Pollution refers to the action of the introduction of pollutants into the environment, such as chemical substances or objects such as plastic.
Pollution tends to be very harmful to the environment and its fauna, by damaging the existing ecosystem and in some cases, making it completely uninhabitable.
Pollution is commonly produced by humans, the main contributors being nuclear plants.
In places like Beijing, in China, the pollution is so great that the air is almost impossible to breathe, so many people end up dying. Pollution is currently a worldwide problem, affecting different countries and cities in the world.