There seems to be a mould epidemic. We dig into why even sustainable houses are coming in for mould infections and what to do about this scourge when it hits.
In another article soon, we’ll delve more deeply into how construction and building materials play a part.
While an ever-present problem in houses, mould is becoming one of the biggest problems a household could face this winter – but reliable information on managing moisture and humidity is difficult to access, often imbued with many contradictions.
Bleach, for instance – some say it’s okay to use, and others absolutely warn against it.
According to NSW Health, mould is a common spore in the same family as fungi such as mushrooms and yeast. As spores, they are present everywhere, both indoors and outdoors, but physical mould outbreaks can occur on surfaces where moisture accumulates.
General symptoms of increased mould exposure could include runny or blocked nose, irritation of the eyes and skin, wheezing, asthma attacks and mould infections known as hypersensitivity pneumonitis.
In an interview with The Fifth Estate, building biologist and chief executive of the Australian College of Environmental Studies Nicole Bijlsma said symptoms could vary depending on the species of mould.
It could also lead to persistent upper and lower respiratory infections, such as tonsillitis, pharyngitis, bronchitis, and sinusitis, as well as symptoms similar to chronic fatigue or recurring colds and flues that don’t respond to treatment.
Starting off as a naturopathy and acupuncturist, Bijlsma noticed several clients, especially those with asthma, allergies, autoimmune disorders, and chronic fatigue, were not getting good results despite changing lifestyle and diet.
But it wasn’t until she had 10 miscarriages in her first home that she realised something was wrong and began to research building biology and hazards in the home. Since she moved out of her bedroom, she has gone on to have twins and a third child and had recently completed her PhD on environmental exposures.
Jodie Green, mould testing technician and founder of her business The Mould Lady, adds that mould could also lead to headaches and neurological problems such as anxiety, depression and cognitive impairment. While inhaling and touching mould are the main health issues, those with allergies and sensitivities can also experience additional symptoms.
Even new and sustainable houses have mould problems
While many believe that older homes and flood prone areas are more susceptible to moisture issues, to some extent, newer homes are now showing signs of deeper issues, Green says.
“They might do up this timber framing and leave it in the rain for however many weeks – and they’ll go and put all the walls on without checking that all the timber has reached a dry standard.”
Green says that new homeowners and renovators should talk to their builders during the construction phase about how they will manage water and rain and prevent mould. She added that even the design process should incorporate thoughts about condensation management.
“Sometimes in new construction, you’ve got products like MDF (medium density fibreboard) or plasterboards, which, when they absorb moisture, becomes a breeding ground for mould.
There’s a lot of fast construction, she says, that precludes careful consideration.
Green advises that homeowners and renovators consider getting a professional mould assessment to address any underlying moisture issues and consider building materials and furnishings less prone to mould growth.
Prachi Garnawat, founder of the ResearchBit newsletter and former RMIT researcher, says mould is most commonly found during winter on surfaces where warm air meets cold surfaces, causing condensation.
But she’s also found it in a sustainable housing project that she and her team initially consulted on for carbon dioxide monitoring.
Problems with mould often stemmed from a lack of occupant education on how to optimally maintain and ventilate a house, Garnawat said.
In the sustainable project, it was quite easy to explain to residents how to change their behaviour.
“The developers have used this feedback, so newer housing now has more mechanical [ventilation] systems integrated, and some are considering heat recovery systems.”
“Because these houses are new – Australia is not used to them – it can be challenging to manage,” Garnawat says.
“In Australia, we are used to leaky houses and windows, so people are not in the habit [of moisture management].”
So, where does mould typically appear?
A list, according to the experts, includes:
- bathrooms
- kitchens
- areas that have been flooded or damp and have not dried in 48 hours
- in air handling units and HVAC systems
- inside wall cavities, roof cavities and under floors – where there is moisture build up
- any rooms with poor ventilation or water leaks
- sub-floor spaces that are damp or with no air circulation
- textiles and fabrics that don’t dry in 48 hours
- laundry rooms from the evaporation of wet clothes
According to Jodie Green, mould can grow anywhere with high moisture and food sources, usually dust and organic materials, making unmaintained air conditioning and uncleaned windows with dirt a prime target.
