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10 steps for eliminating mould in the workplace

Mould can lead to infections, allergic reactions

By Carolyn Wisdom

Mould investigations in the workplace are often triggered by complaints of illness. In many cases, the mould is visible inside the building or there is an odour. These signs are frequently ignored. It is not until workers experience adverse effects that employers take action. This is not intentional, but stems from a lack of understanding of what mould is and how it can affect workers’ health.

Fungi (moulds) are living organisms. They are found everywhere in our environment. Under the right conditions, they will start to grow indoors, particularly if the building is not well ventilated. Fungi will grow on building materials, on drywall, on wooden window frames, under carpets, and in crawlspaces. One of the difficulties is that there may be a small amount of visible mould, but a large amount of hidden mould. This is the “iceberg effect” of mould.

The other concern is that mould is not like asbestos. It will not stay in one place. Because it is living, it will continue to grow if it has the right conditions. The number one condition for mould growth is the presence of moisture or free water.

There are instances of mould infestation in Canadian workplaces. One well-known case was inside a historic courthouse in Calgary. The mould problem started in the 1990s, originating due to inadequate vapour barriers installed during renovations. During the investigation, a health questionnaire was administered to the occupants. The majority of occupants reported three or more health-related symptoms. A report in the Edmonton Journal indicated that 43 justices and staff members were evacuated from the courthouse. The court was temporarily moved to Edmonton in 2001. The article said that staff members complained of headaches, chronic fatigue and asthma-like symptoms. One justice required oxygen.

“Fearful of carrying the mould to their new quarters, staff members entered the Calgary offices dressed in Hazmat suits to reproduce the court’s pertinent files by scanning,” the article said.

Recently, I attended an asbestos refresher course in Calgary. Many of my classmates were mould remediators who recalled the Calgary courthouse incident. They said that the old courthouse still stands empty even though the mould was apparently removed. I, myself, have conducted mould investigations in cases where the buildings were demolished in large part because of the mould. In these cases, a number of staff members were ill and had to take extended time off work.

Moulds affect indoor air quality when they grow inside a building. There are two ways that this can happen:

•Fungal spores are disseminated into the air.  Fungi growing as strands of hyphae produce thousands of reproductive propagules called spores. These spores cannot be seen individually with the naked eye. Workers and members of the public can breathe these spores into their lungs.

•Fungal chemicals become airborne. Moulds produce chemicals as byproducts of their metabolism. These chemicals can also be inhaled. Categories of chemicals produced by moulds are: antibiotics, volatile organic compounds (VOCs), and mycotoxins.

Occupants in mould-contaminated buildings often experience symptoms. However, the specific effects and the extent of these effects are not always consistent. One reason for this is because people differ as to the status of their immune systems and their tendency to become ill.  The very young, the elderly, those with pre-existing conditions, and those whose immune systems are compromised are more susceptible to the harmful effects of mould. Examples of immuno-compromised people are those undergoing cancer therapy or those who have diseases such as AIDS.

Certain types of moulds are linked to specific health effects. These health effects are:

•Infection: Certain moulds are known to cause infections, particularly in immuno-compromised individuals. One example is invasive Aspergillosis, a lung infection usually acquired in hospitals. It is considered the most common fungal infection worldwide.

•Allergic reaction and irritation.  Small fungal spores are able to penetrate into the deep lung. Many indoor fungi are linked to asthma attacks and symptoms of a runny, stuffy nose.

•Toxicosis. Toxicosis is the reaction of the body to mycotoxin exposure. Most reports of mycotoxin exposure have been from cases relating to ingestion of mould.

Steps for employers

What should employers do when there are complaints of illness, mould contamination or water intrusion into the workplace? The primary legal obligation is always to protect the worker. Mould hazards are just like other hazards in that they can be eliminated, controlled or mitigated by the use of personal protective equipment. The most common control is elimination, but this is not always possible. It is important that employers show due diligence, that they take all reasonable steps to protect people. They should also document these efforts.

Here are the common steps in a mould investigation that employers can follow:

•Act immediately if there is significant water intrusion. Call a restoration company. Otherwise, continue with the following steps.

•Find a qualified consultant to assess the situation. There is no single standard for consultants’ qualifications. Occupational/industrial hygienists have university training and professional exams in this field. Certified home inspectors have building knowledge, but may not have training in the health effects of moulds.

•Arrange a meeting between the consultant, owners, managers or maintenance people. The consultant can then continue with the remaining steps.

•Conduct a site investigation to look for water damage and mould (visible or hidden).

•Conduct confidential interviews or a health survey if workers are reporting ill effects.

•Conduct sampling. Sampling is usually necessary for workplaces and public buildings. It may take the form of a swab or piece of material (drywall, vacuum samples or water samples) or air sampling.

•Produce a written report with results and recommendations for remediation. Focus on where the mould was found, the extent of contamination and the types of moulds identified for both surface sampling and air sampling. The concentrations of specific mould types in the air in various locations should also be included.

•Remove staff or occupants if the situation is warranted, particularly if there will be disturbances to the mould. If in doubt, treat mould like asbestos.

Remediate the building or site. This involves removal of the mould’s water source; cleaning or removal of the contaminated mould; assessing the effectiveness of the clean up by visual means and sampling (both surface and air).

•Communicate to the occupants the final outcome. Don’t forget this final but important step.

Carolyn Wisdom

Carolyn Wisdom is a health and safety consultant based in Edmonton. She is a Certified Industrial Hygienist, a Canadian Registered Safety Professional and a Certified Safety Auditor. She has more than 25 years field experience and has been conducting health-related mould investigations for the past 15 years. She can be reached at Visit for more information.
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