This paper deals with two variables affecting the pollutant emission of automotive vehicles: the driver and the traffic control. These factors are shown to have a substantial influence on the pollutant emission of a given vehicle, whether or not that vehicle has an exhaust device.Based on actual data, a function which gives the emission of an average vehicle versus speed, acceleration, and time is defined.To study the influence of driver behavior, a simplified version of the problem which consists in controlling a vehicle through a sequence of lights is examined; it is found that pollutant emission may vary up to one order of magnitude, depending on the control policy, for given physical conditions. A driving policy which minimizes pollution can be found using dynamic programming.The second factor, traffic control, is represented by signal timing along an axis. It is shown that a stop-and-go flow of cars produces twice as much pollutant as an equivalent volume of smooth flow. The influence of the introduction of an ill-timed traffic light along a synchronized route is studied next. A possible method of evaluating pollution reduction with the implementation of a computer-control of traffic is thus obtained. Finally, the interaction between drivers and environment is considered. Possibilities of improving environmental factors and educating drivers to reduce the contribution of these two factors to pollution are discussed.