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Moulds are found everywhere in our environment. Learn about how to recognize mould in your home and how to get rid of and prevent new mould growth.

Mould is a common household problem. Even everyday activities which create moisture such as bathing, cleaning and cooking can lead to mould growth in your home.

What are moulds and where do they come from?

Moulds are microscopic members of the fungus family, found everywhere in our environment. Mould plays an important role in our outdoor environment, helping to decompose organic matter such as leaves and wood. As mould grows it produces:

  • Mycelium – a network of fine white filaments that can become visible to the human eye
  • Spores – seeds that can travel through the air to land elsewhere

Spores regularly enter the home through open windows and doors, clothing, pets, food, and furniture.


What does mould need to grow?

Water and food are the two essential conditions for mould to grow. Mould can become established in as little as 48 hours!

Certain types of mould require an extremely wet environment, while others require far less moisture to grow. Moisture resulting from any of the following problems can invite mould into your home:

  • Water leaking in from outside (from roof, walls or floor)
  • Plumbing leaks
  • Normal activities that use water such as bathing, washing clothes or cooking
  • Condensation on or within walls or floors

Are moulds a health hazard?

Most types of moulds found in homes and buildings are not a health concern for healthy people. While some health problems are a result of exposure to mould, others are more difficult to prove. Health effects depend on the:

  • Type of mould
  • Amount of mould
  • Production of certain substances by the mould
  • Degree of exposure
  • Health condition of the person exposed

Pregnant women, infants, the elderly, and those with weakened immune systems are more at risk of health problems when exposed to mould.


What are the health effects of mould exposure?

Allergies to mould may develop in up to 5% of the population.

For sensitive individuals, allergic symptoms can include:

  • Sneezing
  • Runny nose, congestion
  • Red, watery eyes
  • Skin rash
  • Increase in existing asthma symptoms

Other health effects of mould:

  • Irritation of the eyes, skin, nose, throat, and lungs
  • Skin infections such as athlete's foot or jock itch ( not associated with mould growth in homes)
  • Severe infections in people with weakened immune systems ( not associated with mould growth in homes)

Once removed from the environment, allergies and irritation should disappear. Consult with your family doctor if you think you suffer from health effects due to mould exposure.


How do you prevent mould?

While we cannot eliminate mould from our environments completely, there are a number of ways to prevent mould growth in your home.

  • Check your home regularly for signs of moisture and mould.
  • Fix any water leaks, moisture or condensation problems promptly.
  • If water gets into your home, dry the area within 48 hours to prevent growth.
  • Ensure sufficient ventilation in moisture heavy rooms such as bathrooms or kitchens. Fans and clothes dryers should exhaust to the outside of the home.
  • If necessary, use a dehumidifier to lower the relative humidity (below 60%, ideally 30-50%).
  • Reduce the amount of stored materials. Moulds grow on fabrics, paper, wood and anything that collects dust and holds moisture.

Should you get professional help to clean up mould growth?

Whether you should clean the area yourself depends on the size of the mould growth.

  • Small areas (< 1 square meter in overall size)
    A project manageable by homeowners. Be sure to follow proper procedures.
  • Large areas (> 1 square meter in overall size)
    The Health Department recommends calling a professional experienced in mould cleaning and remediation.

What should you do to protect yourself and others when cleaning mould?

Cleaning and removing mould may increase the amount of spores and other substances in the air, possibly exposing your skin to direct contact with mould. Follow the checklist below to protect yourself when cleaning mould.

  • Disposable particulate respirator (3M 8210 or equivalent N95-level respirator)
  • Unvented safety goggles
  • Household rubber gloves
  • Remove infants and other family members suffering from asthma, allergies or other health problems from the work area and adjacent room during cleaning
  • Provide isolation measures if sensitive individuals cannot leave the affected or adjacent area. Isolation measures include closing doors and taping the seams or taping plastic sheeting to walls and ceiling
  • Use an exhaust fan to blow air out of a window in the room to help prevent contamination of other areas of the house and provide ventilation

How do you get rid of mould?

The first step to dealing with mould growth is to find the source of the moisture and remove it. If the mould returns after cleaning, then you can be sure the source of the moisture still exists.

Although it is possible for homeowners to clean small mould growth, remediation procedures can get complicated. Seek the assistance of an experienced contractor if you do not feel comfortable eradicating the mould growth yourself.

Follow the guide below for directions on how to clean mould:

  • Washable surfaces
    • Wipe/scrub surfaces using a damp cloth and a mixture of water and unscented detergent
    • Sponge with a clean damp cloth
    • Dry quickly and thoroughly
    • Once dry, vacuum clean the area with a HEPA (high-efficiency particulate air) vacuum cleaner
  • Drywall
    • Wipe surface using a damp cloth and a mixture of water and unscented detergent
    • Dry quickly and vacuum with a HEPA vacuum cleaner
    • Replace drywall if you find mould underneath the paper covering
  • Carpets, fabrics and furniture
    • Try to remove surface contamination from these materials (when dry) using a HEPA vacuum
    • Use wet/dry vacuum for wet materials and once dry, vacuum with a HEPA vacuum
    • Professional drying and cleaning may be required


Remove and dispose of any items that you can not get clean. Make sure to seal these in plastic before disposal. Seal and dispose of the HEPA vacuum contents and clean the washable parts of the vacuum.

Speed up the drying process by:

  • Opening windows
  • Forcing air out the window with fans
  • Removing water from the air with a dehumidifier