Mould and Health: Questions and Answers

November, 2003

Canada’s National Science and Technology Workshop on Mould In the Indoor Environment was held on November 24-25, 2003. It was hosted by the Healthy Indoors Partnership and Health Canada. Over 80 experts from across Canada and from all fields relevant to human health and moulds in indoor environments worked on a national plan for indoor mould and health research. Prior to leaving for the workshop, CASLE’s representative asked Nova Scotia government staff in the Education and Labour departments if they had any specific questions for the workshop. Here are the departments’ questions and the answers provided by experts at the workshop:

Q. How effective are Health Canada approved antimicrobial agents? (These are antimicrobial sprays/treatments commonly recommended by companies doing mould removal work in buildings, or by those wanting to prevent mould growth in buildings or on surfaces.)

A. Although antimicrobial agents do work somewhat, some cautions were underlined:

a. They should never be used in place of remediation of existing mould or for avoiding repairs to damp conditions.

b. They may introduce health concerns themselves.

c. They are not necessary for successful remediation.
d. Any dirt or film can prevent the products from being effective at all. Participants were directed to the “Guidelines on Assessment and Remediation of Fungi in Indoor Environments” (otherwise known as “the New York Protocol”) which advises against their use. See page 9 of the executive summary on

If there is moisture for at least 24 to 36 hours, there is likely to be mould growth. Repairing the source of dampness is essential.

We also now have Health Canada’s guidelines:

Other excellent Websites:

Canadian Construction Association, Mould Guidelines:
Mould Remediation in Schools and Commercial Buildings:

Q. Is there research into the most effective monitoring methods for microbials?

A. Yes, but not nearly enough, particularly for finding hidden mould. Overall, if you find or smell mould, get rid of it and remediate the SOURCE of dampness and remove contaminated materials according to the documents above.

Q. Is there value in routinely identifying moulds found in buildings?

A. There is not much value in identifying moulds. If any mould is present, remediation is necessary and the precautions taken depend mostly on the size of the colony. Postage stamp size requires little precaution, while several square feet requires much protection of occupants and workers, and requires more stringent isolation techniques. The hard part is finding mould if it is behind walls, under flooring, and the like. There was some discussion of new techniques for finding hidden mould, such as infra-red tests.

Q. Are there guidelines for exposure?

A. There was consensus among medical participants that mould exposures can’t be quantitative or even species specific because of the huge number of variables, and also because susceptibility of individuals varies so much.

For example, children and those with medical conditions such as asthma, allergies and other conditions would be expected to require more protection.

In the meantime, for isolation/remediation, it was proposed that asbestos isolation/remediation guidelines could serve until specific mould guidelines are developed. It is not that mould and asbestos risks are interchangeable, but rather that they are close enough to work, and the precautionary principal may be the best approach from a public health standpoint.

K. Robinson
for CASLE (Canadians for A Safe Learning Environment)