Correlations between PAHs and CO, NO, NO2, O-3 along an urban street

Since 1997 to 1999, bimonthly measures of daily PAH concentrations, adsorbe d on airborne particulate (PM10) have been carried out in Genoa (Italy), al ong a canyon street, crossed daily by about 27,000 vehicles. Simultaneous c oncentrations of CO, NO, NO2 were evaluated in the same sampling site. Ozon e concentrations were measured in two sampling stations, far from traffic, and their daily mean was used as a measure of oxidative strength of urban a ir in Genoa. PAHs correlate positively with CO and NO. Negative correlation s were found with NO2 and particularly with O-3 Cyclopenta(cd)pyrene was co nfirmed the most reactive PAH, while benzo(e)pyrene showed a relative stabi lity. Multiple linear regression analyses confirmed that PAH concentration covariates mainly with CO and O-3, while NO2 has negligible correlation. Ac cording to these results, benzo(a)pyrene concentrations are well predicted (standard error = 0.35 ng/m3), by the following equation: [BaP] = 1.4 + 0.31 [CO] - 0.015 [O-3] R-2 = 0.75 d.f. = 55 These results suggest that traffic is the main PAH source in the studied si te and in urban atmosphere PAHs adsorbed on suspended particulate may be de graded also by oxidation.