Abstract

Spores of fungi and actinomycetes are almost always present in air but their numbers and types differ with time of day, weather, season and location (especially if this is dominated by large nearby spore sources). Without a source of spores in a building, numbers indoors are usually smaller than outdoors but the types found are similar. Heaviest exposure to airborne spores is often found in the workplace. Important sources are agricultural crops, especially during harvesting or during handling and processing after storage. mushrooms, wood for timber or pulping, composts, food processing and, increasingly, biotechnological processes. Many of the spores concerned are 1–5 µm in diameter and they may number up to 1010 spores m-3 air. Many of the organisms found are well-known allergens and have been implicated in occupational asthma or extrinsic allergic alveolitis. Some may also cause infection, e.g. Aspergillus fumigatus, or carry mycotoxins, e.g. Aspergillus flavus, while very intense exposure may cause ‘organic dust toxic syndrome’. Important factors in the development of occupational asthma and allergic alveolitis are predisposition and the nature, intensity and duration of exposure. Examples of exposure to fungal and actinomycete spores in different occupational environments are described.

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