Air pollution is when unwanted chemicals and poisonous substances are added to air, making it harmful to most organisms such as humans, plants, animals, etc... and even the atmosphere.
By different human activities, we add a lot
of smoke and dust into the air.
The biggest cause of air pollution is the use of fossil fuels.
These are mainly coal, petrol/diesel, and natural gas.
For example, if you have been in the car before and are stuck in traffic,
you will see fumes coming out of many vehicles.
These fumes are poisonous gasses that make the air polluted.