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Mould is a ubiquitous fungus in outdoor environments that inevitably makes its way indoors. The general population is commonly exposed to mould through inhalation, and less commonly through direct contact, with no adverse effects. However, individuals with asthma or other underlying respiratory ailments may show sensitivity to mould or its cellular components that may trigger respiratory tract irritations (coughing, shortness of breath) or exacerbate existing respiratory symptoms. If an indoor condition such as excess moisture results in mould growth, elevated concentrations in the indoor environment can increase the risk of exposure to mould. Mould growth in an indoor environment is a supporting indicator of deteriorating building integrity and indoor air quality.

The assessment of mould exposure is complicated, requiring investigations that include qualitative observations and, when the presence of mould is uncertain but suspected, quantitative measurements. With varying responsibility and policies across Canada, public health inspectors and other environmental health professionals may respond to public inquiries about mould in indoor environments by providing information, conducting walk-through investigations, and/or reviewing microbial laboratory reports from surface or air sampling. Evidence of mould growth in an indoor environment generally prompts action to remove the mould and remediate the conditions that promote its growth. Complex cases may require the involvement of professionals with specific knowledge, training, and experience in mould assessment and remediation.

NCCEH Resources

Evidence reviews:



Select external resources

Institut national de santé publique du Québec (INSPQ) English documents :

  • Mould Compendium (2017)
    This webpage lists a series of descriptive fact sheets on some common moulds present in the indoor environment.
  • Integrated management of residential indoor air quality: A call for stakeholders in a changing climate (2017)
    This peer-reviewed publication examines the impacts of climate change on indoor air quality (IAQ) and discusses the effectiveness of various adaptation measures that integrate various determinants of IAQ (building design, use of interior materials and furnishings, ventilation, and occupant behaviours). The authors made recommendations for different stakeholders to proactively develop integrated adaptation plans for building owners and managers to mitigate and prevent impacts of climate change on thermal comfort and IAQ.
  • Health risks associated with the indoor presence of moulds (2016)
    This is a summary of a scientific report produced by the INSPQ Task Force who conducted a literature review on the topic.
  • Household Mould: Get Rid of it (2002)
    This fact sheet is written in plain language and is suitable for both professional use and as public education material.

Health Canada:

  • Mould (2019)
    This webpage provides an overview of health risks, signs of mould, mould remediation and prevention, a point relevant to landlords/tenants, and reports and publications on the topic.
  • Infographic: Mould (2017)
    This bilingual infographic depicts a visual overview of mould and its causes, health effects, who is at risk, what to do when there is mould in the home, and ways to prevent mould growth.


Canada Mortgage and Housing Corporation 

  • Mould in Housing 
    This series of guides was developed by CMHC and Health Canada with a First Nation's perspective.  It provides advice for home owners/occupants, housing managers and builders. 


This list is not intended to be exhaustive. Omission of a resource does not preclude it from having value.




Last updated Mar 17, 2020