Mold in Your Home: Types, Health Risks and How to Protect the Air You Breathe

Is mould really dangerous?

When we see dark patches on a wall or in a corner of the bathroom, the most common reaction is to treat them as a simple cosmetic problem. The reality is quite different: mould is a living organism that releases spores and mycotoxins into the air, substances that can affect our health, often without us noticing.

In Italy, where the building stock is among the oldest in Europe and humidity is constant in many homes (from the Po Valley to the coast, from basements to attics), indoor mould is more widespread than people think.

Types of mould: not all are the same

There are thousands of mould species, but some are more common in homes and more relevant to health:

Spores and mycotoxins: what is the difference?

Mould causes health problems in two distinct ways:

• Spores are the "seeds" of mould: microscopic particles that float in the air and are inhaled. They mainly cause allergic reactions and respiratory problems.
• Mycotoxins are toxic chemicals produced by some moulds. In the air they travel mainly attached to spores and microscopic mould fragments, which can be much smaller than the spores themselves, and they can build up in the body over time. Added to these are the microbial volatile organic compounds (MVOCs) produced by mould, which cause its typical musty smell.

An effective air purifier must capture both, and this is one of the reasons why not all purifiers are equal when it comes to mould.

Where does mould grow at home?

Mould needs three conditions to develop: humidity, warmth and an organic surface to grow on. At home the highest-risk places are:

• Bathrooms and showers (tiles, silicone, curtains)
• Under sinks and behind fridges
• External walls with thermal bridges or poor insulation
• Basements and cellars
• Air-conditioning ducts and HVAC systems
• Mattresses, pillows and rugs in damp environments
• Behind furniture placed against cold walls

In many cases mould is not visible: it grows inside walls, in ducts, under floors. But the spores and mycotoxins it produces still circulate in the air we breathe.

How mould can affect health

The respiratory and allergic effects of mould (coughing, sneezing, rhinitis, asthma, irritation) are well documented by the WHO and EPA. Beyond these, research has hypothesised a range of more systemic effects: we report them with caution, because they do not all have the same degree of scientific evidence.

Possible effects on the brain

Some mycotoxins have been studied for their potential neurotoxicity. An association has been hypothesised with difficulty concentrating, memory problems, "brain fog", anxiety and sleep disturbances. Many people living in mouldy environments report this sensation, which tends to improve away from the contaminated space, although the causal link is not yet established with certainty.

Possible effects on hormones and metabolism

Some mycotoxins have been studied as possible endocrine disruptors. A correlation has been hypothesised with alterations in thyroid hormones, cortisol and insulin, and therefore with metabolism, weight and energy. These are areas still debated in the scientific literature.

Effects on the immune system

Continuous exposure to spores can keep the immune system in a state of activation. Some studies hypothesise that over time this may contribute to overactive responses or, conversely, to a weakening of the defences. Immunocompromised people (the elderly, children, cancer patients) are in any case recognised as more vulnerable.

Pain and inflammation

Some people associate mould exposure with symptoms such as joint and muscle pain, persistent headache and general malaise. These symptoms have many possible causes and are often attributed to other conditions: the correlation with mould at home is a hypothesis to investigate with a doctor, not a certainty.

Testing and remediation: what to do if you suspect mould

If you suspect mould at home, the first step is an environmental test. There are DIY kits to collect air or surface samples, but for a reliable assessment it is advisable to turn to a certified professional who can identify the species present and their concentration.

After a flood: the most critical case

A flood is the situation in which mould develops fastest and most extensively: walls, plasterboard, insulation and furniture stay soaked for weeks. Spores increase above all during the removal of wet materials, drying and renovation. A study of flooded homes in Cedar Rapids (Iowa, 2008) measured significantly higher concentrations of mould, bacteria and particulate matter in homes with work still in progress than in those already remediated. To find out what to do step by step, read our article on floods and indoor air.

Why not all purifiers work against mould

In its technical document on residential air cleaners, the US EPA (Environmental Protection Agency) identifies high-efficiency mechanical filtration, such as HEPA filters, as the most reliable method for particles, including spores, and activated carbon as the right medium for gases. The same document instead points out the limits and risks of other heavily marketed technologies:

The solution: Austin Air purifiers

Austin Air purifiers combine a medical-grade HEPA filter, for spores and mould fragments, with a large amount of activated carbon and zeolite, for odours and MVOCs. For mould, the starting point is the HealthMate®: according to Austin Air, the carbon in the base models also treats mould-related mycotoxins. Depending on the situation, there are targeted alternatives:

• Bedroom Machine®, for the bedroom, with the additional HEGA carbon cloth stage;
• HealthMate Plus®, if formaldehyde, paint or new furniture are also present besides mould;
• Immunity Machine®, for the most demanding situations or when people with heightened immune vulnerability live in the home.

Medical-grade HEPA filter: for spores

The medical-grade HEPA filter in the standard models, 60 square feet (about 5.6 m²), captures 99.97% of particles at 0.3 microns and 99% at 0.1 microns, sizes far smaller than mould spores (1 to 30 microns): this is why spores passing through the filter are captured very effectively.

Activated carbon and zeolite: for odours and MVOCs

The musty smell of mould comes from gaseous compounds, the MVOCs, which a HEPA filter alone cannot capture. These require activated carbon and zeolite, up to 6.8 kg in standard Austin Air models, which adsorb them together with the other VOCs in the air. According to Austin Air, the carbon in the base models also treats mould-related mycotoxins.

Conclusion: the air you breathe at home can make the difference

Mould is one of the most underestimated indoor air quality problems. Its respiratory and allergic effects are documented, and in Italy humidity and the age of buildings make it particularly widespread: having effective protection is a concrete health choice.

Austin Air purifiers, starting with the HealthMate®, combine medical-grade HEPA and high-capacity activated carbon: the two technologies the EPA identifies as the most suitable for particles and for gases respectively.

To learn more about how to choose the right purifier, read our complete guide to air purifiers.