The environmental impact of vehicle emissions standards

Abstract

Vehicle emission standards are becoming an increasingly important instrument for the improvement of air quality in urban areas. With the introduction of Urban Clear Zones and Low Emission Zones it will be necessary not only to set targets for air quality but also emission standards for vehicles permitted to enter such zones. This paper reviews the EURO I and II standards in Europe and the California CARB measures and the future standards EURO III and IV and the US standards LEV, ULEV, MZEV and ZEV. The measured and predicted urban NOx emissions are compared over the period 1993-96. The concept of the Urban Clear Zone and the Low Emission Zone is discussed together with the likely impact on vehicle emission standards and on the design of vehicles required for access, and in particular, propulsion technologies.