Santé Montréal

Mould

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Description

What are moulds?

  • Moulds are microscopic fungi that grow everywhere in our environment, both inside — except in winter — and outside our living spaces.
  • When they are present in small quantities and are eliminated regularly, moulds do not pose a health problem.  However, when allowed to develop, they spread respirable particulates into the surrounding air and may cause health problems for some people.
  • Conditions that promote their growth in homes and other buildings are the repeated infiltration of water and persistent and excessive humidity.  In order to grow, moulds require high humidity levels, fairly warm temperatures and some kind of food (wood, cardboard, dust, etc.).
  • Moulds do not affect everyone.  Some people will not develop health problems related to moulds even if they are exposed to them. 
  • The most frequent symptoms of exposure to mould are irritated eyes, nose, sinuses and bronchial tubes.

Moulds may also cause or aggravate the following: 

  • Allergic rhinitis, whose symptoms are similar to those of hay fever, although they occur more frequently during cold weather;
  • Asthma;
  • Common respiratory infections such as colds, sinusitis and bronchitis. 

Other symptoms may also arise: 

  • Skin problems such as redness and itching;
  • Sore throat, hoarseness, or loss of voice;
  • Unaccustomed tiredness, memory or concentration problems, etc.

In the great majority of cases, symptoms or health problems caused by mould disappear once exposure has stopped.

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Symptoms

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When to Consult

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Complications

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Protection and prevention

How can I know if symptoms are caused by mould

  • If symptoms subside or disappear outside the contaminated area and then intensify or reappear when you return, they may be related to the environment. 
  • Symptoms often appear more frequently or are stronger during the colder seasons, when windows are closed and no fresh air is circulating in the area.
  • It must also be understood that the presence of such symptoms does not necessarily mean that they were caused by mould.  To know if symptoms are linked to exposure to mould, you will need to visit a physician, who should take all factors and other possible causes into consideration.
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Risk factors

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Help and Resources

For further information on moulds and your health, call Info-Santé at 811.  Parents of school-aged children may also contact the school nurse.

The pamphlet produced by the ministère de la Santé et des Services sociaux du Québec, provides complementary information on this subject.  You can also visit the ministry’s Publications section on its Documentation web page.

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Treatment

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People at Risk

  • Mould does not affect everyone, and, among those affected, symptoms may vary considerably, depending on how strong exposure has been.  For example, spending many hours in a highly contaminated room can be a factor.  Another factor could be a predisposition to react to mould in the air.
  • People who already suffer from allergies, asthma or chronic respiratory such as emphysema or chronic bronchitis are prone to develop symptoms more quickly in the presence of moulds, and they may become more severely affected.
  • People in good health may also develop health problems if exposed to mould, especially if the exposure is prolonged and the quantity of mould is significant. 
  • Exposure to other irritants or allergens, such as animals or tobacco smoke, may also contribute to such symptoms.
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Dernière mise à jour le : 2015.05.22