L'Association pour la santé environnementale du Québec / Environmental Health Association of Québec

How to Manage – Mould

About Mould

Mould has always been with us; it can be found just about everywhere. Basically, where there is life, there is mould.

Problems arise when concentrations of mould grow in contained spaces, such as our homes, or when we live in very humid areas.

The Canadian Mortgage and Housing Corporation (CMHC) estimates that more than 60+% of finished basements have mould in their drywall. They also found that about 40% of the mould in these basements is toxic, which means if you have a finished basement, your chances of having unhealthy mould in your house are greater than 25%.

Mould grows in humidity levels above 70%. Buy a hygrometer at your local hardware store, and use it to measure humidity levels. Humidity should be between 30% and 55%, closer to 30 in the winter. Remember that a reading in the middle of the room may be lower than one taken near a window or behind furniture. Increase ventilation or use a dehumidifier to get rid of excess humidity, but make sure to clean it regularly to prevent mould growth. Do not place heavy furniture against an outside wall.

Make sure the home is properly drained. Gutters and down spouts should drain away from the home, and soil should be graded away from the home.

There are thousands of species of mould, which come in several shapes and colours. Some are allergens, others can sensitize you, and still others produce toxins, which can be very dangerous. Stachybotris, a black mould, is by far the most toxic to human health. There are other black moulds, so just being black does not mean it is Stachybotris.

The following are some of the symptoms people can experience due to exposure to mould:

  • Sneezing
  • Runny or stuffy nose
  • Cough and post nasal drip
  • Itchy eyes, nose and throat
  • Watery eyes
  • Dry, scaly skin
  • Coughing
  • Wheezing
  • Shortness of breath
  • Chest tightness

Source : Mayo Clinic

Your blood can be tested for mycotoxins or for antibodies to several species of mould. It is sometimes difficult to connect symptoms to a mould exposure, since symptoms can vary and be intermittent, because mould can give off different toxins at different times of day and at different temperatures.

Mould needs moisture and humidity in which to grow, although some species continue to produce spores even when dry. These spores attach to the dust in your environment and can contaminate your whole house. They grow on cellulose, which means mattresses, stuffed items, books, paper, drywall and insulation are favourite places for them to grow. Anytime you notice visible signs of mould, you can be sure there is much more than the eye can see.

Mould will begin to grow on a damp surface within 24 to 48 hours. Therefore, any leak or water damage must be opened up and thoroughly dried within 48 hours, if you want to prevent mould growth.

Is there mould in my home?

If you suspect the presence of mould, you may need to call in a reputable professional who can inspect and test the air quality in your home. Cultures can be taken from a petri dish or from the dust in your home. Some experts contend that dust sampling is more accurate. This will tell you whether you

have an unacceptable level of mould in your home’s indoor air. An inspection with a device that measures humidity in the walls will indicate where the problem might be. Professionals also have miniature cameras that allow them to spot hidden mould inside walls, or infrared cameras, which can indicate temperature changes and where water/air may be infiltrating a home. There are also dogs trained to detect the presence of mould.

Once you have located the problem, all visible wet and mouldy material, as well as a larger area where mould may have begun to grow, must be removed. This must be done by a professional who will ensure that the area is properly contained so that spores will not be released into the rest of the house.

Once the source has been removed, you must proceed with a ‘spring cleaning,’ washing as many items as possible in hot water, putting stuffed items such as mattresses and sofas out in the sun, and washing walls and ceiling as well as every horizontal surface in the house with a damp cloth and a little unscented soap, then rinsing once again with a wrung-out cloth. Do not use bleach when cleaning mould, as it will encourage the mould to release spores or mycotoxins. Also, bleach is toxic. If the contamination has been extensive, you must proceed with a second air quality test after six months. Never let any professional apply a fungicide inside your walls especially if you have environmental sensitivities. Removing the source completely is generally sufficient. Food grade hydrogen peroxide may be used if you absolutely want to put something in the wall.