What is air pollution?

When our air gets dirty, we say it is polluted. This is called air pollution. Air pollution happens for many different reasons. In nature, air pollution gets created when volcanoes erupt, forest fires burn, and when plant pollen and dust are blown by the wind. The main causes of air pollution however, come from human activities that create pollution everyday, all over the world. In some areas that have a lot of air pollution, people develop an illness called asthma (pronounced AZ-muh) that makes it very difficult for them to breathe. Imagine trying to breathe in air through a straw. That's what asthma can feel like.