Can mold in a Calgary basement affect asthma?

Health Canada does not give a mould level that is safe or unsafe for any person: it says the number of mould species and the variability in how people respond preclude setting exposure limits. If you have asthma, that is a question for your doctor. What Health Canada does say clearly is this: control humidity, repair water damage promptly, and clean any visible or concealed mould.

The size of the affected area shapes what you should do next. Health Canada and the Canada Mortgage and Housing Corporation describe three bands. A small area is one to three patches, each under one square metre (about ten square feet); a person in good health can clean that with water and dish detergent, wearing safety glasses, a disposable N95 respirator and household disposable gloves. A medium area is more than three patches, or a single patch larger than one square metre but under three square metres; CMHC says that calls for qualified and trained maintenance staff. An extensive area, any patch larger than three square metres, calls for qualified and trained mould remediation contractors.

A few things matter before you start cleaning anything in a pre-1990 Calgary home:

• If the basement has drywall compound, vinyl floor tiles or stipple, disturbing them to reach mould behind a wall or under flooring raises an asbestos question. Alberta OHS bulletin ASB004 names drywall mud and vinyl flooring for buildings built before 1990, and the Alberta Asbestos Abatement Manual adds stippled finishes.
• Alberta Health Services notes that porous materials such as drywall, carpet and ceiling tiles typically need removal, not just surface cleaning.
• Alberta Health Services also says air testing for mould is usually not recommended, especially when you can already see it. Paying for air sampling before you have dealt with visible mould is rarely useful.
• Keep indoor relative humidity between 30 and 50 per cent. Mould can begin growing within 24 to 48 hours on a damp surface, so fixing the moisture source comes before any cleaning.

If the area is medium or extensive, or if removing affected drywall or flooring is part of the job, submitting a request through the form on this page will put your details in front of local remediation contractors listed in the Calgary Construction Network directory.