Last updated by Dr Sarah Brewer on
Indoor allergies have become increasingly common, and an estimated one in 10 people now suffer from indoor mold allergy. In people attending allergy clinics, as many as one in five are diagnosed with symptoms of mold allergy.
Symptoms of mold allergy
An allergy is an exaggerated immune reaction to foreign proteins, known as allergens. When you have a mold allergy, immune reactions against mold proteins are triggered by a type of antibody called immunoglobulin E. IgE binds to mold allergens that have entered the body in an attempt to neutralise their effects. This activated IgE interacts with mast cells in the lining of the airways, telling them to release histamine to flush the irritation away. But when you have a mold allergy, your mast cells release excessive amounts of histamine which produce the physical symptoms of mold allergy.
The symptoms of mold allergy include swelling of the nasal lining and sinuses producing the cold-like symptoms of an allergic rhinitis – stuffiness, sneezing and increased production of phlegm.
Histamine can also trigger swelling and spasm of airways in the lungs, causing coughing, wheeziness or severe breathing problems with worsening asthma. Sensitivity to airborne molds is not only more common in people with asthma, but is also recognised as a risk factor for developing asthma.
When mold spores come into contact with the eyes, allergic conjunctivitis results in soreness, itching and watering.
If mold spores sensitise the skin, you may develop redness, itching and eczema-like symptoms or contact dermatitis.
All these symptoms of mold allergy will be worse in a damp, moldy environment.
In people who are vulnerable, such as infants, the elderly, or those with long-term lung conditions or reduced immunity, molds can cause bronchitis, pneumonia and even lead to sepsis and meningitis, although this is rare.
Could you have a mold allergy?
Fungal allergy is often missed as a cause of allergy symptoms, as it can occur together with other common causes of allergy such as house dust mites, animal dander, grass or tree pollens. In fact, many people with a mold allergy also have specific IgE antibodies to other inhaled allergens, and having a mold allergy can further activate the immune system to enhance inflammation caused by other unrelated allergies such as hay fever.
If your symptoms are worse during autumn and winter, or occur all year round, you may well have a mold allergy.
Fungal mold spores are the most numerous air-born biological particles in the atmosphere, and are present in concentrations that are seventy-five times higher than pollen grains!
Outdoors, the number of mold spores in the air rises rapidly in spring, increases during summer and reaches a maximum in autumn before falling again during winter.
Some species of mold have a short season, such as ‘loose smut’ and powdery mildew’ while others such as grey mold and shadow yeast produce spores over a wider time range.
The same mold spores found outdoors occur indoors, and are a common cause of nasal allergy.
Indoor mold allergy
Outdoor mold spores enter the home and take root wherever moisture is trapped in the air, to grow all year round.
Common spots for mold to form are in bathrooms and kitchens but mold can also grow in the soil of indoor pot plants, on wallpaper, wall tiles, carpets and window frames, on books and clothes.
The moulds most often found in homes include species of Penicillium, Aspergillus, Cladosporium and Alternaria.
Most molds grow best within the temperature range of 18 to 32 degrees Centigrade. The level of atmospheric moisture affects their growth and spore counts rise in damp, dark conditions.
Levels of mold spores within a typical bedroom are only around five times lower than those found outside, and symptoms due to indoor mold allergy are increasingly common.
When the indoor air is disturbed by dusting, making beds, brushing floors, or any building works, the mold spore count increases by up to 17-fold, but then falls back to normal after the activity stops.
Here’s some mold I photographed in the bathroom of a supposedly ‘top’ hotel in London recently:
Devices are now available to test the quality of your indoor environment to help you ensure it stays damp-free to discourage mold growth.
Test your air quality in the home with Awair
Awair is a device developed to help people with allergies, and tracks levels of room temperature, humidity, carbon dioxide, volatile chemicals and particles such as dust.
Awair will tell you if a room is too humid and provides feedback that helps to improve allergies, asthma, eczema and sleep quality.
Awair Glow plugs into the wall and can automatically switch on non-smart devices, such as an humidifier or heater, as soon as your air quality drops. This is invaluable for keeping mold growth to a minimum.
You can see your air quality score on your device or on an app, and track improvements over time. A colour coded scale lets you know how healthy your air quality is, on a scale from 0 (poor) to 100 (healthy).
Awair products also connect with smart products like Nest, Amazon Echo, Google Home and IFTTT to automatically optimise your air throughout the day.
For example, Awair can tell Google Home to turn on a humidifier or a heater. It can also communicate directly with Amazon Echo allowing you to ask Alexa about humidity and other air quality factors in a room, and turn on Awair Glow.
