text: Paris has 67 percent of its vehicles run on diesel fuel, which is blamed for most of the air pollution. The rest of Western Europe has an average of 53.3 percent of vehcicles fueled by diesel. Car emissions are traped from the warm air caused by cold nights and warm days. A partial ban was created in Paris for driving to reducce the amount of pollution. Drivers with even number license plates could drive on certain days and odd number plates would drive on other days. After only five days the air pollution was down by 60 percent. In Bogota there are car free days and 118 miles of bicycle paths were constructed and the amount of traffic jams during rush hour were down by almost half.