Evaluating the penetration of Cladosporium spores into the human respiratory system on the basis of aerobiological sampling results

The penetration of Cladosporium spores and spore aggregates into human airways was studied using three different spore sampling methods: 1) a Burkard spore trap for determining the aggregation degree of Cladosporium; two samplers, simulating the human respiratory system, 2) a 6-stage Andersen 2000 sampler, and 3) a new size-selective bioaerosol sampler (SSBAS), designed specifically for immunochemical and chemical analyses. The aggregation degree of Cladosporium spores varied between 1.0 and 1.3 spores per dispersal unit. Grouping seems to be of little if any importance to the penetration ability of Cladosporium spores into the respiratory tract. The distribution of spores in the Andersen and SSBAS differed significantly in the largest size class (spores greater than 7 microns in diameter); with the Andersen sampler only 10.8% of the spores were detected in stage 1, compared with 43% with the SSBAS. On the Andersen culture plates 95% of all colonies were detected in stages 1-4, where particles greater than 2.1 microns in diameter are trapped. In the SSBAS altogether 99.4% of spores were found in the first two filter stages (cutoff point approx. 2.5 microns in diameter). Conclusions regarding the penetration of spores to the lungs on the basis of aerobiological results should always be based on the use of properly calibrated spore traps.