summer for example, indoor mold spore counts can be relatively very high even in homes with no visible mold growth due to infiltration of spores from outdoors.

It’s also possible to have very few airborne spores in buildings with visible mold growth. This is because there are biological differences between the fungi in terms of the way they produce their spores. The Aspergilli and Penicillia, for example, produce large quantities of dry spores that easily become airborne. On the other hand, Fusarium and some species of Stachybotrys (black mold) produce moist spores that are not easily released into the air. Some other molds such as Chaetomium and Phoma produce their spores in enclosed structures (fruiting bodies) and hence these spores may not be detected by air sampling until later when the material dries out or is broken on impact e.g., during renovation.

For viable samples, the spores and fungal materials present in the air may be dead or may belong to molds that cannot be cultured in artificial media. The mold may also be alive but may not be culturable on the detection media used. Therefore a combination of air sampling (both viable and non-viable), surface (e.g., tape-lift) and bulk sampling is recommended. An air quality test alone is not enough to rule out mold growth. See the article Non-viable Fungal Air Sampling Alone May Not Be Adequate.

Mold Exposure: Symptoms of Mold Allergy

Mold exposure does not always present a health problem indoors. However some people (about 20% of the human population) are sensitive to molds.  Symptoms of mold exposure are primarily allergic reactions involving the upper respiratory system. Also referred to as mold allergy, the symptoms can include:

  • Sneezing
  • Runny or stuffy nose
  • Cough and postnasal drip
  • Itchy eyes, nose and throat
  • Watery eyes.

Symptoms of mold exposure vary from individual to individual, and range from mild to severe. Some individuals may have year-round symptoms or symptoms that flare up only during certain times of the year when the allergens are present. Currently no exposure limits have been established. The large number of mold species and strains present in the environment and the large inter-individual variability in human response to mold exposure make it difficult to establish exposure limits.

For individuals with mold allergy and asthma, their asthma symptoms may be triggered by exposure to mold spores. In some people, exposure to certain molds can cause a severe asthma attack. Signs and symptoms of asthma include:

  • Coughing
  • Wheezing
  • Shortness of breath
  • Chest tightness.

On some rare occasions, effects of mold exposure may include infections and toxic effects. Serious infections from living molds are relatively rare and occur mainly in people with severely compromised immune system. Many types of molds may produce toxins but only under certain growth conditions. Toxic effects have been reported from eating moldy grain, but evidence is weak that inhaling mold spores in buildings causes toxic effects.

Prevention of mold exposure and ensuing health issues include control of mold growth in the first place by rectifying the moisture problems. Failure to completely dry out building materials after extensive flooding and water damage can result in extensive mold growth.

If you are concerned about mold exposure, check your home to make sure there are no hidden areas of mold growth. Speak to your doctor if you have had previous mold exposure, and discuss any symptoms you may be experiencing.

Indoor Air Quality – Testing For Mold

The health effects of poor indoor air quality are dependent upon several factors including the type of contaminant, concentration, duration of exposure, and individual susceptibility. Indoor air quality can be compromised by a number of contaminants including mold.

Assessing the status of Indoor Air Quality

The status of indoor air quality is assessed by measuring the levels of contaminants indoors. These Contaminants include:
1. Biological contaminants such as mold, bacteria, viruses, etc.
2. Chemical contaminants such as formaldehyde.

This article is focusing on mold as an indoor air contaminant. Contamination of air by mold spores can easily be determined by air testing.

Testing Air for Mold

There are two methods commonly used to test air for mold. These are:
1. Viable or culturing air testing

2. Non-viable or total spore count air testing.

Assessing the Status of Indoor Air Quality by Viable Air Testing.

For viable air testing, air sampling can be conducted in two ways. The first method uses settle plates. This technique involves opening agar plates inside the area being tested and leaving them open for half an hour or more. Airborne mold spores and hyphal fragments settle by gravity onto the agar plates. Any viable spores or hyphal fragments would then grow into visible colonies that can be counted and identified. A high colony count is an indication of poor indoor air quality. This method is cheap since all it requires is agar plates. However, it’s not an efficient way of testing for mold spores in the air. The second method uses an air sampling pump. In this case, air is impacted onto the agar plates by a pump. This method is more efficient since it doesn’t depend on free-falling of spores into the agar. Viable testing for mold has a big disadvantage in that it only detects viable spores/hyphal fragments yet even dead spores are a health hazard.

Assessing the status of Indoor Air Quality by Non-viable Air Testing.

Non-viable air testing samples are collected by impacting air on an inert surface coated with an adhesive. Most of the spores and other particulate in air get stuck on the adhesive surface. The samples are then tested by direct microscopy. The spores and/or other particulates are enumerated and identified. The results are reported as spores per cubic meter of air. This method of sampling requires an air sampling pump such as BioPump and air sampling cassettes such as Air-O-Cell or allergencos. The major advantage of this method is that both viable and non-viable airborne spores and other particulates are enumerated thus giving us a better idea of the status of the indoor air quality.