In developed countries, people usually have more than one cars and it is one of the reasons why air pollution is becoming worsen. People drive their own car too often, so the temperature is increasing each year. However, some people still do not care about it until the price of gasoline goes up. They find out that taking the bus or train is cheaper for them and helpful for the earth. The benefits of using public transportation make people comfortable, and it is also affordable, but the most important point is that the more people use them, the less air pollution we produce.