Mould in your home

Mould in your home

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What is mould?

Mould is a type of fungi and belongs to a group of organisms that also include mushrooms and yeasts. Mould is present at low levels virtually everywhere, both indoors and outdoors.

People are exposed to mould on a daily basis without harm.

Mould looks like fuzz, or a stain or smudge and most commonly they are black, green or white in appearance. They can produce a musty smell.

Mould needs a food source (dirt, dust, wood, organic matter) and moisture to grow. Mould growth typically occurs in wet or moist areas that are poorly ventilated.

Mould reproduces by making spores. These spores can travel through the air when mould is disturbed (eg during cleaning) and when they land on damp spots, they may continue to grow and spread.

There are many different types of mould and some have the potential to cause health problems in people who are sensitive or allergic to them.

What are the health effects of mould?

Most moulds are not hazardous to humans and most people will not experience any health problems from coming into contact with mould.

Some mould spores however, may cause health problems when inhaled by people who are sensitive or allergic to them.

Typical health effects include coughs, runny or blocked nose, sneezing, skin and eye irritation, and wheezing.

For individuals with allergies such as hayfever and asthma, inhaling mould spores may trigger allergic reactions.

Very occasionally, mould may have more serious effects in people who suffer from respiratory diseases and in those who are immuno-compromised.

Who is at greatest risk of health problems?

People with asthma, allergies, or other respiratory diseases are more sensitive to mould. People with weakened immune systems (such as HIV infection, chemotherapy patients, or organ transplant patients) are more at risk of a mould infection in their respiratory system.

You should seek medical advice if you are concerned about the effects of mould.

Mould growth after a flood

If a building has been flooded for more than two days or there is visible water damage or musty odours following a flood, then you can assume that the building’s interior is contaminated with mould.

To prevent the mould from spreading it is important to clean up and dry out the house as quickly as possible, within 24 to 48 hours.

Open doors and windows to let house-air out for as long as possible.

Preventing mould

Mould can only grow where there is moisture, so the key to preventing mould is to reduce dampness in your home. Parts of a house that are prone to mould growth are:

  • Kitchens, bathrooms and laundries – due to condensation or high humidity
  • Cupboards and corners – due to restricted ventilation
  • Walls and ceilings – due to ineffective insulation
  • Walls and floors that are subject to rising damp as a result of inadequate damp proof coursing.

Mould growth can be prevented or minimised by using heat, insulation and ventilation.

Heat – a continuous, low level of dry heat will allow warmth to penetrate the walls and ceilings, keeping them dry.

Insulation – insulated walls and ceilings stay warmer, keeping the heat in and reducing condensation.

Ventilation – opening a door or window reduces moisture and humidity, both of which are required for mould growth.

All areas of a house should be regularly ventilated. Use exhaust fans when bathing, showering, cooking, doing laundry or drying clothes.

You can also reduce mould growth by:

  • Opening curtains and blinds during the day
  • Wiping away condensation on windows and windowsills
  • Clean and dry surfaces that get wet regularly (eg bathroom tiles)
  • Install exhaust fans in areas that are prone to condensation
  • Ensure all exhaust fans are vented to the outside air
  • Use lids on saucepans to reduce moisture
  • Keep rooms uncluttered to allow air movement
  • Hang wet clothes outdoors
  • Keep the roof, cladding and guttering in good repair to prevent leaks
  • Install exhaust fans in areas that are prone to condensation
  • All exhaust fans should be vented to the outside air.

Removing mould

If you can see or smell mould, you need to clean it up to prevent it from spreading and to prevent it from damaging the surfaces it grows on.

People who should avoid mould clean-up and avoid being present during clean-up include:

  • Children under 12 years
  • Pregnant women
  • People over 65 years
  • People with allergies and respiratory conditions such as asthma
  • People with weakened immune systems such as HIV infection or chemotherapy patients.

Small areas of mould can be cleaned by using mild detergent or a vinegar mixture (four parts vinegar to one part water).

If the mould is not readily removed, use diluted bleach (one part bleach to three parts water).

When cleaning mould, do not dry-brush the area as you may disperse mould spores into the air which may cause health problems or establish growth in other areas.

Wear rubber gloves, safety glasses and make sure the area is well-ventilated.

Absorbent materials such as carpets, upholstery and mattresses need to be discarded if they are contaminated with mould.

If mould contamination is extensive then a professional cleaner should be consulted.

Mould in your rented house

If you rent your home and have taken measures to ensure the building is properly heated and ventilated, and mould is still growing, you should raise the issue with the owner or real estate agent.

Mould can be a cause of unhealthy living conditions. Environmental health officers can inspect dwellings to assess risks to public health from occupying those dwellings, including the risks from mould.

Under the Public Health Act 1997, environmental health officers can serve notices and orders so that problems are addressed.

Tenants can find further information in the Tenants' Union of Tasmania Mould Fact Sheets or call the Tenants Union of Tasmania on 1300 652 641.

Public housing tenants can find further information at Damp, Condensation and Mould,  Housing Tasmania - Information for Tenants or call Housing Tasmania on 1300 665 663.

Mould in your workplace

Where mould at a workplace presents a hazard to employees the employer has a duty of care to control this hazard as far as is reasonably practicable under the Work Health and Safety Act 2012.

When an employee reports health effects which may be related to mould the employer has an obligation under the Work Health and Safety Act 2012 to investigate the employee’s concerns and advise the employee of actions to be taken to address the matter.

The Work Health and Safety Act 2012 requires employers to eliminate or minimise health and safety risks as far as is reasonably practicable by identifying the hazard, assessing the risk of harm to health, and considering suitable controls.

Further information

Further information is available from your council environmental health officer.

Testing for mould in your home: it is generally not necessary to test for mould in the home, as most mould is visible.

However, if you think you have mould in your home but cannot find the source of the problem or if you have tried to prevent mould from growing but are still having problems, you could employ an occupational hygienist.

For a fee, these professionals can provide specialist mould testing and consultancy services.