Personal exposure to allergenic pollen and mould spores in inland New South Wales, Australia

Background In inland NSW, Australia, allergic sensitization to the fungi Al ternaria and Cladosporium and to pollen is common and an important risk fac tor for asthma. Objective We report the results of a series of experiments designed to asse ss the nature of personal exposure to these airborne allergenic particles. We have tested the effect of exposure conditions and level of activity on m easurements of the personal exposure. Method Personal Ar Samplers (PAS) and Nasal Air Samplers (NAS) were employe d. NAS are fitted just inside the nose and collect inhaled particles by imp action, while the PAS use a pump-operated filter with constant air flow (2 L/min). Thirty-three subjects (adults and children) used both NAS and PAS s imultaneously for four one hour periods during which they performed activit ies or rested, both inside and outside their homes. Samples were analysed b y light microscopy. Alternaria spores, Cladosporium spores, grass pollen an d nongrass pollen were counted. Results Both samplers detected substantial variation in exposure between su bjects. Between members of the same household, the intrahouse correlation c oefficient ranged from <0 - 0.38. Levels of pollen grains and fungal spores inhaled were higher during periods of activity than during rest, and highe r while subjects were outdoors than indoors. During the active outdoor peri od, the number of Alternaria spores inhaled ranged from 4 to 794 (median 11 ) spores/hr, Cladosporium from 0 to 396 (median 4) spores/hr, grass pollen from 0 to 81 (median 1) grains/hr and nongrass pollen from 0 to 72 (median 5) grains/hr. Conclusion This is the first study to quantify individual inhaled levels of allergenic fungal spores and pollen under normal domestic circumstances. E xposure can be substantial and highly variable between individuals. The amo unt of particles inhaled relates both to location of the individual and act ivity being performed, independent of age group.