Fluorescence microscopic investigation of airborne particles and micro-organisms in an exhibition hall during an international trade fair

Measurements were conducted at the trade fair Biotechnica 2011 in Hannover, Germany. The concentrations of different particle size fractions in the air of the exhibition hall were measured by Bio-aerosol-Spectrometer and the numbers of airborne bacteria and mould spores were determined by cultivation and by a fluorescence microscopic method. Bacteria-containing particles were also classified with the latter method. The concentrations of bacteria (on average 30,500 cells/m(3) and 410 cfu/m(3)) and moulds (on average 1,090 cells/m(3) and 31 cfu/m(3)) were slightly higher than in ambient air. Their concentrations showed large variations during the trade show as well as those of different particle size fractions. Both were influenced heavily by the subjectively observed numbers of visitors and the general activity in the course of the day. Of the bacteria detected with the fluorescence microscopic method, 45% were most likely of human origin and found on skin scales and in small droplets. Of the cultivated bacteria 70% belonged to the Gram positive cocci. The fluorescence microscopic method is suitable for the rapid detection and classification of selected airborne particles in the field.