A 3-year study of relationships among atmospheric concentrations of polycyclic aromatic hydrocarbons, carbon monoxide and nitrogen oxides at an urban site

Particle-bound carcinogenic PAHs (benzo[ a]pyrene, benzofluoranthene isomers, indeno[1,2,3-cd]pyrene), benzo[e]pyrene (selected as a stable reference PAH), CO and nitrogen oxides (NO, NO, and NO,) were simultaneously measured at a street site in Rome. The aim was to investigate the possibility of using a conventional air quality parameter as a surrogate for carcinogenic PAHs at urban sites. Eighty-seven sample sets, corresponding to 344 sampling days, were statistically treated by standard univariate and bivariate methods. NO and NO, were the parameters most strongly correlated with PAHs (overall mean r = 0.92, for both), with the highest linearity and lowest scattering of data in the regression lines, but CO also showed a very good correlation (r = 0.86). Temporal variations of all these substances were substantially superimposable throughout the study. Summer results indicate, however, that PAH degradation may affect correlation under conditions of relatively high temperature and sunlight intensity. This preliminary investigation suggests that, at street level where pollution is traffic dominated, NO could be the most valid surrogate to roughly estimate PAH concentrations and trends, or PAH pollution ranking within a monitoring network. (C) 1999 Elsevier Science B.V. All rights reserved.