External-beam PIGE for fluorine determination in atmospheric aerosol

Air pollution measurements have been performed at Montelupo, a town about 20 km west of Florence, characterised by the presence of a large number of ceramic and glass factories just inside the inhabited area. Both filters collecting aerosols during 24 h and streaker filters with I-h resolution capability have been analysed, using external Particle Induced X-ray Emission (PIXE) and Proton-Induced Gamma-Ray Emission (PIGE) simultaneously. The best operating conditions for getting quantitative information from the PIGE analysis of fluorine in the external beam set-up have been investigated. The minimum detection limit for the concentration of fluorine in air is in the order of 10 ng/m(3). Some specific results concerning fluorine determination in both the 24 and l-h resolution measurements are finally presented. While the average detected concentrations in air come out to be well below the air quality limits, lime episodes of relatively higher concentration have been detected and thanks to the time correlation with the other elements the origin of these pollution episodes can be hypothesised with a good degree of confidence. (C) 1998 Elsevier Science B.V.