Watch out, it’s mould outside – Allergy UK


leavesWith a carpet of golden brown leaves settling all around us and a chill in the air, autumn is well and truly here. But how do the changing seasons affect the allergens in our outdoor environment? Outdoor mould, and even wet leaves can exacerbate allergic symptoms.

We know that as the winter months approach people tend to spend more time indoors with the central heating turned up, and doors and windows firmly shut to keep the heat in. This means our exposure to ‘indoor allergens’ increases to those such as house dust mite allergen (who thrive in warm, moist environments) pet allergen and mould). As a national charity we are often asked on our helpline at this time of year about how to prevent mould indoors. But mould can be a real problem for allergy sufferers outside, as well as in the confines of their home.

Outdoor mould levels are high in the autumn and mild winters or in persistently mild, wet weather. Fungal spores can be present for most of the year but thrive in mild damp air, so become plentiful in late summer, particularly after harvesting, then proliferate in the autumn. Mould counts are dictated by the weather and local conditions, which is why they can change in different seasons. Some spores are released in abundance at night and during rainy periods where there is high humidity, fog or dew.  They are especially prolific in woodland areas amongst trees and leaf piles. Most moulds live on dead vegetable matter which is why you find them in piles of autumn leaves, by dead branches or in compost heaps. Those susceptible to allergies should consider the presence of mould when out walking in woodlands in the autumn and winter months. Be aware of kicking up the leaves as you walk, these will produce millions of fungal spores which are released by movement or strong wind. Spores are extra microscopic, penetrating the smallest airways and sinuses not only triggering allergic reactions but they can also cause fungal infections, which are difficult to treat.

Mould spores can cause significant symptoms for those with atopic eczema, rhinitis and asthma. If you’re suffering persistent symptoms it could be due to a mould allergy. Symptoms of an allergy to mould include sneezing, runny nose, blocked nose, usually with congestion affecting the sinuses and a feeling of itching ears and throat. The eyes can also be itchy, red and swollen and this can be the most difficult to manage. Many people also have asthma exacerbations during early autumn, when their symptoms are triggered by high fungal spore counts as well as increased contact with viruses after the school autumn term begins.

If your rhinitis, asthma or eczema deteriorates in the autumn and winter, you are advised to undertake an accurate diagnosis of your allergens. Anybody with persistent or recurrent allergic-type symptoms should have a proper allergy assessment, ideally at an allergy centre as they are best placed to carry out a full clinical history. This is the most important step in any allergic diagnosis. Allergy UK can supply detail of your nearest allergist or appropriate specialist who will conduct appropriate tests.

Top tips:

  • Limit your outdoor activity when the mould count is high if you think you’re suffering with mould allergy
  • Avoid woodland walks in mild damp conditions with rotting leaves
  • Avoid kicking autumn leaves about
  • Consider wearing a mask when working in damp areas or raking leaves
  • If you have a compost heap, keep it covered to prevent the release of mould spores.

For further information see our factsheet on Pollens and Moulds in the Garden or if you need further advice please call our helpline on 01322 619898.

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