Many people are suffering from symptoms and don’t know the cause. We live in a beautiful part of the world, but one of the things we put up with on the West Coast is moisture. If the moisture inside your house is high, this can lead to mould growth. Just because you have mould, does not mean it is making you sick. You need to find out how much you have and what kind it is. Also, is the mould invading your air space? 

  Mould will grow above 60% humidity. If you keep your home between 40-60% humidity, your chances of having mould will decrease. I have a wood stove, so in the winter my house is usually dry enough to keep the mould growth down. When I stop using the wood stove, the humidity in my house goes up. 

  There is mould outside that will find its way in. If conditions are right, it will grow. There can also be damp areas inside that can create the ideal living space for mould. 

  There are things you can do right now to decrease and prevent mould from becoming a problem:

  • Buy a humidity meter. If your humidity is consistently above 60%, you need a dehumidifier. 
  • Keep the dust down. Dust and pet dander create a place for mould to grow. 
  • If you are considering buying new carpets, consider hardwood flooring instead. The dust shows up and we tend to sweep more often than we vacuum. (At least, my husband does!) When you see how much dust has accumulated on the floor after only a few days and realize how much dust builds up in your carpet,  it is a good argument for installing hardwood. Also, carpets can off-gas formaldehyde for up to 10 years after you have installed them. When installing flooring, make sure to use non-toxic glue or buy click flooring, which doesn’t require any glue. 
  • If you see visible mould on window sills or walls, do not use bleach to clean it. This can create a more toxic environment. Bleach has been linked to the rising rates of breast cancer in women, reproductive problems in men, and learning and behavioural problems in children. Instead, mix 20 drops of Tea Tree oil (Melaleuca Alternafolia) with ½ cup of water. You can also use a 3-4% sodium carbonate (also known as soda ash or washing soda) solution in hot water. Clean area with scrub brush and mixture. Wear rubber gloves and a disposable mask. If sensitive to mould, hire a professional to clean it for you.

  Symptoms related to mould can include:allergies, asthma, and headaches, among others. Mould can also increase symptoms of Fibromyalgia and Multiple Sclerosis. 


Kyla Mortil, BBEC is a Building Biology Environmental Consultant.