Ultrafine aerosols in workplaces - Conventions and practical examples

Ultrafine aerosols are aerosols with particles smaller than 100 nm. Such ae rosols have been regarded as a tentative cause of specific health effects, if the particles are insoluble or only slightly soluble. Ultrafine particle s are formed especially as condensates from thermic and chemical processes. Examples are welding fumes, metal fumes, carbon black, silica fumes or par ticulate diesel motor emissions. The institute for occupational safety - BI A in co-operation with the German Berufsgenossenschaften (institutions for statutory accident insurance and prevention) has started a campaign to meas ure ultrafine aerosols in selected industrial workplaces. For that purpose the number concentrations as well as the particle size distributions in the size range from approx. 10 nm to 500 nm are measured by using a scanning m obility particle sizer (SMPS, manufactured by TSI). The present state of th ese activities is presented and interesting findings are reported. Special attention is paid to specific conditions to be considered for measuring ult rafine aerosols in workplaces. Furthermore the efficiency of different resp iratory particle filters against ultrafine particles is dealt with.