Mould in Commercial Buildings: Does It Affect the Health of Canadian Occupants? Resource by Camfil, CA


In this blog post air filtration experts present information on mould growth in commercial buildings, explore the health impacts of mould spore inhalation, and offer ways to safely and effectively rid areas of mould.     

Health Canada considers indoor mould growth to be a significant health hazard. Mould refers to fungus that grows in multicellular filaments, and there are well over 200 mould species in Canada1. What is more, approximately 30% of new or remodeled buildings have indoor air quality (IAQ) issues that can be attributable to mould growth2. As mould can grow in a matter of days and often causes a variety of health issues in building occupants, it is necessary that property and facility managers learn about warning signs to look out for, as well as ways to remove mould and improve IAQ after cleanup. 

Five Things You Should Know About Mould Growth Indoors

There are a number of common and lesser known aspects of mould growth. Here are some of the facts, as per the United States Environmental Protection Agency (EPA)3

  1. Mould can be found in virtually every area of commercial buildings; For instance, there are moulds that can grow on wood, paper, furniture, and foods
  2. Common places to check for mould are behind walls or above ceiling tiles 
  3. A small problem can quickly become bigger over time – mould can grow in only 24-48 hours 
  4. The best way to control indoor mould growth is to pinpoint the source of moisture and subsequently eliminate it 
  5. Reduce indoor humidity to decrease mould growth by using exhaust fans, air conditioners, venting moisture-generating areas to the outside, and increasing ventilation

Based on these insights, it is evident that property and facility managers should take care to learn about the ways in which mould can grow and spread in a given environment in order to handle mould contamination effectively. 

How is Mould Growth Linked to Poor IAQ in Commercial Buildings? 

Mould spreads by releasing particles into the air called spores, and the spread is encouraged through humidity. If a space is not well-ventilated and high moisture levels are present, it becomes a veritable breeding ground for mould. Once mould spores are released, they become a catalyst for health problems seen in building occupants. 

Mould also tends to release a musty odour, which can create an unpleasant environment. This can impact an occupant’s productivity and focus, thus leading to disruptions in the workplace. What is more, occupants can become prone to developing detrimental symptoms, allergic reactions, and Sick Building Syndrome (SBS) if mould issues are not addressed.  

What Are the Health Impacts of Inhaling Mould? 

Potential health effects and symptoms associated with mould exposure include asthma, wheezing, coughing, fever, and shortness of breath. Allergic reactions to touching or inhaling mould/mould spores are also common. These allergic responses include sneezing, runny nose, red eyes, and skin rash. In situations where an individual is exposed to mould for a longer period or specifically to Aspergillus fumigatus mould, the health impacts can be more severe. The presence of this mould can lead to bleeding in the lungs, kidney and liver failure, an inability to tolerate exercise, and shock4. Additionally, exposure to Aspergillus fumigatus mould can provoke significant infections, including: 

Pulmonary aspergillosis

This is more likely to develop in people with chronic lung disorders or damaged lungs. As these people are likely to have abnormal spaces in the lungs, fungus can colonize inside lung cavities. As a result, fibres of fungus may clump with white blood cells and blood clots, causing further issues. 

Invasive aspergillosis 

People with weakened immune systems are more susceptible to this infection, which occurs when the infection travels from the lungs into the bloodstream. This is a very serious condition and other organs such as the kidneys, liver, or brain may become infected. 

Allergic bronchopulmonary aspergillosis (ABPA)

As an allergic response to Aspergillus fungus, inflammation is caused in the lungs and air passages and leads to breathing problems. ABPA is more common in people with conditions such as cystic fibrosis and asthma, due to an increased amount of mucus in the airways. 

As mould is a biological contaminant, it can also contribute to SBS. This syndrome occurs when building occupants experience acute health and comfort effects that seem to be linked to the time spent in a particular environment. Chemical contaminants, electromagnetic radiation, psychological factors, substandard building atmosphere, and inadequate ventilation can also contribute to SBS5.   

Mould Cleanup In Your Commercial Building 

To avoid workplace disruptions, allergic reactions, infections, and SBS, it is critical that mould is removed and mould spore particles are captured. As a first step, sources of moisture should be identified and water leaks should be fixed. Without doing this first, mould will reappear. Next, building managers should determine the total surface area of a given space that is affected by mould. If this area is large, meaning a single patch is larger than 3 m2, then an expert assessment and cleanup is required6. If the area is small, it is safe for the average person to clean the mould with adequate protective gear. 

Air handling units can also contribute to mould issues within a building. These units are perfect breeding grounds for mould as they have the 4 key ingredients: moisture, darkness, warmth and food. To avoid mould issues within these units, filters should be positioned in an area of least moisture (a distance away from the intake, before humidifiers, etc.) when possible. Using a high MERV rated filter and proper sealing around the filters will help remove any mould spores which may be growing inside the unit before the filters. Mould growing on the filter itself is definitely a concern which requires investigation into the cause and a remedy. Antimicrobial filters are not a solution and should be avoided at all costs. Fortunately, we offer various solutions for every air quality concern. The Hi-Flo ES from our general ventilation filtration product mix is the longest lasting pocket style filter available in the industry, requiring less frequent filter changeouts and less landfill waste. The City-Flo is also highly effective in capturing mould spores, and  contains a molecular air filter to control odours. 

If upgrading mechanical ventilation is not feasible, or if a specific area requires extra care, the CamCleaner CC500 from our air purifier line is an ideal solution. It has smooth rolling caster wheels for portability and contains a combination HEPA/gas removal filter, thus providing the highest level of filtration available. 

There are a variety of factors that determine which air filtration solutions will best protect your facility from mould. Be sure to contact an experienced commercial building air filtration consultant to find the air filtration solutions that are right for your building. 

About Camfil Canada Clean Air Solutions 

For more than half a century, Camfil has been helping people breathe cleaner air. As a leading manufacturer of premium clean air solutions, we provide commercial and industrial systems for air filtration and air pollution control that improve worker and equipment productivity, minimize energy use, and benefit human health and the environment. We firmly believe that the best solutions for our customers are the best solutions for our planet, too. That’s why every step of the way – from design to delivery and across the product life cycle – we consider the impact of what we do on people and on the world around us. Through a fresh approach to problem-solving, innovative design, precise process control, and a strong customer focus we aim to conserve more, use less and find better ways – so we can all breathe easier. 

The Camfil Group is headquartered in Stockholm, Sweden, and has 33​ manufacturing sites, six R&D centers, local sales offices in 30 countries, and about 4,80​0 employees and growing. We proudly serve and support customers in a wide variety of industries and in communities across the world. To discover how Camfil Canada can help you to protect people, processes and the environment, visit us at


Media Contact: 

Holly Gardner 

Camfil Canada Inc. 

T: 437-929-1161


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