​​​​​​​​​​​​​​​​​​​​What is mould?

Mould is a type of fungus found outdoors and inside buildings. There are many kinds of mould, and they all need water to grow.

Mould spreads by releasing tiny spores and fragments into the air. These spores and fragments are so small you can only see them with a microscope. If they land on a surface with moisture or a food source, they can grow large enough to see.

Can indoor mould cause health problems?

People are exposed to mould, indoors and outdoors, every day. 

Usually, low levels of mould don't make you sick. But spending time in buildings that have problems with moisture or mould may lead to health problems.

Mould can affect people differently. How it affects you depends on the type of mould, the amount of mould, and your overall health.

What kinds of health problems are associated with mould?

Mould in buildings is associated with health problems such as:

• asthma flare-ups
• itchy, red, or painful (irritated) eyes, nose, and throat
• stuffy nose and blocked sinuses
• itchy skin or rashes
• breathing problems (such as wheezing)

Babies, older adults, people with breathing problems, and people with mould allergies are more likely to have health effects from indoor mould.

People with a weaker immune system can sometimes get a fungal infection from mould, but it is rare.

If I have symptoms, does it mean I have mould in my home?

Having symptoms associated with indoor mould doesn't always mean you have mould in your home. Other things can cause similar symptoms, including:

• pet or animal dander
• seasonal pollen
  
• indoor dust mites
• dust or particles
  
• second-hand smoke
• emissions (gas or particles) from fuel-burning appliances like wood gas stoves
  
• emissions from products like cleaning products, cosmetics, and air fresheners