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Facts About...


What is it?

Moulds are fungi that can be found both indoors and outdoors and are a natural part of the environment. Under the right conditions they reproduce by releasing tiny spores. Health problems may result when people are exposed to large amounts of mould and their spores, particularly indoors. Different kinds of moulds grow on different materials. Certain kinds of moulds like an extremely wet environment and others can flourish with just dampness inside the right material. There is no practical way to eliminate all mould and mould spores. However, indoor mould growth can be prevented by controlling moisture. Moist environments and areas with excessive humidity are often found in bathrooms, kitchens and basements, but with adequate ventilation and dehumidification mould growth can be minimized.

Can mould affect my health?

Individuals susceptible to mould may experience various adverse health effects. Characteristics of a susceptible individual may include an infant, someone with a medically confirmed mould allergy, asthma or immune dysfunction. Exposure to mould at sufficient levels can lead to allergenic health effects, trigger asthma or infection. Mould infections, however, are rare among individuals who are otherwise healthy. We all respond differently to mould, if you are experiencing these symptoms see your family physician or contact Telehealth Ontario at 1-866-797-0000.

Can you decrease your exposure to mould?

Indoor mould can be prevented by removing conditions that encourage mould growth. The best method to control for mould is to control for moisture. Specific recommendations include:

  • Repair all water leaks immediately.
  • Caulk around doors, windows bathtubs and shower stalls.
  • Effectively ventilate high moisture areas (run exhaust fans for a half hour after cooking or taking a shower).
  • Use an air conditioner or dehumidifier during humid months.
  • Avoid carpeting in bathrooms and basements.
  • Ensure all rooms have adequate heat during winter months. Cold walls may form water droplets and encourage mould growth.
  • Scrub with an unscented detergent solution, then clean with a wet rag and dry quickly.

If water damaged materials cannot be dried within 48 hours or cleaned effectively they may have to be discarded. If mould growth is extensive, professional restoration services with experience in mould removal may be required.

Rental tenancies

There are steps tenants can take to help control for mould such as:

  • Using exhaust fans.
  • Cleaning up spills.
  • Washing small accumulations of mould (i.e., that may grow around bath tubs and window sills) with water and detergent.

However there are instances where moisture contamination is a result of structural deficiencies. Tenants must report all structural deficiencies to their landlord as they arise. This may include leaking foundations, windows and plumbing among others. Tenants are recommended to take the following steps:

  • Advise the landlord of any water leaks in writing.
  • Contact the Landlord and Tenant Board (LTB) (1-888-332-3234) for further advice.
  • Contact local municipal by-law/property standards if structural issues are suspected to be the source of moisture and they are not being addressed by the landlord.
  • Contact the LTB and apply to have a hearing.
  • Contact the Durham Region Health Department for further information.

Additional resources

More information can be obtained from

Durham Region Health Department, Environmental Help Line 905-723-3818 ext. 2188 or 1-888-777-9613

April 22, 2013