text: Cars are defined as metal cases with lether seats powered by gas or diseal. Gas and disel are fuels that are harmful to the Earth and can cause harmful emission and greenhouse gases. These gasses can cause smog, or smoke and fog mixed together creating a grey cloud of unbreathable dense air. Smog is very harmful for the environment and can heat the Earth which is not the ideal for the human body. In France, smog, caused by car emissions became unbearable, thus causing the entire city of Paris to ban cars for five days. According to Robert Duffer, "Congestion was down 60 percent in the capital of France, after five days of intensifying smog" (Paris Bans Driving due to Smog Paragraph 14). Therefore cars and its horrible blow can cause a blanket of harmful reactant. Cars can also cause greenhouse gases which is when the heat of the day and the cool of the night trap in the harmful emissions of a car. These greenhouse gases can also heat the Earth and can harm humans. Elisabeth Rosenthal states, "Passenger cars are responible for 12 percent of greenhouse gas emissions in Euorpe...and up to 50 percent in some car-intensive areas in the United States" (Car-Free Cities Paragraph 5). In effort to save the Earth and the human race many cities and communties have adotped car-banning, reducing the amount of population caused buy cars.