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It's Your Health
Mould is a natural part of the environment, but it can become a problem if it finds a damp place to grow inside your home. Indoor mould growth can lead to breathing problems and allergy symptoms for some people. To prevent mould, fix any moisture problems right away and control humidity levels in your home.
Moulds are fungi that grow in damp environments. With enough moisture, mould can grow on many surfaces, including wood, drywall, insulation, ceiling tiles, cardboard, paper and fabric. Excess moisture can be caused by leaks and floods, too much humidity, or condensation on windows and walls. Stale water in humidifiers may also lead to growth of mould and bacteria. Not all mould is visible, so check for signs of water damage or for an earthy smell that may mean you have hidden mould growth.
Health Canada considers mould growth in residential buildings to be a potential health hazard. People living in buildings with dampness or mould are more likely to suffer from symptoms like eyes, nose and throat irritation, coughing, wheezing, shortness of breath or other allergic reactions. Being exposed to mould can also trigger asthma symptoms.
Some people are quite sensitive to mould, while others will not react at all. Health Canada recommends removing any mould found in your home and fixing the underlying moisture problem that allowed it to grow in the first place because there is no safe amount of mould.
Talk to your doctor if you think anyone in your family suffers from health problems caused by mould or poor indoor air quality.
The key to preventing mould is preventing excessive moisture through proper home maintenance. Follow these simple steps:
If you discover a small or moderate amount of mould, you can generally clean it yourself. For washable surfaces, put on some rubber gloves, wear eye protection and a dust mask, and wash the mould away with water and dish detergent. There's no need to use bleach. If a material is heavily covered with mould, or if it is not possible to wash it, consider replacing the material.
Be sure to fix the moisture problem that allowed mould to grow in the first place.
If you have a large amount of mould (covering an entire wall or found in multiple areas), you may want to consider hiring a professional. A large amount of mould is often caused by a major moisture problem that may require professional help to fix, like a leak in your home's exterior wall, foundation or plumbing system.
The Canada Mortgage and Housing Corporation (CMHC) has more detailed information on how to deal with moisture issues and remove mould.
If you have mould growing indoors, you should remove it and fix the moisture problem that allowed it to grow. All moulds can cause health problems and there is no "safe" level of indoor mould, since everybody is different in their sensitivity to mould. So testing often doesn't tell you any more than you already know.
If you think you may have a mould problem, start with a visual inspection of your home. Look for stains or discolouration on floors, walls, window panels, fabrics and carpets. Check for a musty, "earthy" smell. Not all mould is obvious. It can grow inside walls or above ceiling tiles, so it is important to check for mould anywhere that is damp and especially where water damage has happened. If needed, contact an expert to help.
Ideally, you can work with your landlord to clean up any mould and fix the moisture problem. Notify your landlord immediately of any problems, and if needed, provide them with information on mould available from Health Canada or the Canada Mortgage and Housing Corporation (CMHC). Landlord and tenant issues are regulated by the provinces, so if you have any questions about landlord and tenant responsibilities please contact your provinces and territories government.
Health Canada has published a Residential Indoor Air Quality Guideline for mould, which details the health risks and sources of mould. We have similar guidelines for other indoor air pollutants, including formaldehyde, carbon monoxide and ozone.
The Canada Mortgage and Housing Corporation (CMHC) has several publications on ways to prevent moisture problems and maintain good indoor air quality in your home.
Health Canada works with federal and provincial partners to research indoor air quality and its effects on health. These studies are aimed at measuring concentrations of chemical and biological contaminants in indoor air, identifying their sources and developing solutions to maintain and improve indoor air quality.
You can also call toll free at 1-866-225-0709 or TTY at 1-800-267-1245*
Updated : October 2011
Original : September 2002
ę Her Majesty the Queen in Right of Canada, represented by the Minister of Health, 2011