Changed paragraph by teachers

The large population of Seoul has lead to several negative effects. At first, there is traffic jam. In every morning, we take many hours to commute. During rush hour, the public transportation system is crowded. Then this matter causes the air pollution. It’s difficult to breath in and out because of dirty air. There are many patients who have bronchial trouble. Finally the air polluted makes acid rain. When we are exposed to acid rain, it is bad effect to our hair. The acid rain also makes pollution to the underground water. We need to think how to overcome these problems.