Dampness, Mould and Indoor Air

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The Issue

Reduced natural ventilation, too much humidity, the use of chemicals and other factors can lead to unhealthy air in your home or workplace, causing a number of health problems such as respiratory symptoms and allergies.

Background

On average, Canadians spend about 90 percent of their time indoors, so the quality of indoor air is very important. Humid or damp conditions in your home can encourage the growth of mould and dust mites. Unless you use a vacuum cleaner with high efficiency filters, floors, carpets and upholstery can build up mould spores, bacteria and sources of allergies.

Mould can develop from too much humidity, building leaks, refrigerator drip pans, bathroom surfaces and flooding. Mouldy smells from carpets, wood and gypsum board are a sign that they harbour fungi. Stale water in humidifiers and air conditioners can lead to the growth of bacteria and fungi. Air filters also collect dust and contaminants.

A major cause of poor indoor air quality is a lack of fresh air, that is, not enough exchange of air between the outside and inside. Where there is a lot of water vapor, such as in the bathroom, mechanical ventilation such as a fan may be needed eliminate excess humidity.

The Risks of Poor Air Quality

Contaminants often found in damp buildings are associated with a number of health problems, including diseases such as asthma or allergic rhinitis and non-specific symptomssuch as cough, wheezing and headaches.

Moulds are filamentous fungi that grow in damp environments. Mould spores contain allergens and irritants. People living in houses where moulds grow are more likely to suffer from asthma or respiratory symptoms.

Viruses can also be found indoors, but they don't survive long in the air. Viral infections usually result from contact with infected people.

Minimizing Your Risk

Improving indoor air quality is fairly simple. Here are several steps you can take.

• Control the humidity and let more air into your home to prevent moisture from building up on walls and windows. Where there is a lot of water vapor, such as in the bathroom, mechanical ventilation such as a fan may be needed eliminate excess humidity.
• Measure humidity using a hygrometer, to see if you need a dehumidifier. It is advisable to keep the relative humidity in your home below 50% in summer and 30% in winter
• Repair leaky roofs, walls and basements.
• Clean mouldy surfaces with a strong detergent
• Keep your home clean and dust-free.
• Regularly clean and disinfect humidifiers and air conditioners.

If you have severe humidity or contamination problems, ask your provincial or regional health department for advice. Check the sources listed below for more information on the problem. Talk to your doctor if you think anyone in your family suffers from health problems caused by poor air quality.

Government of Canada's Role

Health Canada has published a number of pamphlets and reports about indoor air quality. The Canada Mortgage and Housing Corporation (CMHC) also has several publications on how to reduce and avoid too much humidity in your home and how to improve indoor air quality.

Health Canada and CMHC are currently working on a joint research project on air quality in homes. They are looking at how the chemicals and toxins produced by Mould, bacteria and other contaminants can affect your health.

Need More Info?

For further information see these publications available from Health Canada and CMHC:

Health Canada - Publications on health and air quality
Or contact:
Air Health Effects Division
Health Canada
400 Cooper Street, 2nd Floor P.L. 4602C
Ottawa, ON K1A 0K9
Tel: (613) 957-1876
E-mail: air@hc-sc.gc.ca

Health Canada's Toxic Substances Research Initiative, Urban Air Quality and Human Exposure to Airborne Pollutants

Health Canada's Climate Change and Health

Children's Environmental Health

For more information on Humidifiers see the It's Your Health article on Cool Mist Humidifiers

For more information on moisture and mould in your home visit the Canada Mortgage and Housing Corporation series "About your House"

Or call : 1-800-668-2642

For additional articles on this subject and other issues go to the It's Your Health Web site. You can also call (613) 957-2991

İHer Majesty the Queen in Right of Canada,
represented by the Minister of Health, 2004
Updated: May 2004
Original: September 2002