Atmospheric carbon dioxide concentration variations in Rome: relationship with traffic level and urban park size

Carbon dioxide (CO2) concentration variations in Rome in the period January 2009 to December 2010 was monitored. Five representative sites (T sites) in the city centre with different traffic levels and urbanistic characteristics, and four urban parks (P sites) of different sizes were selected. The regression analysis underlines the significant (p a parts per thousand currency signaEuro parts per thousand 0.05) correlation between traffic levels and CO2 concentration. Considering the daytime CO2 concentration peak among T sites, Cerchi Street and Teatro Marcello Street, located in the city centre and closed by buildings, showed the highest traffic levels (85 +/- 3 and 63 +/- 2 cars min(-1), respectively) and the highest CO2 concentration (512 +/- 11 and 488 +/- 8 ppm, respectively). With regards to the considered P sites, those extending over the largest surface areas (Villa Pamphilj Park and Villa Borghese Park, 180 and 80 ha, respectively) characterized by large tree coverage (81 ha and 60 ha, respectively) had a significant lower CO2 concentration (404 +/- 9 ppm, mean value) than those extending over a small surface area (Villa Torlonia Park and Villa Celimontana Park, 14 ha and 11 ha, respectively). More efforts should be made to further reduce CO2 concentration in the cities in order to ameliorate ecosystem services related to urban parks.