Air pollution means dirtying the air. Air is really important for people. We can't live without it. But we don't realize that we're the ones making the air dirty. Clean air is necessary for life. There are many ways air gets dirty. Like when smoke goes into the air. People light fires to cook, make bricks, get rid of trash, and make roads. All these things make a lot of smoke and that smoke makes the air dirty. Another way is when trains, power plants, factories, buses, trucks, and cars use things like coal, oil, and petrol. All of these things also make smoke and make the air dirty. The worst air pollution happens in big industrial places with lots of factories. It also happens in big cities with many buses, trucks, and cars driving around every day. Sometimes, people in these places get really sick from breathing the dirty air and they can't get better. So, we need to do things to stop air pollution.