text: With a smaller amount of people using their personal vehicles, less gas emissions are becoming a part of the Earth's atmosphere. Humans breathe in the gases that are polluting the air and can become sick from it. The environment suffers from the dirty air and may not be able to sustain life if there is not a stop to the large amounts of pollutants being emitted into the air. In the United States, passenger cars are the cause of "up to 50 percent" of greenhouse gas emissions while in Europe they are "responsible for 12 percent" (Rosenthal). This means that the car use in the United States is ruining the air around us and assists greatly in creating a disgusting environment. In popular and global cities, pollution is even more noticeable and overwhelming. For example, in Paris smog has become an everlasting issue. The climate in the area contributes to the smog filling the air along with the use of cars: "Cold nights and warm days caused the warmer layer of air to trap car emissions" (Chicago Tribune). To reduce the smog in the area, an elaborate plan was taken into action. Cars with even license plates could not drive on certain days and cars with odd license plates could not drive on the other days. By doing this, the air in Paris cleared up dramtically. Therefore by promoting a system where car usage is not as common, the environment can become healthier and cleaner, which benefits the citizens of the Earth.