Measurements of the Non Filterable Share of Heavy Metals and Metalloids in Ambient Air

Summary

Based on hints in the literature that some heavy metals like Cd and As may not be completely deposited on filters during ambient air measurements of suspended particulate matter (S.P.M.) we tested and developed a method for the complete collection of air borne metallic or metalloid compounds. Briefly the method consists in a series of cooled impingers filled with HNO₃, which are integrated by glass pipes into a conventional apparatus for the measurement of S.P.M. The results of two series of measurements in ambient air are presented. It can be shown that arsenic (15 – 28 %), lead (15 – 17 %) and copper (42 – 55 %) compounds have significant shares which are non filterable, whereas cadmium (72 – 73 %), nickel and chromium compounds even predominantly pass through the filters. The experiments, however, revealed also some analytical shortcomings of our method, which are discussed. Further work is in progress to improve the method and to validate further the preliminary results.