Estimations of Real-World N₂O Emissions from Road Vehicles by Means of Measurements in a Traffic Tunnel

Abstract

Ambient air measurements of N₂O, NO_x, CO, and HC based on grab sampling 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 balance—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.