Nitrous oxide (N2O) emissions from vehicles

Assessment of the impact of vehicle emissions on the global environment req uires accurate data concerning nitrous oxide, N2O, emissions. We report her ein "real-world" N2O emissions from road vehicles in a tunnel In Wuppertal, Germany, together with "laboratory" emission measurements conducted at the Ford Motor Company using a chassis dynamometer with a standard driving cyc le for 22 different cars and trucks. Consistent results were obtained from both approaches, suggesting that a good approximation of the average emissi on factor (g of N2O/g of CO2) = (6 + 2) x 10(-5). This corresponds to an em ission rate of 16-8 mg of N2O/km for vehicles with fuel economies of 12-6 L /1110 km (20-40 mi/U.S. gal). N2O emissions from vehicles have a global war ming impact, which is 1-3% of that of the CO2 emissions from vehicles. We e stimate that the global vehicle fleet emits 0.18 +/- 0.06 Tg of N2O yr(-1) (0.11 +/- 0.04 Tg of N yr(-1)), which represents 2-6% of the atmospheric gr owth rate of this species, In addition to N2O, laboratory vehicle emission measurements of NH3, HONO, and HCN are reported.