As far as traffic is concerned, air pollution has been reduced through the introduction of unleaded gasoline, which meanwhile constitutes 95 percent of gasoline sales. Ever greater reductions in the concentrations of nitrogen oxide, hydrocarbons and carbon monoxide in the air have been achieved especially by the introduction of the closed-loop three-way catalytic converter, which limits emissions of these pollutants. Today all new automobiles with gasoline engines throughout the EU must meet emissions standards that can only be attained with such an exhaust treatment system. Unfortunately, however, the rapid increase in traffic - especially truck traffic - has partially offset the reductions achieved thus far through this new technology. Germany is also striving for the adoption of uni form and cleaner fuel formulas in the whole of the EU, for this would help reduce the emissions of the entire vehicle fleet. Carbon dioxide emissions from motor vehicles, noise caused by traffic, and fragmentation of the land through construction of transport networks all call for further planning and technical measures too in order to make environmentally sound mobility possible in Germany.

Keeping the air clean is an international challenge as well. A substantial amount of the pollution in Germany comes from neighboring countries, while half of the pollutants emitted in Germany are carried by the wind to other countries. Accords such as the 1979 Geneva Convention on Long-Range Transboundary Air Pollution and the protocols thereto for the reduction of emissions of sulphur dioxide, nitrogen oxides and volatile organic compounds are thus of great importance. In July 1995, the so-called “Summer Smog Act” entered into force. Pursuant to this act, the use of motor vehicles with high-emission gasoline and diesel engines is prohibited when at least three air quality measuring stations in the Federal Republic which are at least 50 kilometers and no more than 250 kilometers apart register a mean hourly ozone concentration of 240 micrograms per cubic meter of air and such ozone concentrations can also be expected in the vicinity of these measuring stations the following day. The ban on driving takes effect at 6:00 a.m. on the day following the announcement and lasts for 24 hours.