Mould and Indoor Air Quality

Mould is a commonly found problem in homes and buildings and it affects people differently. For some individuals, it can lead to allergic reactions including rashes, coughing, eye irritation, or respiratory conditions including asthma in children. In extreme cases, exposure to certain types of toxigenic moulds such as Stachybotrys chartarum has been linked to more serious chronic health issues (though this is an area where research is ongoing). While exposure to mould spores is unavoidable, factors in the home can lead to greater concentrations of allergenic and toxigenic mould. In some cases, mould issues indoors have become so severe that residents are forced to leave their homes until the problem is addressed. Early detection and remediation is critical to avoid more serious and costly problems down the line.

Factors that Lead to Mould Growth

Mould requires moisture to grow. Mould colonies tend to form when mould spores in the air land in areas of high moisture such as:

• Attics, which can be particularly problematic due to high humidity from moisture condensation and limited air flow
• Bathrooms and laundry rooms where steam is produced and condenses
• Flooded basements
• Places where there is a leak or plumbing back up.

Commonly used building products such as wood and drywall tend to support the propagation of mould by acting as a source of nutrients.

What to do When You Suspect Mould

Mould is sometimes detectible by sight or smell (a damp odour), but it is often hidden and its presence unknown without indoor air quality testing. Unfortunately, there is no way to tell how bad a mould problem is for two reasons. First, testing is required to determine the type(s) of mould present. Second, often the mould problem goes beyond the surface and exists behind walls or under flooring. If you see or suspect abnormal mould contamination, you should contact professionals to assess and remediate.

It is important for you or your professional to determine the underlying reason for the mould growth. Without first indentifying and fixing the moisture source supporting the mould growth (e.g., condensation or basement leak), your problem will likely continue to persist. Remediation and clean up strategies for mould vary depending on the type of mould and the degree of contamination. In cases of small surface mould, mould can be removed with scrubbing and disinfection with a simple 50% vinegar solution. Commercial cleaners are also available, though not always necessary.
For larger problems, professional advice is typically warranted as the size of the cleanup effort will vary depending on the extent of contamination. When undertaking mould remediation, it is important to have the right personal protection including N95 masks (or better), non-porous gloves, protective goggles and a protective suit.

Preventing Mould Growth and Proliferation

Some effective strategies to prevent mould issues in the home include:

• Keep humidity levels low (between 30% and 60%). Consider a dehumidifier if your home tends to get humid.
• Ensure proper ventilation including exhaust fans in the kitchen and bathrooms.
• Clean surfaces regularly
• Proactively correct problems in the home that can lead to moisture intrusion or leaks. For example, keep gutters clean and use extended drainpipes to keep rainwater away from the house.
• Avoid carpeting, particularly in basements.
• Use moisture resistant building products where appropriate and ensure adequate use of vapour barrier.
• Clean up and dry moisture affected areas quickly and thoroughly