Toxic Mold & Disease

J.L. Laurence

Asthma has increased 600 percent in children in the past ten years. Research by WHO (World Health Organization) in Germany, finds prostate cancer, breast cancer, and other cancers increasing due to mold-related problems.

Mold is the number one health problem with one in every three persons affected by mold and one in ten with a severe problem related to mold. These can range from the common cold, tonsillitis, otitis, sinusitis, bronchitis, asthma, MS and pneumonia, to cancer.
Check your home's humidity levels; buy or borrow a hygrometer and watch the changes in R.H. that occur throughout a typical day in different rooms of the house and over the heating season. To inspect your home for mold growth, winter is the best time except for basements which should also be inspected in the summer. With a flashlight and some simple tools, go through the entire house, both inside and outside, searching for moisture damage and mold growth and their potential causes.

The Stachybotrys species of mold is dangerous; it will start growing in 80 percent humidity but, once established, can grow at 55 percent humidity. This mold can develop from the decay of building materials and is much harder to control. If more than ten square feet develop, it is advised that a professional clean it up. When you see a small speck of mold, that's only part of the problem - the remainder being inside the walls.

'Frog Page' is a manual of the health of the environment and states that frogs are declining because of mold. 

Some of the causes of mold are brush and trees within 30 feet of the building; venting the clothes drier inside the home; furniture against outside walls; old fill, causing building movement leading to cracks causing water ingress; concrete will wick up water even to several feet above ground; ventilation not directed outside, such as the kitchen range hood, which should be vented outside; plants and aquariums; drying clothing indoors; standing water, such as keeping cold water in the kitchen sink; hot tubs; using several gallons of water to wash floors.

'Sick Building Syndrome' is caused by moisture and mold growth. It migrates through foundations up from the soil. A dehumidifier is not the final answer as it only does the air and not the walls. What is required is a combination of ventilation, circulation, and heat.

Carpenter ants and termites will smell moisture from miles away and they only attack damaged wood. Ventilation alone won't help a crawl space. In the summer the vents bring in warm, moist air. Mold forms on the coldest space. The only way to deal with it is with heat. Wall heaters with fans are more efficient than baseboard heaters.

Pull furniture and store material away from exterior walls and off basement floors; leave closet doors ajar; leave bedroom doors open as much as possible; undercut doors; don't block or deflect warm air registers; open drapes, blinds, and curtains; set the furnace fan to run continuously. This will use more electricity but can be offset by installing a two-speed energy-efficient motor; don't cut off the heating supply or close off unused rooms.

Uninsulated or poorly insulated areas such as exterior corners or foundation walls, should be improved with additional insulation. Be sure to install an air-vapor barrier, usually polyethylene, on the room side of the insulation to prevent hidden condensation behind the insulation. Seal hidden opening into the attic, tighten the attic hatch, weatherstrip and caulk around windows and doors, gasket electrical outlets, caulk baseboards and seal the top of foundations. Using an air conditioner on muggy summer days also helps take out the moisture.

Humidifiers, dehumidifiers, air-conditioning units and filtration systems can be a source of mold growth if they are not regularly cleaned and maintained.

Key areas to check for moisture sources leading to condensation inside the home are roof leaks [especially at chimneys, flashings, skylights and eavestroughing]; wall leaks [especially at window and door flashing and sills]; foundation leaks [especially where the ground slopes toward the foundation]; and plumbing leaks [especially at toilet bases and under sink drains].

Check any fuel-burning equipment - furnaces, hot water heaters, boilers, fireplaces, and wood stoves - to ensure that they are venting properly. A blocked chimney could mean that combustion products, including large amounts of water vapor, are spilling into your house. Along with that moisture come dangerous combustion gasses, such as carbon monoxide, which cause deaths every year. Have heating equipment and venting systems checked by a trained service person.

If your moisture remedial work includes extensive air sealing, be sure that all fuel-burning equipment has an adequate supply of combustion air. High efficiency furnaces, for example, have their own air supplies and exhaust fans but conventional equipment may rely on house air for combustion and on 'natural draft' to move combustion products up the chimney flue. If starved for air or overpowered by an exhaust fan somewhere else in the house, such equipment can spill combustion gasses indoors. Examples of this include stains near the vent of a gas water heater, smoke entering the room from a wood-burning fireplace or stove, and pilot lights being blown out.

Mold growth often occurs in out-of-the-way areas like closets, corners, walls behind furniture and unused rooms. Increasing air circulation to these areas warms the cold surfaces and lowers local humidity levels.

To solve moisture problems, cover any exposed earth in a crawl space or basement with heavy polyethylene, sealed and weighted-down; slope soil away from foundations to keep basement walls and slab dry; patch any foundation leaks; don't use humidifiers, unless humidity levels are below 30 percent R.H.; avoid drying firewood indoors; operate bathroom exhaust fans during a bath or shower; use your range hood exhaust when cooking; avoid steam-cleaning carpets in winter; clean mold from wood and gyproc with a 10 percent to 30 percent solution of hydrogen peroxide applied with a spray bottle. This is more effective than bleach and water.

If you use chlorine bleach, mix one part bleach with two parts water and a little detergent to clean nearby surfaces. Leave for 15 minutes and rinse well. Use gloves, protective glasses and a tight-fitting dust mask, along with good ventilation. Persons with any respiratory problems should not perform clean-up or be in the clean-up area. Children and pets should not be allowed access. Soiled curtains, clothing, linens and any other washable materials should be removed and cleaned. Badly mildewed carpets, furnishings and books will probably need to be thrown out.

Molds are parasitic micro-organisms that appear as black, white or multi-colored stain or fuzz. In addition to causing asthma, they can cause other allergies and serious health problems. There are tens of thousand of varieties of molds and are difficult and expensive to identify, even for experts. Health officials recommend eliminating all molds from inside your home.

Most mold spores need condensation or damp materials to germinate and once are established, many colonies generate their own moisture and can continue to survive even under dry conditions. They also need mild temperatures and a source of food, such as house dust or drywall paper.


1. Natural Resources Canada [NRCan] "Air-Leakage Control" Pg. 11 [20 Feb 2002]

2.WHO [World Health Organization] [20 Feb. 2002]
3.Cormier, Dr. Y., Centre de Recherche, Hopital Laval, 2725 Chemin Ste-Foy, Ste Foy, Quebec Canada, G1V-4G5, Institut de Recherche en Sante et Securite du Travail (IRSST), Quebec Canada, July 21, 1999; revised; accepted for publication November 26, 1999.
4. [20 Feb. 2002]

5. [20 Feb.2002]

[20 Feb. 2002]

[Return to menu]