Bioaerosols are considered to play a relevant role in atmospheric processes, but their sources, properties and spatiotemporal distribution in the atmosphere are not yet well characterized. In the Amazon Basin, primary biological aerosol particles (PBAP) account for a large fraction of coarse particulate matter, and fungal spores are among the most abundant PBAP there as well as in other vegetated continental regions. Furthermore, PBAP could also be important ice nuclei in Amazonia. Measurement data on the release of fungal spores under natural conditions, however, are sparse. Here we present 5 an experimental approach to analyze and quantify the spore release from fungi and other spore producing organisms under natural and laboratory conditions. For measurements under natural conditions, the samples were kept in their natural environment and a setup was developed to estimate the spore release numbers and sizes together with the microclimatic factors temperature and air humidity, as well as the mesoclimatic parameters net radiation, rain, and fog occurrence. For experiments in the laboratory, we developed a cuvette to assess the particle size and number of newly released fungal spores under 10 controlled conditions, simultaneously measuring temperature and relative humidity inside the cuvette. Both approaches were combined with bioaerosol sampling techniques to characterize the released particles by microscopic methods. For fruiting bodies of the basidiomycetous species, Rigidoporus microporus, the model species for which these techniques were tested, the highest frequency of spore release occurred in the range of 62 and 96 % relative humidity. The results obtained for this model species reveal characteristic spore release patterns linked to environmental or experimental conditions, indicating that the 15 moisture status of the sample may be a regulating factor, while temperature and light seem to play a minor role for this species.The presented approach enables systematic studies aimed at the quantification and validation of spore emission rates and inventories, which can be applied to a regional mapping of cryptogamic organisms under given environmental conditions. 1 of bioaerosol emissions, which is roughly 23 % of total primary organic aerosol emission (Fröhlich-Nowoisky et al., 2016; Graham et al., 2003; Heald and Spracklen, 2009; Jacobson and Streets, 2009;Sesartic et al., 2013).Species of Polyporales (Basidiomycota), the order of the model species of the present study, mostly colonize dead wood, 30where they form vegetative hyphae degrading the wood. On the surface of dead wood they form fruiting bodies with pores located at their lower side. The surface of these pores is covered by a hymenium, where basidiospores are produced on basidia.Each basidium externally forms mostly four asymmetrical basidiospores on little curved, tapering stalks, called sterigmata.The spores are fixed to the sterigmata at the hilum, which thus forms a characteristic feature of basidiospores.