Analysis of air particulate benzo[ a]pyrene by a specific enzyme immunoassay: correlation with chemical and atmospheric parameters

Abstract

A specific and sensitive enzyme immunoassay for benzo[ a]pyrene (BaP) analysis in air particulate matter has been developed and validated. The low detection limit (1 ng/tube) and the rapidity of the assay permitted extensive study (daily for eighteen months) of BaP concentration in air particulate matter in the city of Bologna. For each assay air was aspirated for 24 h and passed through a cellulose filter which retained the particulate matter and, after a simple extraction step, the BaP was quantitatively analyzed. Pb, Cr, V, Ni and Cd and total particles were also measured from the same filter. Meteorological parameters including temperature, humidity, rain, wind, barometric pressure and cloudiness were recorded. Exhaust gases such as NO 2, CO and SO 2 were also monitored daily. The data were analyzed by a chemometrical approach involving univariate, bivariate and multivariate analysis. The obtained results show a good predictive power of BaP with respect to the presence of metals and gases, and we were also able to identify two sources of BaP, i.e., heating and traffic. Weather conditions in general, and temperature and cloudiness in particular, play a major role in determining BaP levels. During spring and summer, BaP/Pb ratio was drastically reduced as a result of increased solar radiation and temperature, which may be a cause of BaP photodecomposition. The overall results suggest that BaP analysis of air particulate matter is useful in monitoring urban environmental pollution, and that this method could be complementary to conventional ones which identify markers such as gases or heavy metals, resulting in a more complete and detailed monitoring program of urban air pollution.