Mould (also spelled as mold) and fungal spores are ubiquitous (that means they are practically everywhere). Fungal spores are typically present indoors by travelling in the air from outdoors. However, mould growth should not be able to establish itself indoors in normal conditions.
Mould needs 3 conditions to grow: a growth medium (such as drywall, wood, even dirt), temperature ideally between 20-30oC but can grow from 5-40oC, and moisture. Indoor environments always have ample growth mediums, and temperature is typically in the ideal growth range. The presence of moisture, such as through flooding or even very high humidity, can turn an indoor environment into an ideal environment for mould growth.
Mould can be both an irritant and an allergen. Not all mould exposures result in irritation. Not all moulds are allergenic (allergy-causing).
Mould exposure can occur when there is mould growth indoors, as well as when a mould remediation is occurring. Mould growth indoors should be promptly removed, with the greatest care and appropriate procedures and personal protective equipment (PPE) to ensure the safety and health of all who are working in the area.
Mould Remediation (infographic)
Mould Abatement Guideline (Environmental Abatement Council of Canada (EACC))
Mould Guidelines for the Canadian Construction Industry (Canadian Construction Association (CCA))
Indoor Air Quality - Mould and Fungi (Canadian Centre for Occupational Health & Safety (CCOHS)):