Dealing With Mould (Mold)

“Classroom Closes After Black Mould Found in School” was the headline in a recent Saskatoon StarPhoenix. A teacher who worked full time in this room reported feeling ill and believed symptoms resulted from working in this room. The Board of Education replaced sections of the wall, floor and carpet.

Most moulds are harmless and are more an annoyance than a danger, but some can be dangerous. “If we all run out screaming every time we hear about a mouldy building, it won’t help any. We have to keep our heads and know what we’re dealing with,” says Don Figley, Figley Consulting Associates Ltd.

What is mould?

Moulds are growths of minute fungi forming on plants, food or animal matter. They are found everywhere – indoors and outdoors. They are commonly a furry growth associated with the decay of matter. Mould growth can be seen in the form of discolouration ranging from white to orange, red, green, brown, and black. A musty smell is often present. Most of the time most of the moulds are not dangerous, just offensive.

Are moulds good or bad?

Moulds can fall into either category. Some moulds are used to make many desired consumer products such as antibiotics, cheeses and beverages. Some moulds, if contamination is extensive, can cause allergic reactions, asthma episodes, infections and other respiratory problems. Exposure to high mould spore (seed) levels can cause development of allergies.

What does mould need to grow?

  • food source such as leaves, bread, food, dust, paper, wood, fabric, carpeting
  • source of moisture
  • temperature, usually around 80°F (22°C)
  • space to grow

These conditions are commonly found in basements, kitchens or bathrooms.

What should I do with mouldy food?

If there is mould that is not a normal part of the food (the blue in blue cheese), it is recommended that the food be thrown out. Cheese (such as cheddar or cottage), tomato paste, processed meats, breads, jams and jelly are among the foods that can develop moulds. It is recommended that they be disposed of and not eaten.

Where do moulds like to grow in a building?

Moulds thrive in damp, warm, dark, poorly ventilated places. Basement walls, closed up closets, bathroom crevices, behind wall paper, in clothes hampers, damp carpet, and on window sills are places where moulds can thrive.

Moulds can also cause buildings to decay or dry rot which can result in extensive maintenance problems and costs.

How am I exposed to moulds?

Moulds are found everywhere – indoors and outdoors. People are exposed to outdoor moulds on a daily basis. Indoors, it is common to find mould spores(seeds) in the air of buildings and growing on damp surfaces. These indoor moulds can cause health problems when they are in the air and in large quantities.

Who is at greater risk when exposed to moulds?

  • infants and children
  • the elderly
  • immune compromised patients ( people with HIV, infection, cancer chemotherapy, lung disease)
  • pregnant women
  • individuals with existing respiratory conditions, such as allergies, multiple chemical sensitivity, asthma

Even if you are not sensitive to moulds, no one likes them as they smelly, dirty, slimy, ugly and just plain unhealthy!

What health symptoms are common?

Allergic reactions may be the most common health problem of mold exposure. Symptoms alone or in combination may include:

  • respiratory problems, such as wheezing, an difficulty in breathing
  • nasal and sinus congestion
  • eyes – burning, watery, reddened, blurry vision, light sensitivity
  • sore throat
  • nose and throat irritation
  • shortness of breath
  • skin irritation
  • central nervous system problems ( constant headaches, memory problems, and mood changes)
  • aches and pains
  • possible fever

Are some moulds more dangerous than others?

People vary in their response to both the quantity and type of moulds. In addition, some moulds can produce toxins and can be present in both living and dead mould spores. Materials permeated with mould need to be removed, even after they are disinfected with cleaning solutions.

How can I tell if I have mould in my house?

If you see mould or if there is a musty odour, you can assume you have a mould problem. Look for water damage. Mould likes to grow where there is or has been water or dampness. Speckled or discoloured carpet, wall board or fabric may indicate the presence of mould.

Vacuuming may increase your exposure to mould spores as they can pass through the vacuum filters. Central vacuums that vent outside or ones with HEPA filters can lessen some exposure.

Should I test my home for mould?

Most health districts do not recommend testing as the first step to determine if you have a mould problem. Reliable sampling for mould can be expensive, and require equipment not available to the general public. Home owners may hire a contractor to do the testing. Health districts usually do not include this in their services. Also, there are not reliable standards on which to base what is an acceptable level of mould. The level that might have an effect on some people may not affect others.

The simplest approach is: if you can see or smell mould, you have a problem. Once you know you have a problem, consider the following:

  • seek information from you health board
  • realise that unless the source of moisture is removed and the contaminated area is cleaned and disinfected, mould is likely to reoccur.

General clean-up procedures:

  • identify and correct the moisture source
  • clean, disinfect and dry the mouldy area
  • bag and dispose of any material that has mould residues.

What can I save? What should be tossed out?

Anything that is porous such as cloth, wood, paper, wallboard, carpet should be discarded. Things that are glass or metal can be saved after they are disinfected.

Removal of Mouldy Materials

Spores are easily released when mouldy material is dried out. After fixing the moisture source, cleanup can begin:

  • wear rubber gloves, a mask and clothing that can be easily washed or discarded when handling mouldy material
  • ventilate working area
  • try test cleaning a small area – if you are adversely affected, consider paying a licensed contractor or professional to do the work
  • remove the porous materials
  • carpeting can be a difficult problem because drying does not remove the spores – if there is heavy mould, disposal of the carpet should be considered
  • bag and discard mouldy materials
  • allow area to dry for 2-3 days (ventilate if possible)
  • if flooded, remove all sheet rock to at least 12 inches above the high water mark – this step may need to be carried out by a licensed contractor
  • air house during and after the work

To disinfect surfaces:

  • After thoroughly cleaning and rinsing, disinfect the area with a solution of 10% household bleach (e.g., 1 1/2 cup bleach per gallon of water). Using bleach straight from the bottle is not more effective. Let the bleach solution sit on the infected area for 15 minutes.
  • Never mix bleach with ammonia – the fumes are toxic.
  • When disinfecting a large structure, make sure the entire surface is wetted down, but not excessively.
  • Let disinfecting areas dry naturally overnight – this extended time is important to kill all the mould.
  • Make sure the area is well ventilated during and after work.

What do I do with mouldy household items?

  • anything that has been wet or damp for weeks should be thrown out
  • items such as pillows, mattresses, bedding that you come in close contact with on a daily basis should be thrown out
  • bleachable items should be washed in detergent and 1 cup of bleach per load
  • slightly mouldy items that can not be bleached may sometimes be cleaned in baking soda or washing soda or may be dry cleaned

After I’ve cleaned everything as thoroughly as possible, can I still have mould odours?

Yes, mould odours can persist. Continue to dry out the area and search for more hidden mould. If the smell continues, you may have to re-clean the area. Be sure to ventilate the area. Ensure the area is dry before replacing flooring or rebuilding.

What can I do to lessen the chances of mould forming in the house?

  • Keep the home as clean and dry as possible.
  • Keep relative humidity between 30 and 50% with close to 30% in the winter.
  • Keep the home well ventilated.
  • Watch for sources of moisture such as leaky taps, dripping windows or pipes, cement cracks and correct them immediately.

For more information contact:

  • your local health district
  • Canadian Mortgage and Housing Corporation, 700 Montreal Road, Ottawa, ON, K1A 0P7, Phone: 1-800-668-2642
  • environment consultants – yellow pages of telephone directory
by Millie Reynolds, Home Economist