PRELIMINARY-RESULTS OF AMBIENT MEASUREMENTS WITH A MULTISTAGE IMPACTOR

Ambient air measurements were conducted with an eight-stage Sierra imp actor in Dusseldorf and Duisburg, Germany. In addition to gravimetric routine measurements in both cities with the aid of a High Volume Samp ler PM10, dust particles were collected on nucleopore filters and anal yzed for chemical compounds on the eight impactor stages with a scanni ng electron microscope equipped with an energy dispersive x-ray spectr ometer and an image analysis unit. Polydisperse glass beads and glass fibers were used in calibrating the multistage cascade impactor. Colle ction efficiency curves are presented together with computed values fo r the glass dusts. Comparative measurements in Dusseldorf and Duisburg revealed differences from city to city due to their respective indust rial character. The filter loading on impactor stages 1 and 2 was too low to be evaluated. Furthermore, the excessive deposition of droplets on the last stage prevented evaluation. Due to the industrial charact er of Duisburg, the gravimetric dust concentration was about 80 mug/m3 air and thus twice that of Dusseldorf. The concentration of metals (F e, Zn, Mn, Pb) was higher in Duisburg; organic compounds were excessiv e in Dusseldorf.