Introduction

Mould is a type of fungi that appears black or green and grows in damp or decaying items such as food, paper, wood or surfaces like walls. Mould can produce spores that contaminate the air, which can be inhaled and can cause an allergic reaction in some people. For a person with mould allergy, their immune system goes into attack mode after recognising the spores as harmful substances. In response to this, a chemical called histamine is released, which presents with allergy symptoms such as stuffy or runny nose, itchy or watery eyes, coughing, skin rash, etc.¹

Due to the significant link between mould allergy and respiratory symptoms, preventing mould is crucial for improving overall health. Research suggests that people diagnosed with respiratory conditions, such as asthma, may experience worsened symptoms and more frequent attacks due to mould. Therefore, preventing mould growth can minimise the risk of further respiratory complications. As mould grows in humid environments, the goal is to ventilate areas frequently to regulate humidity and repair any damaged pipes or water systems that could cause dampness, thereby preventing mould growth.^1,2,3

Understanding Mould Allergies

As mould allergies typically present with respiratory symptoms similar to hayfever, it can trigger an otherwise well-controlled asthma condition to flare up as the spores are inhaled into the lungs. Common symptoms of mould allergy include:^1,3

• Red and/or watery eyes
• Swollen eyes
• Itchy eyes, nose, ears or mouth
• Stuffy or runny nose
• Mucus running down the throat from behind the nose, or a sore throat
• Shortness of breath 

Various types of mould can be found in homes, and the types that cause allergy symptoms are Alternaria, Aspergillus, Cladosporium and Penicillium. These can be found indoors and outdoors. Alternaria and Aspergillus are typically found outdoors in plants and soil; however, these can be brought into the home. On the other hand, Cladosporium is found in carpets and wallpaper, whereas Penicillium is found in decaying matter like food.^3,5

Some people experience no symptoms when they come in contact with Aspergillus, however, others with weakened immune systems and chronic lung conditions such as asthma may be at risk of developing infections. Children are more vulnerable to reactions from mould allergies as their airways are smaller and narrower than those of adults. Likewise, factors such as pre-existing conditions, such as heart diseases, make elderly people more susceptible to developing further health issues from mould exposure.^1,2,4,7

Identify Mould-Prone Areas in the Home

Common areas where mould can grow include:^6,7

• The bathroom is a high-humidity environment due to constant use of water, creating damp surfaces for mould growth under the sink, on the shower curtains and on tile grout
• In kitchens, sinks and other appliances used to prepare meals or store food items could lead to moisture build-up and mould growth if not properly ventilated
• Basements and crawl spaces tend to be more prone to mould build-up as they typically lack good ventilation
• Attics are also prone to dampness and condensation due to poor ventilation, which is a prime environment for mould growth
• HVAC systems manage the temperature and air quality in a building, these systems are also prone to moisture and dust buildup leading to mould growth
• Windows and doors can accumulate condensation when there are leaks, which can cause mould growth

Prevention Strategies by Area

To prevent allergies from mould, aim to maintain indoor humidity between 30-50% and use mould-resistant materials in renovations. Regular inspections for signs of water damage or moisture build-up can help identify areas that require immediate attention to prevent mould growth. Ensuring indoor plants are kept to a minimum and using mould-resistant soil will also reduce the likelihood of certain types of mould found in plants which are known to cause allergies. Also, avoid wall-to-wall carpeting in moisture-prone areas such as bathrooms and kitchens, because this increases the risk of mould growing due to moisture and potential leaks or spills being trapped in the carpet fibres.⁷

Bathrooms

To ensure proper ventilation, it is advisable to use exhaust fans and to dry off wet surfaces such as tiles, showers and bathtubs. Mould resistant paint can be used as well on bathroom walls as an extra preventative measure.

Kitchens

Use exhaust fans when cooking, keep food covered and fix any leaks immediately to prevent moisture buildup. Clean all spills and ensure to keep trash covered to prevent the spread of mould spores from decaying food. 

Basements and Crawl Spaces

As these spaces can have stagnant air due to poor ventilation, adequate insulation materials should be used and vapour barriers installed to rectify these issues. Fixing any foundation leaks, maintaining gutters and using high-quality dehumidifiers would also be effective in preventing mould in these areas.

Attics

These areas are sometimes used as extra storage space; however, storing items that easily absorb moisture would encourage mould growth, especially if they come in contact with any leaks from the roof. Therefore, it is important to maintain proper airflow and insulation, regularly check and fix any roof leaks and avoid storing these moisture-prone items in attics.

HVAC Systems

These systems are essential for maintaining good air quality in the home; therefore, it is crucial to ensure they are functioning properly by cleaning all air ducts and vents frequently and replacing filters regularly. Using HEPA filters in the HVAC system is even more beneficial for those with allergies or respiratory conditions as they have proven to be effective at trapping a high percentage of air pollutants, including mould spores indoors.

Windows and Doors

Regularly cleaning window sills and frames will eliminate any build-up of moisture and dust that could have encouraged mould growth. To further prevent this issue, opt for double-glazed windows as these reduce condensation, which is usually a key contributor to mould growth.

Summary

To allergy-proof your home against mould, the primary focus would be to improve ventilation and control humidity. This can be achieved effectively by using dehumidifiers and exhaust fans, especially in moisture-prone areas like the bathroom and kitchen. It is recommended to fix leaks to prevent moisture build-up and to clean spills regularly. In addition, using and replacing HEPA filters indoors will help trap any mould spores from spreading and improve the air quality, which would minimise allergic reactions and maintain the overall integrity of the home and your health.

FAQs

How do I know if mould is the cause of my allergies?

Your symptoms will be similar to those of hayfever, which include sneezing, congestion, itchy and/or red eyes, skin irritation and coughing, if worsened after cleaning or in damp areas.

Where is mould likely to grow in my home?

In moist areas that could be poorly ventilated such as the bathroom, kitchen, under the sink, basement, attic, around windows and doors. 

Can air purifiers help with mould allergies?

Yes, air purifiers with HEPA filters trap mould spores that have been released into the air, reducing your exposure to them; however, they cannot remove mould growth that already exists. Aim to change the filters regularly for optimum functionality.

What is the ideal humidity level to prevent mould growth indoors?

50% is ideal; however, a minimum of 30% is required, which can be monitored using a hygrometer. A dehumidifier or humidifier can help achieve the appropriate level.

Which cleaning products are safe and effective for mould?

The safest ingredients for cleaning around the house to remove or prevent mould are vinegar, baking soda, and hydrogen peroxide; however, it is advisable to wear protective gear and ensure proper ventilation.

How often should I clean or inspect for mould?

Clean regularly as much as possible, address any leaks or condensation immediately to prevent mouldfrom developing and inspect areas in the home every month. 

When should I call a professional for mould issues?

If the mould covers a large surface or the area smells musty but the mould is not visible, it could be hidden. If you have extensive water damage, your DIY methods have not been successful, you have significant health concerns or plan to sell/rent the property, it would be safer to get a professional’s input.