Calculated emission and measured immission of air pollution related to traffic flow on a motorway

Emissions of NOx from the traffic on a three-lane motorway have been calculated by means of an emission model purely based on traffic flow data. Hourly mean emissions for February 1990 are presented. For the same period, measurements of NO as well as meteorological measurements were taken at and close to the motorway. A long path instrument, based on the Differential Optical Absorption Spectroscopy (DOAS) principles was used for gas measurements in the ambient air. An atmospheric diffusion model was used in order to determine the traffic emissions that fully explained the concentration of the gas measured in the ambient air. Emission estimates based on these principles are presented as hourly values for an average day during February 1990. The emission estimates from the two mutually independent methods show striking similarities. It is concluded that a further developed model based on DOAS measurements, could be a flexible and cost effective method for the estimation of traffic emissions, for several gases and for complex traffic scenarios, implying new and better ways of comparing the environmental effects of different approaches to traffic planning solutions and infrastructural design.