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.

Stachybotrys – The Black Mold Demystified

Since the 1993-1994 unusual outbreak of pulmonary hemorrhage (lung breeding) in infants in Cleveland, Ohio, that was then thought to be due to  exposure to Stachybotrys, the health effects associated with this mold have remained controversial. Frequently referred to as the Black Mold by the general public, Stachybotrys has probably caused more economic and psychological agony than ill-health. The mold has resulted in multimillion dollar remediations and litigations.

Stachybotrys was first associated with death of horses in Eastern Europe in the 1930s. Horses fed with hay contaminated with Stachybotrys were reported to surfer from a disease characherized by irritation of the mouth, throat, and nose; shock; dermal necrosis; a decrease in leukocytes; hemorrhage; nervous disorder; and death.

While Stachybotrys is so much feared the number of cases where it was the cause of ill-health or death are insignificant compared to some other toxigenic molds such as Aspergillus flavus or Aspergillus fumigatus. There are about 15 species of Stachybotrys but the most well known is Stachybotrys chartarumStachybotrys chartarum is sometimes erroneously referred to as pathogenic mold. When encountered in buildings it’s a serious problem for homeowners, building managers and remediation contractors who must deal with the human issues and remediation. The presence of a single spore in an air sample is enough for some professionals to declare the remediated building unfit for human occupancy. Currently there is no scientific evidence to support such a decision. Perhaps such decisions are driven by fear of liability, fear of being sued by someone who may later believe they were sick because the building was found to have a few spores of Stachybotrys when they occupied it. It’s time the scientific community demystified Stachybotrys, the black mold, for everyone’s peace of mind.

Should you have a question on Stachybotrys please contact us at 905-290-9101 in Ontario or 604-435-6555 in British Columbia.


1. Stachybotrys chartarum: The Toxic Indoor Mold.

2. Indoor Mold, Toxigenic Fungi, and Stachybotrys chartarum: Infectious Disease Perspective.

Health Effects of Mold

All molds are potentially a health hazard. While majority of common molds are not a concern to individuals who are healthy, the health effects of most of the indoor molds are not known. Some symptoms associated with mold exposure are also highly controversial. Health effects of mold include:

1. infection;

2. allergic reactions (i.e., allergy);

3. mycotoxin poisoning.


Infection of healthy individuals by indoor molds is very rare. Occasionally, however, immunocompromised individuals may be infected by some opportunistic pathogens such as species of Aspergillus, Penicillium and Fusarium.

Allergic Reaction

It’s estimated that about 20% of the human population is allergic to normal spore concentrations. The rest 80% would require exposure to higher spore concentrations. Health effects of mold partly depends on the amount of mold an individual is exposed to. However, with the large number of mold species and strains growing in buildings and the large inter-individual variability in human response to mold exposure it’s hard to define what is “normal” or “high” mold spore concentration.


Apart from infections the most well known health effects of mold is mycotoxin poisoning. Some common molds such as Aspergillus flavus, Stachybotrys chartarum, Fusarium, Alternaria, Paecilomyces, Rhizopus, Trichoderma, and Trichothecium produce substances (mycotoxins) that are toxic to humans, animals or other microorganisms. A number of mycotoxins are not only toxic but are also highly potent carcinogens. Spores of toxin producing molds contain mycotoxins. Majority of mycotoxins are not volatile and therefore mycotoxin exposure is likely to occur through inhalation of spores and dust. Evidence that inhaled mycotoxins affects human health is circumstantial.

Minimizing Exposure To Mold

The best way to deal with the health effects of mold is to minimize exposure to mold. Exposure to mold can be minimized by improving the indoor air quality. Here are some steps one can take:

  • Controlling humidity and letting more air into the house by ensuring sufficient ventilation. This prevents moisture from building up on walls and windows. If there is excessive humidity, mechanical ventilation such as a fan may be needed to get rid of it.
  • Measuring humidity by using a hygrometer to see if a de-humidifier is needed. The relative humidity should be kept below 50% in summer and 30% in winter.
  • Repairing leaky roofs, walls, and basements.
  • Cleaning moldy surfaces with a detergent.
  • Keeping the house clean and dust-free.
  • Regularly cleaning and disinfect humidifiers, de-humidifiers, and air conditioners.

If you have a question regarding health effects of mold, contact us at 905-290-9101.

Black Mold Symptoms Explained

The phrase “black mold symptoms” is one of the most searched phrases regarding health effects of mold. The general public believes that black mold is dangerous. However, the term “black mold” does not refer to a specific type of mold. Similarly there are no symptoms specific to “black mold”. A number of molds that grow indoors may appear black. Generally all molds regardless of their color are potentially a health hazard if allowed to grow indoors.

Symptoms of Mold Exposure

The term “black mold symptoms” is rather misleading. People who are sensitive to molds, regardless of the color of the mold, may experience various symptoms such as nasal stuffiness, eye irritation, wheezing, or skin irritation. Those with serious allergies to molds, may have more severe reactions. Severe reactions may occur among workers exposed to large amounts of molds in occupational settings, such as farmers working around moldy hay, demolition workers tearing down a moldy building, and even people working near or in composting facilities. Severe reactions may include fever and shortness of breath. People with chronic lung illnesses, such as obstructive lung disease, may develop mold infections in their lungs.

These symptoms are not restricted to mold exposure. They could also be caused by other airborne polutants. Therefore, the fact that someone is experiencing these symptoms does not necessarily mean they are caused by mold exposure. It’s also important to remember there are no “black mold symptoms” and “black mold” could be any of the several types of molds that appear black.