Improvements in urban air quality remain elusive in large citiesthroughout the world, including those in the united states where efforts have continued over 20 years to reduce emissions from vehiclesand other sources. Although technological advances in gasoline and diesel-fueled vehicles and in their emission control systems and fuel have resulted in impressive emissions reudctions, the combination of more vehicle-miles traveled and other factors offsets these improvements. Tightening further vehicle emissions standards in developedcountries would be costly and -- judging by the continuing presenceof ambient ozone in urban areas -- ineffective policy. Rather, efforts to target high-emissions vehicles and to impose fees on fuels, vehicles, or emissions may prove to be more cost-effective. For developing countries, the removal of lead from motor fuels and impositionof economic incentives to control transportation are potentially cost-effective strategies. This paper appears in transportation research record no. 1312, Energy and environmental issues 1991.
Abstract