Mould growing on the back side of wallpaper

Mould/Microbial Remediation

What are moulds?
Moulds are microscopic fungi, a group of primitive plants which includes mushrooms, mildew, and yeasts. Moulds are present everywhere, both indoors and outdoors. There are over 100,000 species of mould of which at least 1,000 are common to Canada.

How does mould grow?
All moulds need water to grow. Mould can grow almost anywhere there is water damage, high humidity or dampness - providing a food source is available. Most often moulds are confined to areas near the source of water. Removing the source of moisture through repairs or dehumidification is critical to preventing mould growth.

How can mould affect your health?
Moulds produce aerially dispersed spores (reproductive bodies similar to seeds) and chemical substances such as volatile organic compounds (VOC's). The substances produced by fungi that bring about a toxic response are called mycotoxins and are usually contained in the spores. Exposure routes include inhalation, skin absorption through direct contact with mouldy materials, or accidental ingestion.

Most types of mould that are routinely encountered are not hazardous to healthy individuals. However, exposure to high concentrations of mould may cause or worsen conditions such as asthma, hay fever, or other allergies. Some of the most common symptoms of over exposure are cough, congestion, runny nose, eye irritation, and aggravation of asthma. Depending on the type of mould, the level of exposure, and a person's individual vulnerability; more serious health effects such as fevers and breathing problems can occur.

Moulds can also cause serious infections such as Aspergillosis and Legionnaires' disease in immunocompromised patients. As a result, the Canadian Standards Association has published a document entitled "Infection Control during Construction or Renovation of Health Care Facilities" to prevent patient exposures to hazardous moulds.

How can I tell if I have a mould problem?

a) Visual Inspection
A visual inspection for mould growth should in done in any area where "potential" contamination is possible (i.e. where water and a food source are present) such as on ceiling tiles, behind wallpaper, behind drywall, underneath carpets , in HVAC systems and on pipe insulation. The mould may be any colour: black, white, red, orange, yellow or violet. Dab a drop of household bleach onto a suspected spot. If the stain loses its colour or disappears, it may be mould.

b) Smell/Odour
Sometimes moulds are hidden and cannot be seen. A musty or earthy smell often indicates the presence of moulds. However, a smell may not be present for all moulds.

c) Sampling
There are three forms of sampling commonly used in mould investigations; bulk, surface and air.

Bulk samples are collected from visibly moulded surfaces by scraping or cutting materials with a clean tool into a clean plastic bag.

Surface samples are collected by wiping a measured area with a sterile swap or stripping the suspect surface with clear tape. In both cases, the samples are normally diluted and a specific volume (aliquot) is distributed over a sterile growth media. After a suitable growth period the colonies are identified and counted. The results are reported in colony forming units (CFU) and percentages of each organism type present. The results can also be expressed in terms of CFU per gram of material or CFU per square centimeter of area sampled.

Air sampling requires the use of a devise to impinge organisms from a specific volume of air onto a sterile agar growth media. The sample is then incubated and the results expressed in CFU per cubic meter of air. Airborne mould spores can also be collected on a filter media and identified through microscopic analysis.

What should I do if I have mould growth?
In all situations, the underlying cause of water accumulation must be rectified or fungal growth will reoccur. An immediate response (generally within 24 to 48 hours) and thorough clean up, drying, and/or removal of water damaged material will prevent or limit mould growth. If the source of the water is elevated humidity, relative humidity should be maintained at levels below 40% - 60%.

It is recommended that porous materials such as furniture, ceiling tiles, plaster/lath, gypsum wallboard, and carpet, that have become wet due to floods, roof leaks, sewage backup and groundwater infiltration be discarded. Only in exceptional cases, and within 24 to 48 hours, should these materials be considered for drying and disinfecting.

There are several guidelines available to determine the proper procedures to be followed to remove mould growth. These are all based on the New York City protocol entitled "Guidelines on Assessment and Remediation of Fungi in Indoor Environments". The procedures are based on the amount of mould present as follows:

Level 1 Procedures - 10 sq. ft. or less
Level 2 Procedures - 10 sq. ft. to 30 sq. ft.
Level 3 Procedures - 30 sq. ft. to 100 sq. ft.
Level 4 Procedures - greater than 100 sq. ft.
Level 5 Procedures - Remediation of HVAC systems

A Level 1 clean up can be done by a homeowner or maintenance staff using an unscented detergent solution or, in the case of mouldy drywall, baking soda and a bit of detergent. Safety glasses, a disposable dust mask and household rubber gloves should be worn.

Level 2 to Level 5 clean ups should only be done by individuals or contractors with the proper training and equipment in order to avoid wide spread contamination of the building with airborne mould spores. In some cases, a health and safety professional with experience performing microbial investigations should be consulted prior to commencement of remediation activities to provide oversight for the project.

How can Power Environmental help me?
Power Environmental has many years of experience providing mould investigations, remediation and contracting services. This includes the provision of infection control for health care facilities and worker training.