Mould Remediation Information Sheet

Concerns over indoor air quality and healthy building environments have focused public attention on the adverse health effects associated with exposure to mould.

Moulds are a form of fungus, and they are essential to the natural ecological system.

Moulds help decompose organic matter. There are thousands of species of mould, any of which have not yet been identified. Over a thousand different species of mould are found in Canada and the United States. As part of their reproductive process, many species of moulds produce and broadcast microscopic spores that are capable of spreading to new locations through the air, and will grow on virtually any organic substance if there is a source of water, and oxygen. Although moulds occur naturally, there is a concern when they start to grow in a building environment. Microscopic mould spores and fragments that become airborne in a building environment can be inhaled into the respiratory system and are suspected of causing a variety of adverse health problems.

Many species of moulds are thought to be relatively harmless to humans; however, some moulds are known to produce spores containing allergens which can cause allergic reactions particularly for people with asthma, bronchitis, hay fever, or allergies. Symptoms such as runny nose, eye irritation, skin rash, cough, and congestion are the most common complaints. Other species of moulds produce spores containing potent toxins known as mycotoxins. One species of mould stachybotrys chartarum, (also known as stachbotrys atra) is probably the most studied, and is being investigated as the cause of a sometimes fatal pulmonary haemorrhage (bleeding of the lungs) in infants. Mould exposure seems to affect individuals differently, and to varying degrees, depending on the species of mould, the level and duration of exposure, and the susceptibility of the person exposed. Reactions from mould exposure can range from mild allergic reactions to severe respiratory infections.

Mould can grow in almost any building, spores may enter through open doorways, windows, and air handling systems, or be tracked in on peoples clothing and shoes. When mould spores land on an appropriate organic surface with sufficient moisture they will grow.

Mould growth in buildings is compounded by the fact that many of our modern building products are cellulose based and will readily support mould growth. Cellulose building products like cardboard, ceiling tiles, wood products, and the paper layer on gypsum board, are particularly inviting to some species of moulds including stachybotrys.

Moulds require moisture to grow, and many moisture problems in buildings are the result of contemporary building construction practices. Energy conservation programs and the corresponding building designs have resulted in a great many buildings that lack adequate ventilation which can lead to an accumulation of moisture in the building environment. Moisture problems also occur as the result of condensation, roof leaks, and other water intrusions. Buildings that have been flooded as a result of plumbing leaks, sewage leaks, or fire suppression are especially vulnerable to mould growth. Since mould requires moisture to grow, the key to preventing mould growth in a building is to control the moisture.

Detecting a mould problem in a building can sometimes be as simple as observing a visible mould growth, or as complicated as investigating crawl spaces, attics, wall cavities, and other concealed locations. Destructive investigations are sometimes required in order to investigate beneath flooring materials, or inside wall and ceiling cavities. Professional help is recommended.

The most effective way to remediate mould growth is to correct the accumulation of moisture, and thoroughly clean the affected area using appropriate remediation techniques. Porous materials that are not easily cleaned may have to be discarded. Personnel performing mould remediation should be specifically trained in remediation procedures in order to avoid exposing themselves or building occupants to airborne mould laden dust. Extreme caution should be used to prevent mould dust from being dispersed throughout the building environment, which could expose building occupants, and propagate mould growth in other areas of the building. Respiratory protection, protective clothing, and work area isolation or containment is required to protect the workers, and prevent adjacent areas of the building from becoming contaminated. Large scale mould remediation projects should only be attempted by trained professionals.