“There’s no such thing as a mould free home,” Green says. “Humidity can be quite high in winter, and when it’s raining outside, it’s a surefire way to know that it’s very humid.”
But by heating our environment, we add to the humidity via the condensation that accumulates.
This includes longer and hotter showers, heaters, and cooking dinner, which is held as water vapour in the warm air but then becomes condensation when the temperature drops overnight and builds up on surfaces such as windows, walls and wardrobes.
“It creates the perfect little environment [for mould],” says Green.
However, according to Bijlsma, windows are only a small part of the problem as they are often small in areas. Instead, carpets are one of the biggest offenders.
“If the carpet gets wet and doesn’t dry within 48 hours, they can create worst mould that could impact people’s health – this is very big stuff that no one is talking about, especially in rentals.”
“They steam clean the carpet between tenants, but this could dramatically escalate their exposure to mould. When I remediated for a former cleanup specialist in Australia, they were saying, Nicole, we reckon at least 20 per cent of Airbnbs are contaminated because they are cooking within six hours [of carpet cleaning].”
According to Bijlsma, carpets become the “archaeological dig site” of a house, easily absorbing pollen, asbestos, lead paint, fungal particulates, flame retardants and other chemicals and have vermin potential. With moisture added to the mix, the dust on the carpet easily becomes feeding grounds for mould.
How do you prevent mould?
According to the three experts, a list of things both property owners and renters should ensure include:
- open the window for fresh air when outdoor humidity is low
- use or install exhaust fans in bathrooms and kitchens to remove moist air
- upgrade exhaust fans to vent directly outside and not into roof cavities
- run exhaust fans during and 30 minutes after showers to remove humidity
- regularly cleaning surfaces – especially where dust gathers to remove the chance of mould growth
- use dehumidifiers to control humidity levels and avoid humidifiers in damp or humid conditions
- regularly inspect and maintain air handling units and HVAC systems to prevent microbial growth
- ensure any water leaks or flooding issues are addressed promptly and dry within 48 hours
- buy a humidity monitor and ensure humidity levels below 60 per cent – ideally around 50 per cent
- regularly check and clean wardrobes, and if the heater or dehumidifier is on, open your wardrobes regularly to ensure your clothes are dry
- ensuring clothes are dried outside or in a vented dryer
- regularly clean and maintain gutters, downpipes and drainage systems to prevent moisture buildup
Ok, so mould is growing in my house; now what?
The first thing, says Green, is to not immediately spray the mould growth with bleach.
“Don’t use bleach; it doesn’t do anything because the active ingredient in bleach evaporates after so much time, and the water in bleach actually feeds the mould.”
The suggestion instead was to wear a mask and clean away any little bit of visible mould using diluted white vinegar with a damp microfibre cloth. “It might sound silly, but I had a lot of clients that are like, ‘Oh, we tried to clean it away, and we are so sick afterwards’.”
A NSW Health website, however, says to use mild detergent and, if that doesn’t work, diluted vinegar with a microfibre cloth. And if that doesn’t work diluted bleach or commercial products.
Advice to remediate mould includes:
- remove any porous materials like carpets that have been significantly affected by mould
- thoroughly clean and dry any affected areas within 48 hours to prevent further spread of mould
- stop any source of moisture or water leak that may be causing the mould growth
- if mould is in multiple rooms and covering more than one square metre, it’s likely a larger issue that requires professional assessment and treatment
- if you have allergies, avoid cleaning the mould yourself as it releases more mould spores. It’s best to have a professional mould remediation specialist for proper treatment
- be prepared that addressing a mould issue can be costly, as it often requires fixing the underlying moisture issue that caused the growth in the first place
- walls and surfaces may be removed or peeled off by professionals to remove affected materials
The consensus was that in addition to removing the mould, the key is to address the moisture or humidity that allows the mould to grow.