The Awair unit features North American walnut timber for a traditional yet modern look.
Test your air quality in the home with Foobot
Foobot is the latest indoor air quality monitor developed to help people with indoor allergies.
Foobot helps you take control of your indoor air quality by constantly measuring levels of volatile chemicals, particulates such as dust, carbon dioxide, temperature and humidity.
Foobot provides warnings and advice to help keep your air in the home fresh and pollution free. Advice can be as simple as opening a window but with Foobot you’ll know exactly when it’s required and for how long.
Foobot also works with other smart home devices and connected thermostats, including ecobee, Honeywell, IFTTT, LUX and Google Nest to control your home’s temperature, and trigger ventilation, filtration, purification system or appliances.
Foobot can also communicate directly with Amazon Echo when any factors exceed healthy levels, allowing Alexa to talk about the problem and suggest possible solutions.
The Foobot has a modern, sleek design, and uses beautiful LED lights to discreetly indicate your air quailty at a glance.
Air purifiers for the home
An air purifier with a HEPA filter will remove 99.97% of airborne particles (as small as 0.3 microns) such as mold spores, bacteria, viruses, dust, pollen and other allergens – even cigarette smoke – so you breathe cleaner air.
An air purifier in the home will improve symptoms of mold allergy and asthma, as well as house dust mites allergies and hay fever.
Select the correct size of air purifier for the size of your room. A small air purifier is typically designed for rooms up to 8m2 – perfect for a child’s bedroom. A medium strength air purifier will cope with larger family room or living space up to 18m2, while the most powerful air purifiers can keep a shared living space up to 28m2 free from mould spores and other allergens.
The Fellowes’ range, which I use, have blue, amber and red lights to indicate the purity of the air being filtered, and allow you to increase airflow by 35% to 50% during peak allergy conditions.
Dehumidifiers reduce mold spore growth
Your home will accumulate damp for many reasons from boiling a kettle and cooking, to having a shower, drying your washing indoors, and using a steam iron. What’s more, every time you breathe, you exhale water vapour into the room. These all create a moist atmosphere and condensation in which mold can thrive.
Removing moisture from the air will prevent mold from growing. You can do this by creating less moisture in the first place and by using a dehumidifier.
As well as removing moisture, many dehumidifiers also clean the air using ionisers and silver-nano anti-bacterial and mold filters.
Use a catalytic fragrance lamp
A catalytic fragrance lamp, also known as a perfume lamp, effusion lamp or catalytic lamp, disperses scented oil into your home, using a heated stone attached to a cotton wick.
This form of catalytic combustion was originally developed by a 19th century French pharmacist for use in hospitals and mortuaries to neutralise the molecules associated with bad smells such as molds.
Once lit, a catalytic fragrance lamps does not operate with an open flame. After lighting the stone burner at the mouth of the lamp, you blow out the flame after a few minutes, once the stone is glowing, and the burner remains active at a low-temperature to diffuse aromatic cleansing scents into your room.
While air fresheners and room sprays just mask odours, a catalytic fragrance lamp actually purifies and cleanses the air before perfuming it, converting unwanted odours into harmless substances such as carbon dioxide and water (make sure you also use a dehumidifier if damp is a problem). Research shows that effusion lamp technology can even remove allergens, with over 60% of mould spores eradicated after 90 minutes exposure, along with 99% of dust mites and bacteria.
A wide selection of gorgeous catalytic lamps are available, together with fragrances that scent your environment while having a therapeutic effect.
Use anti-fungal bedding
Some anti-allergy duvets and pillows include defensive technology that kills and repels allergens, including moulds, using anti-fungal fibres and anti-microbial treatments. These materials create a durable barrier that eliminates mildew, bacteria and dust mites from your bed.
Anti-allergy bedding adds an extra layer of protection to help ensure a more fresh and hygienic sleeping environment. These new ranges of pillows, duvets and mattress protectors help to protect against night-time allergies and asthma attacks. As a result, some have received an Allergy UK seal of approval, as they help to prevent mould and fungi from entering the bedding, as well as dust mites.
To avoid mold forming in your home, and to prevent symptoms of mold allergy, it’s important to prevent damp.
- Open windows to air the home on dry, sunny days.
- Don’t dry wet clothes on radiators or indoor clothes racks – use a tumble drier that condenses extracted moisture, or channels it outside your home.
- Use an efficient extractor fan in problem areas such as kitchens or bathrooms to keep the atmosphere dry.
- Use an HEPA air purifier to filter air and remove mold spores.
- Use a dehumidifier to keep your home free from excess humidity.
- Remove patches of visible mold using fungicides or bleach.
- When decorating, using mold-resistant paints.