S-29C2-2 Background/Aims: The impact on air pollution of the traffic restriction scheme in Milan “Ecopass” is questionable. Ecopass, allowing only low-emission cars enter the city center without paying a charge, was implemented in 2008 with expectations of a 30% decrease in particulate matter (PM10) levels. However, a field study conducted in 2009 showed no PM reductions in the city center, in spite of an objective decrease in vehicular traffic. Aerosolized black carbon (BC, also called elemental carbon) is a primary product of incomplete combustion and could be a better indicator of local air quality improvement than PM10, which is more representative of background pollution. The aim is to study BC in assessing Ecopass impact on air quality compared to PM. Methods: We measured BC and PM levels on the sidewalks of a radial metropolitan road characterized by 3 different traffic schemes: an outer segment without traffic restrictions, an intermediate one subject to Ecopass, and an inner pedestrian zone. BC was measured with a handheld analyzer (microAeth Aethalometer AE51, Magee Scientific, Berkeley, CA), while PM was measured with a laser-operated particle analyzer (Aerocet 531, Met One, Grants Pass, OR). Results: PM levels were quite stable, with a mean ± standard deviation of 20.6 ± 3.2, 19.6 ± 2.2, and 21.2 ± 2.4 μg/m3 for PM1; of 26.5 ± 4.6, 24.2 ± 2.7, and 25.4 ± 2.7 μg/m3 for PM2.5; and of 69.0 ± 18.8, 54.5 ± 6.9, and 52.0 ± 7.1 μg/m3 for PM10, respectively for no-restriction, Ecopass, and pedestrian zone (significant only no-restriction/pedestrian zone for PM10). On the contrary, for BC levels a progressive reduction was found moving toward the least polluted area, with 12.2 ± 4.6, 6.9 ± 1.5, and 3.0 ± 0.6 μg/m3 for no-restriction, Ecopass, and pedestrian zone, respectively (P < 0.0001 for each comparison). BC/PM2.5 ratios were also distinctive for each area, being 46.2 ± 5.2, 28.4 ± 2.1, and 11.7 ± 1.2, respectively (P < 0.001). Conclusion: BC is more suitable than PM in detecting the impact of traffic restrictions on air quality.