What is air pollution? is dirt in the air This is a big problem in some parts of the world, What causes pollution? People cause it by burning fuel buses, homes, schools, and trains. The smoke from burning fuel has poison gases and dust. These enter the air and make it dirty. Why is air pollution bad? The dirty air hurts people. It helps to cause more colds, coughs and diseases of the heart and lungs lt also hurts plants and animals and makes clothing and buildings dirty.