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Mould growth in your home can be unsettling. Blackened spots and dusty patches on the walls are signs that something is amiss, but it is important to distinguish between mould growth that is a nuisance and mould growth that may be harmful. There are more than one million species of fungi.
Some are used to produce important medications. Others can cause life-threatening infections when they grow in the body. Microscopic fungi that grow in homes are a problem because they can trigger asthma and other allergies.
In my work as a fungal biologist , however, I have yet to encounter robust scientific evidence to support claims that indoor moulds are responsible for other serious illnesses. What are moulds? Moulds are microscopic fungi that grow on everything. This may sound like an exaggeration, but pick any material and a mould will be there, from the leaves on your houseplant to the grain in your pantry and every pinch of soil on the ground .
They form splotches on the outside of buildings, grow in crevices on concrete paths and roads, and even live peacefully on our bodies. Moulds are important players in life on Earth. They’re great recyclers that fertilise the planet with fresh nutrients as they rot organic materials.
Mildew is another word for mould. Fungi, including moulds, produce microscopic, seed-like particles called spores that spread in the air. Mould spores are produced on stalks.
There are so many of these spores that you inhale them with every breath . Thousands could fit within the period at the end of this sentence. When these spores land on surfaces, they germinate to form threads that elongate, and they branch to create spidery colonies that expand into circular patches.
After mould colonies have grown for a few days, they start producing a new generation of spores. Where do indoor moulds grow? Moulds can grow in any building. Even in the cleanest homes, there will be traces of mould growth beneath bathroom and kitchen sinks.
They’re also likely to grow on shower curtains, as well as in sink drains, dishwashers and washing machines. Moulds grow wherever water collects, but they become a problem in buildings only when there is a persistent plumbing leak, or in flooded homes . There are many species of indoor moulds , which an expert can identify by looking at their spores with a microscope.
The types of moulds that grow in homes include species of Aspergillus and Penicillium , which are difficult to tell apart. These are joined by Cladosporium and Chaetomium , which loves to grow on wet carpets. Stachybotrys is another common fungus in homes.
I’ve found it under plant pots in my living room. When does mould growth become a problem? Problematic mould growth occurs when drywall becomes soaked through and mould colonies develop into large, brown or black patches. If the damaged area is smaller than a pizza box, you can probably clean it yourself .
But more extensive mould growth often requires removing and replacing the drywall. Either way, solving the plumbing leak or protecting the home from flooding is essential to prevent the mould from returning. In cases of severe mould growth, you can hire an indoor air quality specialist to measure the concentration of airborne spores in the home.
Low concentrations of spores are normal and present no hazard, but high concentrations of spores can cause allergies . During air testing, a specialist will sample the air inside and outside the home on the same day. If the level of spores measured in indoor air is much higher than the level measured in the outdoor air, moulds are likely growing somewhere inside the home.
Another indication of mould growth inside the home is the presence of different kinds of moulds in the outdoor and indoor air. Professional air sampling will identify both of these issues. Why are indoor moulds a problem? Indoor moulds present three problems.
First, they create an unappealing living space by discoloring surfaces and creating unpleasant, mouldy smells. Second, their spores, which float in the air, can cause asthma and allergic rhinitis, or hay fever . Finally, some moulds produce poisonous chemicals called mycotoxins .
There is no scientific evidence linking mycotoxins produced by indoor moulds to illnesses among homeowners. But mycotoxins could cause problems in the most severe cases of mould damage – usually in flooded homes. Irrespective of mycotoxin problems, you should treat mould growth in these more severe situations to prevent allergies.
The mould called Stachybotrys has been called the toxic black mould since its growth was linked to lung bleeding in infants in Cleveland in the 1990s. This fungus grows on drywall when it becomes soaked with water and produces a range of mycotoxins . Black mould spores are sticky and are not blown into the air very easily.
This behavior limits the number of spores that anyone around will likely inhale, and it means that any dose of the toxins you might absorb from indoor mold is vanishingly small. But the developing lungs of babies and children are particularly vulnerable to damage. This is why it is important to limit mould growth in homes and address the sources of moisture that stimulate its development.
Knowing when indoor moulds require attention is a useful skill for every homeowner and can allow them to avoid unnecessary stress. Nicholas Money is Professor of Biology, Miami University (This article is republished from The Conversation under a Creative Commons license. Read the original article here ) Published - November 24, 2024 07:00 am IST Copy link Email Facebook Twitter Telegram LinkedIn WhatsApp Reddit health / water / house building / Allergy and Immunolog.
