What are the harmful effects of mould?

In this article, we’ll be discussing the harmful effects of mould.

First of all, what exactly is mould?

Mould is a type of fungi that are naturally occurring organisms playing a major role in the ecosystem of the earth. There are many types of mould out there in nature and here’s the 7 most common types of mould, but the one that we’ll be talking about is household mould as it poses the greatest threat to us humans.

Where does mould grow?

Mould grows best in damp, humid and poorly ventilated areas, and reproduces by making spores as it is a type of fungi.

Mould spores are present virtually everywhere, indoors and outdoors and are present in every human habitat. They’re airborne, light, and are individually invisible to our naked human eyes.

It’s impossible to get rid of all of them, and they generally do not pose a threat to you and your household. Generally, they grow in and on materials such as old food, fabric furniture, behind and on top of walls, paper and household plumbing. 

Mould spores under a microscopic view.

So, why is mould dangerous to you?

This article will be split into two parts – firstly, the harmful effects of mould on your health, and secondly the damaging effects of mould on homes and workplaces.

Harmful effects of mould on health

Firstly, let me start off by saying that most moulds are not overly detrimental to your health, and reactions to moulds can vary between individuals.

Minor allergic reactions are the most common health effect with most individuals when it comes to most moulds, but some people with severe allergies may suffer longer lasting and more severe health issues when it comes to mould.

Hence, it’s best not to take mould lightly, as you don’t exactly know how you may react to certain mould types.

If you are exposed to mould for a long period of time, you may suffer these effects:

  • Nasal and sinus congestion, runny nose
  • Respiratory problems, such as wheezing and difficulty breathing
  • Chest tightness
  • Cough
  • Nasal drip (Where mucus drips into your throat)
  • Throat irritation
  • Sneezing / Sneezing fits
A helpful diagram on what mould does to your health.

This is not an exhaustive list of symptoms, but they are the most common ones. In addition to this, if you have infants or young children at home, be on guard for a common fungal mould called Penicillium.

The Penicillium mould has been shown to cause an increased probability of developing respiratory symptoms such as asthma during their first year of life. Signs that an infant may have mould-related respiratory problems include (but are not limited to) a persistent cough and/or wheeze.

Hence, it’s best to remove mould as soon as you detect it.

Now, we’ll talk about the detrimental effects of mould on your household.

Harmful effects of mould on your household

To understand the harmful effects of mould on your household, we first need to understand how mould gets into our houses in the first place.

Mould spores make their way into the home either through the air or by attaching themselves to people, objects, or pets. (They’re awfully good at clinging on to pet fur!)

Open windows, doorways and ventilation systems are all ways mould spores tend to enter our houses, especially if we keep our windows open a lot here in sunny Singapore. In other words, anywhere there’s an opening into your house, you can be assured that mould spores are travelling through it.

However, there’s no need to be overly worried as mould spores only cause an issue if they meet the idea conditions for growing (warm, humid, dark, etc). Otherwise, they are generally harmless.

What are the harmful effects of mould on your house if they manage to thrive, though?

When mould survives and thrives, it tends to grow in areas that are usually damp and warm, such as bathroom mats, food and wallpaper.

A mouldy bathroom mat.

Mold Growing On Walls


When mould grows in rooms, it tends to leave the room with a distinct musty, mildewy smell. Besides the unpleasant smell, you’ll likely notice bulging walls (if mould is behind them) and odd black or green stains on mould infected objects.

Some people brush these odd coloured stains off as dirt, since they look fairly innocuous and don’t seem immediately harmful. When they finally notice that their walls are strangely warped or bending at odd angles, the mould has gotten comfortably settled into their house.

If you have coloured wallpaper in your house, the mould may even appear in colours that you’ve never heard of – like purple, orange or even pink!

Additionally, if the air in the house feels strangely “damp”, or the walls have water stains or discolouration, that may mean that a mould infection is impending, but may not have fully taken root in your home yet.


Windows are also prone to mould as they tend to be the main pathways through which mould enters your home. If water starts collecting on your windows and it hasn’t been raining recently, it may be condensation.

Lots of condensation in your home is a good sign that your house has a high amount of moisture, which turns it into a breeding ground ripe for mould.

Mould On Clothing

Mould can also grow on clothing, and it often does without people realising it. If you’ve ever picked up a forgotten towel off the floor and sniffed that odd, musty sound, that’s mildew. Mildew is usually a white or grey substance that is powdery or fuzzy in texture, so your clothes may feel oddly powdery and seem discoloured when you look at it.

Here are some tips on how to prevent mould growth

In conclusion..

There’s no doubt that mould is rather dangerous to both your health and home.

Mould often causes various health issues that are usually respiratory in nature, but can affect some people more than others. If you’ve got a young child or an infant, they are at greater risk of developing asthma or respiratory issues, so it’s best to get mould cleaned up as soon as possible.

As for your home, mould often causes structural damage, and seems harmless until it’s too late and you’ll have to spend plenty of time and money to rectify weakened walls, damp windows and wash mildew smelling clothing. Inspect your house regularly for mould, and keep a lookout for mould odours, or odd looking patches on your walls and other fixtures. If in doubt, it’s best to call a mould professional to come check your issue out.

For a mould removal professional in Singapore, contact Zenith Lab now!

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