METHODS

SUMMARY: Spore trapping by the Petri dish method showed the incidence of air-borne Cladosporium herbarum spores, which fluctuated markedly from day to day, to be similar in Central London and in an outer suburb throughout the year. Although it was in Europe that the ability of air-borne fungus spores to act as allergens was first recognized, the most detailed surveys of the fungus spore content of the air have been made in the United States. Increasing attention is, however, being paid to this topic elsewhere, and in Britain the Asthma and Allergy Unit a t Cardiff is now supplementing studies on the incidence of air-borne pollen with investigations on the occurrence of fungus spores. Reports have already appeared on the incidence of AZternaria spores (Hyde & Williams, 1946) and of fungus spores in general (Hyde & Williams, 1949). ' In 1946, during a search for new antibiotics, it was decided to follow the clue provided by Fleming's discovery of penicillin and to sample the fungus spores present in the atmosphere, but by design, and this note summarizes certain data obtained by the systematic exposure of plates in and aroun