In many homes across New Zealand mould is just another one of those things we have to live with. It’s unsightly, it’s a constant feature of winter bathrooms, and no matter how well you clean it, it always comes back. It’s a hassle, but it’s not something to be overly concerned about, right? Wrong!

Far from being just an aesthetically displeasing stain, household mould can pose significant health risks, including allergies, sinusitis, dizziness, depression, immune system suppression, and, in extreme cases, death. Mould should, therefore, be treated swiftly and thoroughly to protect the health of your family.

Dangerous Fungi

Moulds are microscopic fungi that grow on a host surface, deriving their nutrition from the breakdown of organic matter. In nature this ability of moulds to decompose matter plays a vital role in the environment. In a house, however, moulds pose a threat as they release dangerous spores into the air as part of their reproductive process.

There are many different types of mould – among the most familiar are the black moulds that creep across ceilings and bathroom walls, and the grey-green powdery moulds that grow on shoes and leather goods that have been left unused in a wardrobe too long.

Permanent Damage

Besides their negative influence on health, moulds can also cause damage to property and possessions. Left untreated, a mould infestation may permanently mark or discolour an item or surface – sometimes to the extent that certain building materials (Gib board, for instance) may need to be replaced.

Contributing Factors

Mould grows when mould spores land on a surface which provides the right conditions for survival. Prime among these conditions is dampness – in fact, mould cannot grow without moisture.

So, and it’s no secret to any householder, the most effective defence against mould is a reduction in the moisture levels in your house. And one of the most effective ways of doing this is by reducing the level of relative humidity in your home (relative humidity is defined as: the ratio of the amount of moisture in the air at a given temperature to the maximum amount of moisture it could hold at that temperature).

A relative humidity of around at least 65% – 70% is necessary for mould to grow. Keeping your home below 60% relative humidity will help retard mould growth, but ideally, to really make an impact, humidity should be kept between 30% – 50%.

Reducing Relative Humidity

There are a number of measures you can take to reduce the level of humidity in your home. These include:

  • Use a dehumidifier and monitor relative humidity with a humidity meter (available at most hardware shops).
  • In summer, use an air conditioner as it will remove moisture from the air (remember to keep air conditioner drip pans and drain lines clear).
  • Where possible, vent moisture-producing appliances outside the house (clothes dryers, heaters etc.).
  • Use an exhaust fan when cooking or running large appliances in the kitchen.
  • Use an exhaust fan or keep the windows open when showering or bathing in the bathroom.

Other Moisture Reducing Measures

In addition to drying out the air in your home, there are several other things you can do to lower general levels of dampness.

  • Fix water leaks as soon as possible.
  • Sponge up condensation on windows and window sills whenever it occurs.
  • Ensure adequate ventilation.
  • Keep your gutters clean so that water does not accumulate in them.
  • Insulate cold surfaces such as cold water pipes.
  • Increase the general air temperature in the house.

Cleaning Mould

Ok, prevention is all very well, but you’ve got ugly black blotches all over your bathroom wall and you want to know how to get rid of them. The good news is that although it requires a bit of elbow grease it isn’t complicated.

First of all, precautions. To avoid the negative health consequences of inhaling mould spores you should take adequate protective measures, particularly if you are cleaning a large or heavy infestation. These precautions might include wearing non-ventilated goggles, a breathing mask and protective gloves.

There are plenty of mould cleaners on the market, but you can save yourself some money by using the cheap household alternatives below.


  1. Scrub the area with a non-ammonia detergent solution or multi-purpose cleaner.
  2. Disinfect using a solution of 1 cup of bleach to 4 litres of water. Note: don’t mix bleach with ammonia-containing cleaning products as bleach reacts with ammonia to produce toxic fumes.
  3. Rinse and dry promptly to avoid elevating moisture levels.

If you are in a hurry you can skip steps 1 and 3 and just rub the area down with the bleach solution. This will remove a lot of the mould, though it may not remove staining from some surfaces.


  1. Scrub the area with a detergent solution or multi-purpose cleaner.
  2. Wipe the surface down with neat white vinegar.
  3. Do not rinse (unless you find the smell overpowering).

Vinegar is an effective anti-mould agent and has the advantage of being more environmentally friendly than bleach or commercial mould cleaners.

Health Issues

A final note, just in case you think breaking out the scrubbing brush is too much work.

Though exposure of healthy human beings to low levels of mould does not generally result in life-threatening consequences, the health impact can be significant.

Mould can provoke immune responses in certain individuals – symptoms can include coughing, sneezing, runny nose, burning eyes, sinusitis and the provocation of asthma.

As mould breaks down organic matter to feed on it produces volatile organic compounds (VOC). VOCs may irritate the central nervous system and result in headaches, impaired concentration, dizziness and depression.

Moulds also produce metabolic by-products called mycotoxins. These substances can be very dangerous to human beings and can cause fatigue, diarrhoea, immune suppression, nose bleeds and cancer.

Protect Your Family

An hour or so of time, a little exertion and the right choice of cleaning materials is all you need to get rid of mould and protect yourself from it’s harmful effects. Your home will look cleaner and brighter, smell fresher and, most importantly, it will be a much healthier place to live for you and your children.

Learn more about the dangers of mould in this video.

Mould - How to Protect Your Home from this Dangerous Fungus, 4.5 out of 5 based on 6 ratings

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  1. Marion Brown says:

    Don’t forget about the moss/mould, black grime & lichen on the exterior of your property these are also causing damage to your home. Mould Patrol uses a no pressure slow release cleaner that works with the elements. Check out our website or call us to stop mould from taking hold at your property.

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