Mould

Moulds are fungi that can be found both outdoors and indoors. Typically found in nature, they are necessary for the breakdown of leaves, wood and other plant debris. Moulds can enter your home directly or through spores in the air through open doorways, windows, vents, and heating and air conditioning systems, clothing, shoes, and pets.

When mold spores drop on places where there is excessive moisture, such as where leakage may have occurred in roofs, pipes, walls, plant pots, or where there has been flooding, they will grow.

Many building materials provide suitable nutrients that encourage mold to grow, including paper and paper products, cardboard, ceiling tiles, wood, and wood products, drywall, carpet, fabric, and upholstery.

Look for common signs of mould in your home:

• Discolouration: mould can be any colour: black, white, red, orange, yellow, blue, violet, etc.
• Signs of excessive moisture: water stains, condensation on surfaces, flooding of an area, high humidity in the home
• Odour: a musty or earthy smell may be present

The presence of mould does not always means that health problems will occur. Health risks depend greatly on exposure and each person’s sensitivity. Exposure to damp and moldy environments may cause a variety of health effects, or none at all.

People living in homes with mould and damp conditions are more likely to have:

• eye, nose and throat irritation
• coughing and phlegm build-up
• wheezing and shortness of breath
• worsening of asthma symptoms

Some people are more susceptible than others, including infants, children, the elderly and those with existing health problems such as breathing difficulties. The level of concern depends on the extent of mould, how long it has been present and the sensitivity and overall health of the residents. 

Any respiratory health concerns should be discussed with a physician. If you suspect that these could be caused by poor indoor air quality, a physician is best suited to determine if your symptoms may be related to environmental factors or some other underlying cause.

Health Canada does not recommend testing the air for mould.

• An air test does not provide information on health and does not address the cause of mould damage in the house
• You do not need to know the type of mould present in order to remove it: all moulds should be treated the same in terms of health risk and removal
• Mould is a natural part of the environment. There are always some mould spores in air. Simply finding mould spores in an air test does not necessarily mean there is a problem

The best way to reduce your health risk from mould is to clean up the mould and identify and remove the moisture sources to prevent further growth.

Since moulds need moisture to grow, removing sources of excessive moisture are the best way to prevent mould growth. Unless the cause of the moisture problem has been identified and solved, mould will reappear. Moisture problems are preventable. Clean mold as you see it and investigate the source of moisture allowing it to grow.

Common sources of moisture problems in homes:

• daily activities such as showering or bathing, or cooking can lead to excess moisture if exhaust fans are not used
• water from outside can enter cracks or leaks in the foundation, floor, walls or roof
• plumbing leaks
• moisture condensation on cold surfaces
• flooding due to weather conditions (snow melt, storm surges, heavy rainfall)
• poor air flow in the home

Prevent excess moisture by:

• Ensure water drains away from the house by sloping the grade away from the building
• Keep eavestroughs and downspouts clean of debris and that they drain away from the house
• Repair plumbing leaks
• Use exhaust fans, ventilation and air conditioning systems to vent moisture outdoors
• Run a dehumidifier in damp areas such as basements

Small and medium mould areas can be cleaned yourself. Health Canada does not recommend that an unqualified person clean up large areas of mould. To prevent the spread of mould clean areas with visible mould as soon as possible once noticed. Do not paint over visible mould. Painting over a mouldy surface will not kill mould and des not stop it from growing back, it just hides the problem.

• Small area: 3 of less patches of mould with a total area of less than 1 square meter
• Medium area: more than 3 patches of mould between 1 and 3 square meters
• Large area: a single patch is greater than 3 square meters

What you need to clean up small/medium areas of mould?

• Safety glasses
• A disposable dust mask (N95)
• Gloves
• Soap and water (Bleach is not recommended for cleaning up mould)

Instructions: 

1. Clean washable surfaces with soap and water and dry quickly by opening windows, use of fans and use of a dehumidifier.
2. Add baking soda to the mixture when cleaning drywall and clean the surface with a damp cloth. Cleaning drywall with too much water can add moisture to drywall and damage the surface.
3. Dispose of soiled cleaning materials immediately.
4. Dispose of any items damaged by moisture or mould that cannot be cleaned.
5. Find and fix the source of moisture that is allowing the mould to grow

• Health Canada: Addressing Moisture and Mould in Your Home
• Health Canada: Mould
• Canadian Mortgage and Housing Corporation: Mould in Housing
• Canadian Centre for Occupational Health and Safety: Indoor Air Quality
• Tribunals Ontario