Mould, Dampness and Humidity

Since moisture promotes mould growth, dampness is one of the most common causes of poor indoor air in homes, classrooms and public spaces. Controlling the level of moisture is one of the best and easiest ways to improve indoor air and protect your health.

Mould is the common word for any Fungus that grows on food or damp building materials. It often looks like a stain and comes in a variety of colours. In some cases, however, mould may not be visible but may have a musty odour. If it is allowed to grow, mould can contribute to poor indoor air quality.

In order to reproduce, moulds release "spores" into the air and these spores are small enough that people can actually breathe them in. Mould spores are always present outdoors. So, when mould grows indoors, the number of mould spores and fragments is usually higher indoors than it is outdoors. High concentrations of airborne mould spores can have a number of adverse health effects.

This section provides detailed information about mould and the effects it can have on your health. It also offers tips for how you can remove mould, prevent future growth and improve the quality of your indoor air.

Health Canada helps protect Canadians from the effects of mould by conducting research and by providing information about healthy indoor air.

Find Out More

• It's Your Health: Dampness, Mould and Indoor Air
• Health Canada's Residential Indoor Air Quality Guideline for Mould
• Fungal Contamination in Public Buildings: Health Effects and Investigation Methods
•  Health Risks Associated with the Indoor Presence of Moulds: Institut de Santé Publique du Québec (INSPQ) (PDF Version - 356 K)
•  U.S. Environmental Protection Agency: Mold Course
•  The National Collaborating Centre for Environmental Health (NCCEH) for evidence reviews on Health Effects of Mould Exposure in Indoor Environments; Mould Assessment and Mould Remediation.
•  Canada Mortgage and Housing Corporation (CMHC): Moisture and Mold