ESTIMATIONS OF REAL-WORLD N2O EMISSIONS FROM ROAD VEHICLES BY MEANS OF MEASUREMENTS IN A TRAFFIC TUNNEL

Ambient air measurements of N2O, NOx, CO, and HC based on grab samplin g were conducted in a major traffic tunnel in Sweden, that carries up to 4,000 vehicles per hour, in order to estimate real-world emissions of N2O for road traffic. Two different methods-relative and mass balan ce-were used to calculate a N2O emission factor for the mixed vehicle fleet, which gave an average emission factor, at average speeds of 30- 70 km/h, of approximately 25 mg N2O/km, with a range of 7-56 mg/km.