Mold / Allergens

What is mold?

Molds are fungi that grow in damp environments. They play an extremely important role in the outdoor environment by breaking down dead organic materials and helping to maintain a healthy and productive environment. While there are more than 100,000 species in the outdoor air, only a small number grow/proliferate indoors. The presence of these molds in the indoor environment can adversely affect the health of the inhabitants, in addition to contributing to the decomposition of building materials and structural damage.

Molds reproduce by releasing spores which are carried by air currents to other surfaces, and if the environment has adequate humidity growth occurs.

Where can mold be found in the home?

Mold can be found inside walls, on ceilings/walls, in basements or other areas that have been exposed to water or are an area of high humidity.  These areas of growth are often consequent to leaks, flooding, or condensation.  Look carefully in any areas where there is a musty ‘earthy’ odour, or signs of staining or discolouration.

Most common building materials are capable of sustaining mold growth. Spores require four things to grow:

  • Moisture – The most limiting factor - moisture is required to initiate the decaying process and growth of spores into mold.
  • Nutrients – cellulose found in wood and paper (drywall backing) is an ideal food source, but it can grow on virtually any substance including carpet, wallboard and foods.
  • Time – mold can growth begin from between 24 hours and 10 days after provision of ideal growing conditions.
  • Temperature – between 5-35 degrees Celsius is optimal growing temperatures for most molds.

How can people become exposed to mold?

People are typically exposed to mold by inhalation of the spores and fungal fragments, but ingestion may also occur. When mold growth occurs within a building, occupants may be exposed to a much higher quantity of these spores than the outdoor air. 

What are the health risks of mold exposure?

Molds can produce allergens, irritants and potentially toxic substances. This becomes an issue in regards to human health when these substances become airborne and are inhaled or ingested. Exposure to molds can produce mild to severe reactions in humans. Mild symptoms of exposure can include eye and skin irritation, nasal congestion, rhinitis and wheezing. More severe reactions like fever and shortness of breath can occur in people with serious allergies to mold or workers exposed to large amounts of mold in occupational settings. Mold exposure has also been proven to trigger asthma attacks.  For the immune-compromised, these symptoms may all be more severe in addition to having the potential for acquiring opportunistic fungal infections.

What are allergens?

An allergen is a substance, usually a protein, which stimulates the production of an antibody that causes immediate hypersensitivity, otherwise known as an allergic reaction. In the case of dust mites, cockroaches and cats, the allergen is a protein they produce. Der p1 and Der f1 are the major allergens from the dust mite species Dermatophagoides pteronyssinus and Dermatophagoides farinae respectively. The primary allergen for a cat is a small stable protein, Fel d1, while one of the major German cockroach allergens is Bla g1.  These are what we test for when analyzing to detect for the presence of all associated allergens.

How can people become exposed to allergens?

We are exposed to allergens from mites and cockroaches primarily by the inhalation of fecal particles and the secretions they produce, these secretions can adhere to dust particles and become airborne in your home. Mite allergens have a lower tendency of becoming airborne and as a result exposure usually occurs while sleeping in direct contact with mite infested bedding. Cat allergens are found in the saliva and secretions coating their fur, these allergens can accumulate in furnishings as well as becoming airborne in very high levels.

What are the health risks of allergen exposure?

Mild to severe allergic reactions can be expected, from itching eyes and nose to difficulty breathing, wheezing and shortness of breath.  Allergen exposure has been implicated in a variety of diseases including asthma, sinusitis, conjunctivitis and rhinitis.  Development of childhood asthma has been associated with exposure to dust mite and cockroach allergens. The levels of allergens in the accumulated dust throughout a home can be significant to a doctor or allergist when trying to determine whether an individual’s level of exposure is significant.

Analysis for mold and allergens at Paracel

Paracel Laboratories Ltd. can test for a variety of molds and allergens and is fully accredited facility for mold analysis.  All of our analysts working with fungal cultures have been trained through the internationally recognized fungal identification course given by the Centraalbureau Voor Schimmelcultures. Allergen quantification is performed by Enzyme-Linked Immunosorbant Assay (ELISA), to detect specific individual allergens, as well as a Multiplex system that detects several allergens simultaneously.

Collecting samples for Mold or Allergen analysis

For mold, a small Loonie sized piece of contaminated building material in a food quality zip lock type of bag can be provided.  If a destructive sample like this cannot be collected, a tape or swab sample of the surface can also be collected.   Tape samples can be collected by pressing the center cm of a 3cm piece of transparent cellophane tape to a surface (or a prepared slide from the lab), removing without the actual building material surface, and smoothing gently into the inside of a food quality zip lock type bag.  A swab sample can be collected by inserting the lab supplied swab into its case to moisten the tip, then thoroughly rubbing this on the discoloured surface in question, then reinserting the swab in its case.

For allergen analysis, settled dust can be collected by thorough vacuuming with a specialized filter that slides over the nozzle of your vacuum.   Paracel can supply all of these necessary sampling materials and containers. 

What do I do if Mold is found in my samples?

Clean up – Removal - Prevention

Small areas of mold may be cleaned up by yourself. Refer to the links below for cleaning and preventative procedures. If there are large areas with significant mold amounts or suspected sewage backup, contact a professional consultant and/or mold abatement/removal service for an evaluation prior to starting any renovation work.

Simply put by the EPA, mold clean up and prevention basics include:

  1. The key to mold control is moisture control.
  2. If mold is a problem in your home, you should clean up the mold promptly and fix the water problem.
  3. It is important to dry water-damaged areas and items within 24-48 hours to prevent mold growth.

Additional information

Refer to the Web Links below for further information. Alternatively, inquiries can be submitted by completing the Information Request Form located on this web page. Our Service Team is available to answer any questions that you may have regarding your analytical requirements.


Government of Canada – Mold:


Canada Mortgage and Housing Corporation – Mold:

US EPA – A Brief Guide to Mold, Moisture and Your Home:

CDC – Mold and Dampness: