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.Cladosporiumis 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.Cladosporiumfrequencies 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 ofAlternariaspores are 4–5 times lower in Nordic countries than in Middle Europe. E.g. in Turku weekly maxima have been ca. 250 spores×m−3, in the country even lower.Penicilliumaccounts for ca. 4% of all colonies in viable counts in South Finland,Botrytis2%, and yeasts also ca. 2%. The most important yeasts areCryptococcus albidus, Cr. laurentii, Sporobolomyces roseusandRhodotorulaspecies.Actinomycetesvery seldom occur on culture plates, only 0.02%