text: Limiting car usage would also be very helpful in cleaning up the environment. In "In German Suburb, Life Goes On Without Cars" the author states, "Passenger cars are responsible for 12 percent of greenhouse gas emissions in Europe...and up to 50 percent in car-intensive areas in the United States." Limiting the amount people can drive their cars could reduce a hefty amount of pollution in our air. In France, they limitied the amount of people who were allowed to drive for two days. Paris has more pollution in their air then most European cities, but putting regulations on who could drive significantly reduced the amount of smog in just a few days, according to Robert Duffer.