Mould spores are prolific everywhere. They include the black mould that forms on window frames and others that are found on decaying food; also mushrooms and fungi that grow wild. Exposure to mould is widespread, so it is difficult to determine how much mould an individual is exposed to in everyday life. Like dust allergens, mould allergies are perennial and allergic people exhibit symptoms throughout the year, although levels rise in the autumn, during wet, mild weather and harvesting.
Moulds release spores and it is these spores that cause the allergic reactions in people. Spores are microscopic particles released by moulds in their thousands into the atmosphere. Spores contact skin and nasal and bronchial membranes, causing symptoms such as rhinitis, itchy eyes, eczema and most importantly asthma. Several well-known conditions, such as Farmer's lung and Sauna-taker's lung, are caused by mould allergy.
Moulds favour damp, musty conditions; therefore piles of rotting leaves, grass cuttings, compost heaps, and garden sheds are prime environments for mould growth. Indoor moulds can be found on food that is going off, such as the black and white fur that is found on cheese, bread, fruit and vegetables.
The refrigerator is a key mould environment if not adequately cleaned and dried, particularly around the seal. Other types of mould can be found on window frames, especially when there is a lot of condensation on the windows, under wallpaper and on the soil of houseplants. Likewise, the damp environment caused by tumble dryers and baths and showers make the kitchen and bathroom danger zones.
The moulds which are most commonly associated with everyday modern living are found most of the year and in similar places. The most common moulds are as follows:
- Penicillium Notatum - is widely distributed in soils and can also be isolated from decaying vegetables and leaves. It is found on stored cereals and hay. In-house, this mould is the green-blue mould found on stale bread, fruits and nuts and it is the mould that is used in the production of blue/green mouldy cheese. This mould is present all year round, however its concentrations reach a peak during winter and spring. This mould is associated with indoor allergy.
- Cladosporium Herbarum - is the most frequently encountered mould in the air. Indoor concentrations of the spores reflect the outdoor concentration as this mould is easily transported through the air. Levels of this mould rise in the spring and peak in late summer and autumn. Cladosporium is one of the most common colonisers of dead plants and soil. This is the mould that is frequently found on uncleaned refrigerators, foodstuffs, window frames, straw, houses with poor ventilation and in low damp areas. This mould has also been isolated from fuel tanks, face creams, paints and textiles. It is the primary source of mould allergy.
- Aspergillus Fumigatus - is found in soils, leaf and plant litter, decaying vegetables and roots, bird droppings, tobacco and stored sweet potatoes. Compared to other moulds, the concentration of spores in the air is relatively low. This mould is associated with asthma, also with bronchitis and conditions such as Farmer's lung.
- Alternaria Alternata - found in soils, foodstuffs and textiles. The most common habitats for this mould are rotten wood, composts, bird's nests and forest plants. Black spots on tomatoes and other foods are attributed to this mould. This is generally considered to be an outside mould and appears when conditions are warm.
- Trichophyton Rubrum and Pityrosporum Orbicculare - are yeasts that live within the skin in certain types of eczema.
Moulds are prevalent throughout our environment. Most people associate mould with damp walls and similar extreme situations. The fact of the matter is that we are all exposed to moulds to varying extents in our everyday activities. The following measures will help minimise contact with moulds.
Avoiding indoor moulds
- Moulds flourish in damp environments, therefore one of the best ways to prevent their growth is VENTILATION.
- Avoid damp basements, compost piles, fallen leaves, cut grass, barns and wooded areas - or wear a face mask if these places or things are unavoidable.
- Thorough cleaning of the kitchen, bathroom and utility room with subsequent ventilation of these areas will help prevent mould growth. Pay particular attention to walls behind kitchen units and cupboards; the lack of ventilation often means that excess mould grows in these areas.
- Open windows and close internal kitchen and bathroom doors when cooking, showering or bathing to prevent steam entering other rooms. Keep bathroom surfaces dry. Do not hang wet clothes inside or over radiators.
- Do not let food decay. Clean and thoroughly dry problem areas such as refrigerator seals.
- Clean mould from window frames and dry condensation.
- Do not hang clothes in damp cupboards or pack clothes too tightly in wardrobes. Leave wardrobe doors ajar to ventilate the clothes
- Make sure that your tumble dryer is vented outside during use, or use a condenser-dryer. Try not to dry damp clothing indoors.
- When showering or cooking, keep internal doors closed to prevent damp air spreading through the house. Use extract fans and cooker hoods vented outside.
- Get rid of old foam pillows and mattresses.
- Do not bring in damp wood for the fire. Avoid burning wood inside that has been kept in a damp shed.
- Strip wallpaper from damp walls. Tackle any areas of dampness on walls etc.
- Remove piles of old newspapers.
- Keep houseplants to a minimum and change the soil regularly
- Do not use humidifiers.
- If using a dehumidifier, keep indoor humidity at 50% or less. Empty and clean the reservoir regularly
- Avoid using paraffin heaters and bottled gas heaters - they generate large amounts of moisture
Avoiding moulds outdoors
- Do not spend time in buildings where hay or grain is stored.
- Do not go into damp and musty buildings.
- Avoid cutting grass, raking leaves and turning compost heaps.
- Do not walk in the woods in mild damp conditions or among rotting leaves.
- Avoid country areas when harvesting, particularly when sunny and windy.
- Allergy bedding covers protect you from mould spores within the mattress, pillows and duvets.
- Filter facemasks, like those worn by cyclists, trap spores
- Mechanical ventilation systems can remove spores.
Solutions are available which eradicate moulds and deter their growth on windows, bathrooms and refrigerators and their frequent use is recommended.
For severe mould infestation, contact the environmental health department of your local authority for advice and assistance.
Last updated: March 2012