Aerobiologia 15: 39–47, 1999. © 1999 Kluwer Academic Publishers. Printed in the Netherlands. 39 Occurrence of airborne Cladosporium and Alternaria spores in Southern and Central Poland in 1995–1996 Danuta Ste ˛ palska*, Krystyna Harmata, Idalia Kasprzyk, Dorota Myszkowska & Alicja Stach Institute of Botany, Jagiellonian University, Lubicz 46, 31-512 Cracow, Poland (*author for correspondence, fax: +48 12 4230949) (Received 2 April 1998; accepted in final form 29 October 1998) Key words: aeroallergens, aerobiological monitoring, Alternaria, Cladosporium, Penicillium spores Abstract The concentration of airborne spores of Cladosporium and Alternaria has been investigated at five monitoring stations situated in cities from the foot of the Tatra Mountains to central Poland along a south-north transect (Zakopane, Kraków, Ostrowiec ´ Swie ˛tokrzyski, Warszawa, Pozna´ n) i.e. from a height of 900 m to 80 m above sea level. The aerobiological monitoring of fungal spores was performed by means of five Burkard volumetric spore traps. Cladosporium spores were dominant at all the stations. The highest Cladosporium and Alternaria spore concen- trations were observed at all the sites in July and August, except at Warszawa in both years and at Pozna´ n in 1995 where the maximum of Cladosporium spores occurred in June and July, and at Ostrowiec ´ Swie ˛tokrzyski in 1995 where the maximum was found in July, August and September. Fungal spore concentrations in Zakopane and Kraków were significantly lower than those in Ostrowiec ´ Swie ˛tokrzyski, Warszawa and Pozna´ n and periods of abundant Cladosporium spore occurrence were different in these two groups of monitoring stations. 1. Introduction The first investigations of airborne fungal spores in Poland were carried out in the cities of Kraków and Rabka in 1960 (Weiss, 1962). Fifteen types of fungal spores were identified then, including Cladosporium which had the highest concentration in the total spore count. Studies of the concentration of fungal spores performed to date in Poland refer to outdoor analyses (Gawet et al., 1996) as well as indoor analyses (Me ˛drela-Kuder, 1991). Many surveys of the occur- rence of Cladosporium spores in different regions of the world clearly show their dominance in comparison with other spores (Mitakakis et al., 1997; Shaheen, 1992). However, in the United States, various surveys have reported Alternaria more frequently than other moulds (except on the Pacific Coast where this taxon was found only sporadically or in reduced numbers (Prince and Meyer, 1976)). Even though mould spores are present in the air in concentrations considerably greater than those of pollen grains, the frequency of allergic respiratory diseases due to moulds is usually much lower than that due to pollen grains of vascular plants (D’Amato and Spieksma, 1995). The most important fungal allergen sources are found among the fungi from the class of the Deuteromycetes. For Alternaria and Cladosporium regarded as the main allergenic fungi, threshold concentrations for evoking allergic symptoms are esti- mated to be 100 spores m −3 air and 3000 spores m −3 air respectively (Gravesen, 1979). The main reason for different threshold values of Cladosporium and Alternaria spores is that volumes of these parti- cles are different: 10–20 Cladosporium spores may correspond to one Alternaria spore.