text: More cities are starting to have car-free days to help with the pollution problems that are caused by automobile engines. Examples of these cities include Paris, France and Bogota, Colombia. Pollution is starting to be a big problem in big cities like these, so they have decided to take action. Pollution is destroying our atmosphere. The gases that are released from the exhaust of car engines slowly deteriorates the layer of atmosphere of our world. If cars begin to be frequently used like they are now, the atmosphere may become damaged beyond the condition for being fixed. Earth only has one atmosphere, so once it's gone, we can't get it back.