Mould is a type of microorganism that produce spores (the equivalent of seeds in plants) and these are very abundant both inside and outside. They can act as a potent allergen in some people and may lead to serious lung disease, known as aspergillosis. Damp patches in the home, or homes that have not been lived in for some time, allow moulds to flourish and you can end up with a mould infested home. Moreover, although black patches of mould are familiar to everyone, some mould species are invisible, so you do not know they are present, shedding spores into the surrounding air. Most mould spores are between 2 and 10 microns in size and therefore remain airborne for a long time, ready to be inhaled into the lungs where they may produce an allergic reaction.
There are many home settings where you may be exposed to mould spores. These are mainly where damp may be an issue and include:
• Any building that has been flooded.
• Rooms that are not normally heated and are cold compared with the rest of the house. Condensation and dampness will encourage mould growth here.
• Bathrooms are obvious sources of mould growth because of potential condensation and dampness.
• Buildings that have been diagnosed with either wet or dry rot, which is all too common in older houses.
• Buildings where the air is damp because they are near a river, the sea or a lake.
• Buildings that are being renovated, where old timbers are being removed. This process could release a large number of mould spores.
• Buildings which have a lot of indoor plants (maybe in a conservatory). Moulds love to grow on the surface of the soil around a growing plant.
• Cellars and basements, which are naturally more damp than upper rooms.
• Any building that has been unoccupied for a length of time is a mould risk because there could have been leakage from the roof, from the gutters or foundations. These could go undetected for months, spreading damp into the building.
Bear in mind that there will be more mould around in the winter because damp is more likely when it is cold. Also, you can be exposed to mould if you are clearing out clothes, books or furnishings that have been around for a long time. They have had years to accumulate mould spores. Even food kept past its sell-by date may be a source of mould – especially cheese and vegetables kept in plastic bags.
Tackling household mould
First, you need to know what you are looking for and where you might find it. Moulds come in all kinds of colours. The black of the Aspergillus niger mould appears in the door seals of the fridge, on the walls of bathrooms and around window frames. It is easy to mistake this for ordinary dirt. A pinkish-red mould may appear on the shower curtain or elsewhere in the bedroom. The green, grey, white or black moulds that grow on rotting foods are familiar to most people. But there are also invisible or hard-to-spot moulds that could be growing anywhere damp in the house.
The best approach to tackling your mould problem is to take steps to reduce condensation and dampness. Human activities in the home generate a huge amount of water vapour that needs to escape. With the modern trend towards insulation and energy efficiency, this can be difficult.
Here are some suggestions for creating a drier and improved air quality in your home:
• Check the structure of the house – dealing with any plumbing leaks, cracks in walls or leaks from the roof.
• Day-to-day, keep the kitchen door closed when cooking, and the bathroom door closed when showering or bathing. Keep lids on pans and turn off the kettle as soon as it has boiled.
• Try to dry clothes outside or in a tumble dryer, rather than laying damp clothes on radiators or hangers.
• Wipe down tiles after a shower so moisture does not cling to them.
• Ventilate the whole house, by opening all the windows, whenever you can.
• Don’t have carpet in bathrooms or basements, as these trap moisture.
• Fit double glazing and replace metal window frames with plastic to discourage condensation.
• If you have a shower curtain, replace this regularly.
• A vacuum cleaner fitted with a high-efficiency particulate air (HEPA) filter will trap mould particles in the air.
The reduction of dampness in your property can be an ongoing process. However, you might need to get rid of mould patches now to reduce allergy symptoms. This, in itself, will release lots of mould spores so the person with an allergy to mould should not do this themselves and, indeed, should keep out of the property when the work is being done.
Mould eradication work involves:
• Getting rid of anything that is obviously mouldy, like books, clothes and carpet
• Fridges, freezers, window frames, tiles and walls should be cleaned of mould very thoroughly.
• What to use in cleaning mould? White spirit, white vinegar and bleach can be used and specialists brought in to clear mould may use ozone. All may exacerbate allergic symptoms, so you might want to look at a specialist solution like Allermould spray.
• Fit a dehumidifier to rooms that are especially affected by damp.
The reason why it is important to tackle mould is that the Aspergillus family of mould can cause severe disease. Allergic bronchopulmonary aspergillosis (ABPA) is an allergy to Aspergillus spores, that affects around 2.5% of those with adult asthma and is also common in those with cystic fibrosis. In the long term, ABPA can lead to permanent lung damage. There is also a condition called fungal asthma, where people who have asthma are sensitised to Aspergillus without actually having ABPA.
There is also a disease called aspergilloma where the Aspergillus fungus actually grows in cavities in the lung that were created by previous lung disease. People with the lung disease bronchiectasis, with or without cystic fibrosis, are also susceptible to low-grade infection with Aspergillus
Aspergillus may also infect the sinuses, producing allergic sinusitis, the growth of a fungal ball, or invasive aspergillosis. All of these problems caused by Aspergillus are worse among those who have weakened immune systems. In this situation, the condition is called invasive aspergillosis and it can be life-threatening.
• Aspergillus website: www.aspergillus.org.uk
• World Health Organization guidelines on for Indoor Air Quality Dampness and Mould can be found at: http://www.euro.who.int/__data/assets/pdf_file/0017/43325/E92645.pdf