Mould spores and yeasts in outdoor air

Most inviable spore counts of outdoor air in Europe are based on Burkard spore trap results. For viable counts different kinds of slit samplers and Andersen sampler are used. Results of viable and inviable sampling methods are not completely comparable, but the results complete each other. Spore frequencies in outdoor air are almost equal in different Nordic countries. Cladosporium is the most important spore type everywhere. In South Finland it accounts for ca. 85% of viable and ca. 50% inviable spore counts. The frequencies are lower in the country than in town. Cladosporium frequencies decrease northwards so that in Lapland the percentage is only ca. 5 and the maxima are 1/4-1/5 of those in South Finland. The frequencies of Alternaria spores are 4-5 times lower in Nordic countries than in Middle Europe. E.g. in Turku weekly maxima have been ca. 250 spores X m-3, in the country even lower. Penicillium accounts for ca. 4% of all colonies in viable counts in South Finland, Botrytis 2%, and yeasts also ca. 2%. The most important yeasts are Cryptococcus albidus, Cr. laurentii, Sporobolomyces roseus and Rhodotorula species. Actinomycetes very seldom occur on culture plates, only 0.02% of all.