A quantitative study of air-borne fungus spores in Dunedin, New Zealand.

By means of culture plates exposed in a Manning slit sampler, a quantitative survey of air-borne moulds has been made between March 1953 and April 1954 in and just outside a building in the city area of Dunedin, New Zealand. There was little difference between the yields from indoor and outdoor air. The average count throughout the year was 13·9 colonies per cubic foot. Lowest yields were obtained during the winter months (an average of 5·9 colonies per cu.ft.) and highest during the summer (25·1 colonies per cu.ft.). Cladosporium occurred most frequently (42·9 %), and Penicillium was the next most commonly encountered mould (34·2 %). Air-borne yeasts in the Dunedin city area were also surveyed between February 1953 and April 1954 by means of culture plates exposed in a slit sampler. The average density of viable yeasts was found to be one to two cells or clumps of cells to 2 cu.ft. of air. Almost all the isolates belonged to four major groups, Debaryomyces species (including imperfect forms of this genus), nonpathogenic Cryptococcus species, the Sporobolomyces-Rhodotorula group, and the yeast-like phase of Cladosporium . Debaryomyces kloeckeri and Cryptococcus diffluens were the species most commonly isolated. Experiments have suggested that air-borne yeasts may be selected by their ability to withstand the effects of drying and ultra-violet radiation.