Mould is the No. 1 enemy of air quality in houses and can head to major health problems.  Irritation, coughing, shortness of breath, respiratory difficulties and many other symptoms are associated with mould.  Those with weakened immune systems are especially vulnerable, but anyone exposed to mould may end up with health problems because of it.

Where is it found? Mould grows in any humid environment.  It is commonly found in:

  • Basements
  • Bathrooms
  • Kitchens
  • Carpets
  • Laundry rooms


This colourless gas is an irritant that can cause a burning sensation in the eyes, nose and throat when someone is exposed to high concentrations, which, fortunately, is uncommon in living spaces. But be careful! Formaldehyde is insidious, as a person may develop allergies and respiratory problems if exposed over the long term to even just a moderate concentration of formaldehyde. 

Where is it found? Formaldehyde can come from many sources, specifically:

  • Tobacco smoke
  • Smoke from fireplaces or wood-burning stoves
  • Paint and varnishes
  • Wallpaper
  • Glue used in wood products such as furniture, closets, floors, etc.
  • Carpets

Carbon monoxide

This colourless, odourless gas is a major contaminant.  Low exposure to carbon monoxide can lead to headaches, fatigue and shortness of breath.  Long-term exposure can cause flu-like symptoms, as well as dizziness, vision problems and chest pain. 

Worst of all, carbon monoxide poisoning can be fatal. The danger of carbon monoxide is that this gas can pollute interior air and cause health problems even before it’s detected. 

Where is it found? The best way to prevent problems is by installing a carbon monoxide detector, and making sure you are using the following items safely and correctly:

  • Wood, charcoal and gas stoves
  • Fireplaces
  • Propane barbecues and ranges
  • Gas-powered tools

Never use products designed for outdoor use inside the house.  Don’t let your car idle in the garage.  And remember that tobacco smoke also contains carbon monoxide.

Other products that seem harmless can contaminate the air in your house and affect the health of its inhabitants.  Pay careful attention to aerosol products (hair spray, deodorants, air purifiers), perfumes and household cleaning products.