What are moulds?
Moulds are members of the fungus family, along with mushrooms and yeast. There are thousands of different types of moulds, and they are usually present in air, indoors and outdoors. Moulds play an important role in helping to compost decaying materials like plants. But they can pose health risks as well.
How do moulds grow?
Moulds can get inside buildings through doors, windows, heating, ventilation, and air conditioning systems, and through small openings and cracks in walls and foundations. They can also be brought in on clothing, shoes and the skin and hair of people and pets.
Indoor, moulds need two things in order to grow: nutrients (food) and moisture. Nutrients available indoors include
- building materials,
Moulds usually grow in areas, which are damp or humid in places like
- air ducts,
- porous insulation,
- fan coil units,
- condensation or drip pans.
They can also grow on building materials such as
- ceiling tiles,
- window casings,
- foundation walls, especially if these are damp or wet.
How can moulds affect your health?
When most kinds of moulds are present in indoor air at the same level as outdoors, they usually do not pose a health risk. Moulds that grow indoors are usually different from typical outdoor moulds, and can pose more risks to health.
Moulds can release spores (their offspring) and various chemicals into the air. When mould levels build up, they can trigger allergies and asthma attacks in some people. Certain types of moulds can be even more hazardous, especially when they actually grow on indoor surfaces. Some moulds can produce toxins, which can poison indoor air and cause illness. Exposure to elevated levels of indoor moulds can affect health in four major ways:
- Irritation, causing symptoms like eye, throat, and skin irritation.
- Allergies, including symptoms similar to hay fever, asthma attacks (between 10% and 30% of asthmatics are allergic to moulds), and dermatitis. Allergies to indoor moulds may not be detected by standard allergy tests, which measure reactions to outdoor moulds.
- Toxicity, which can cause headaches and flu-like symptoms like fever and cough, diarrhoea and fatigue. Breathing in mould toxins has been linked to serious illnesses and with sick building syndrome (SBS).
- Infection, normally a risk only for people with severely weakened immune systems, such as those on chemotherapy and people living with HIV/AIDS, and for victims of severe burns whose skin has been damaged. Only certain moulds can cause infection.
Who is at risk?
Anyone can be affected by moulds, but some people are more susceptible than others, including:
- People with asthma or allergies to moulds;
- Infants and young children, whose lungs are still developing; and
- People with weakened immune systems.
- Factors that increase the risk to health include:
- Exposure to high levels of moulds;
- Exposure to moulds for a long period of time, or repeated exposures to elevated levels for short periods; and
- Exposure to those species of mould, which can produce toxins (poisons).
What is Stachybotrys atra?
Stachybotrys atra (or chartarum) is one species of mould, which can produce toxins (poisons). It is dark green to black in colour, and grows on cellulose-based materials like wood, paper, and drywall when these have been damp or wet for prolonged periods of time. It does not grow on food or on materials like bathroom tiles, and does not grow in the body.
Stachybotrys has been linked to severe illness and deaths of several infants in Cleveland. The infants developed bleeding of the lungs. It is suspected, though not proven, that the infants were exposed to high levels of mould toxins by breathing Stachybotrys spores. The toxins produced by Stachybotrys can cause haemorrhage. Infants are more susceptible to airborne toxins than older children and adults because their lungs are growing very quickly.
There is little documentation available about how commonly Stachybotrys occurs in indoor environments. Until more studies have been done, experts recommend that infants under one year of age should not be exposed to buildings with mould problems or un-repaired water-damage. This is good advice for people of all ages.
What can you do about Moulds?
The best way to reduce indoor mould contamination is to prevent or control conditions that encourage its growth. All surfaces and furnishings should be kept as clean and as dry as possible. Water leaks or condensation problems should be remedied without delay. Caution must be used during mould cleanup, which can release mould particles and spores into the air. A professional can provide guidance on proper clean-up measures. When experiencing extensive mould growth, which may occur when it takes a long time for things to dry after a flood, professional help may be necessary. If you notice mould or moisture accumulation in public buildings like schools, you should notify the principal or superintendent.
Moulds are found everywhere in the environment, both indoors and outdoors. Most moulds are not harmful, but some people with allergies, asthma or other lung conditions, or immune problems may be more at risk from exposure to some moulds. However, no one should be expected to live or work in buildings with ongoing mould problems. If you or a family member experience symptoms that are severe or long-lasting, consult your health care provider and discuss if moulds are a possible cause.
Where can you get more information?
The following agencies can provide information on indoor moulds, their health effects, proper mould clean-up procedures, and advice on health problems related to indoor air quality.
Ottawa Public Health, Environment & Health Protection Division Tel: 613-580-6744, ext. 23806.
Canada Mortgage and Housing Corporation:Tel.: 613-748-2367 TDD: 613-748-2447
The Lung Association CAN-DO Program: Tel.: 1-800-97-CANDO