Allergy and fungal spores
Moulds, like mushrooms, are types of fungus. They grow on vegetation and animals, examples being alternaria, aspergillus and cladosporium. Their reproductive parts – called spores – are transported through the air like pollen, their aim being to find a hospitable environment in which to flourish and grow. However, when these spores – which are invisible to the naked eye – are inhaled by a person who is sensitive to them, hay fever can arise.
Unlike pollen, which has a particular season, moulds are present all the year round in many parts of the world. Their numbers are mainly governed by weather conditions such as rain, wind and temperature. For example, after a spring thaw outdoor moulds begin to flourish, sending ever greater numbers of spores into the air by the warmest days of summer. In climates that are consistently warm, moulds are in evidence throughout the whole year.
Humidity allows mould to propagate and produce spores, and is therefore its greatest ally. Spending time in a damp environment such as a garage or basement can bring on typical allergy symptoms – sneezing, a streaming nose, watering eyes and so on. It is recommended, therefore, that a susceptible person try to remain in places with low humidity (less than 40 per cent).
The amount of mould in the air is measured daily by a variety of methods and the number of grains per cubic metre of air is reported on some websites, along with the daily pollen count.
Outdoor mould is likely to grow in the following places:
• compost heaps with dead leaves and rotting vegetables
• outbuildings
• rotting wood piles
• hay and grain fields
• soil.
Indoor moulds – often referred to as mildew – can give rise to year-round symptoms in a susceptible person. The spores are too minuscule to be seen by the naked eye and particularly thrive in places where air does not circulate freely, such as attics and basements, where there are high levels of humidity, and in places where food is stored, prepared and disposed of. The following are possible areas that attract mould:
• potted plants
• leaky attics
• bathroom shower curtains and rubber non-slip mats
• damp towels and clothing
• pet litter
• around window frames
• rubbish bins
• old mattresses
• leaky pipes and taps
• foam rubber pillows
• refrigerator drip trays and rubber door gaskets
• other food storage areas
• pages of old books (the musty smell is a good indicator that a book is mouldy)
• damp areas of a poorly ventilated room
• damp cellars or basements
• poorly ventilated wardrobes
• over-stuffed furniture
• carpets
• old peeling wallpaper and paint.