Mould growth and your health

Moulds are fungi, like mushrooms, which are present at low levels both indoors and outdoors.

You are exposed to mould on a daily basis without any harm. Moulds need organic materials like wood, paper or dirt and moisture to grow. The most common moulds are black, green or white, although they can be other colours.

They can produce a musty smell and release countless tiny, lightweight spores which travel through the air. This happens when moulds are disturbed, such as during cleaning, or in dry conditions when a house or building is being dried out.

If mouldy materials are not removed or properly cleaned, high levels of airborne mould spores may be a health risk if you are sensitive.

You can be exposed by eating, inhaling or touching mould spores.

If you are sensitive to mould

Mould can trigger asthma attacks and make other respiratory and allergic conditions worse.

Symptoms depend on the amount of airborne spores you are exposed to, and how sensitive you are to moulds.

People who should avoid a cleanup or repair works include all of the following

  • children, especially infants
  • pregnant women
  • people over 65 years old
  • people with a weakened system, allergies, severe asthma, chronic obstructive or allergic lung disease.

Health effects of mould exposure

If you develop health problems after mould exposure you should get medical advice.

If you are sensitive to mould, any of the following can happen:

  • stuffy nose
  • irritated eyes
  • wheezing
  • skin irritation.

If you are allergic to mould, any of the following may happen:

  • difficulty breathing or shortness of breath
  • you may develop mould infections in your lungs if you have a weak immune system or have a chronic lung condition such as obstructive lung disease.

Testing for mould

You should assume that a building's interior is contaminated with mould if any of the following apply:

  • it has been flooded for more than two days
  • visible mould is growing
  • there is visible water damage
  • you can smell mildew.

If your building has been flooded you should clean up and dry out the house as soon as possible.

After a flood

If you are visiting your house to collect belongings, inspect the damage or do a basic cleanup over short periods you should wear sturdy, waterproof footwear that has rubber soles, and rubber or leather gloves.

If you are going to be inside the house for a long time or you are cleaning up mouldy areas, you should also wear a shower cap, goggles and a particulate respirator to prevent breathing in mould spores.

If you are asthmatic you should keep your medication with you. If you show signs of an asthma attack you should get immediate medical attention.

If you have had a flood in your home, you should do all of the following to minimise mould:

  • remove all pooled water or excessive moisture
  • remove all wet or flood damaged materials including wallpaper, plasterboard, carpet, rugs, bedding, mattresses, furniture, stuffed toys, clothing and anything else that can't be dried or cleaned
  • remove all soft or absorbent material
  • store damaged or discarded items outside of the home in a dry, clean place until your insurance claim is processed
  • clean and disinfect all surfaces including floors, walls, kitchen, bathroom and laundry
  • use a fan or dehumidifier to dry the house.

Wearing a respirator

You can buy special respirators called P1 or P2 for filtering out airborne mould spores from most hardware stores.

Ordinary paper dust masks and cloths do not usually filter out mould spores.

You should be aware of the following about respirators:

  • they can be hot and uncomfortable to wear
  • if the seal around the face is poor they will not work as well - for example, if you have a beard
  • it does not filter out gases like carbon monoxide
  • it can be harder for you to breathe normally, so if you have a heart or lung condition you should ask your doctor before using it.

How to remove mould

Step 1: clean

Household products usually work if used correctly. You should read the product's label to see how much and where you can use them, as well as warnings about what chemicals you can mix them with.

Clean one room at a time. You should use two buckets, one for rinse water and the other for the cleaner. This keeps most of the dirty rinse water out of your cleaning solution.

Rinse out your sponge, mop or cleaning cloth in the rinse bucket. Wring it dry and keep it rolled up tight when you put it in the cleaner bucket.

You can also try any of the following:

  • 70% solution of white wine vinegar with water - 1 litre of vinegar in 450ml water
  • 80% methylated spirits in water - 1 litre methylated spirits in 250ml water
  • 1.5 cups of household chlorine bleach in 10 litres of water.

Using bleach

You should never mix bleach with ammonia or any other cleaning product of detergent with ammonia.

Do not use a bleach-based solution on aluminium, stainless steel surfaces or linoleum. Use a household detergent.

Step 2: disinfect

Disinfect surfaces with a disinfectant product. Or you can use half a cup of household chlorine bleach in 10 litres of water.

Step 3: drying

Open the doors and windows and let the house air out.

If power is restored use fans and dehumidifiers to dry the house out.

Air conditioning or central heating should not be used if they are damaged or contaminated by flood waters.

If you suspect contamination, do not use until they have been cleaned and checked by a qualified person.

For more information contact Environmental Health.

Last updated: 10 April 2018

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