Air pollution can mean many different things. Wikipedia overcomplicates things and describes it as “the modification of the natural characteristics of the atmosphere by a chemical, particulate matter, or biological agent”, whilst others over-simplify it by saying it refers to “the pollution of the air”.
Pollution is usually described as the introduction of harmful substances, in this case, into the air. This could be sulphur, carbon, or nitrogen and is usually caused be us. Nature can also pollute the atmosphere, volcanoes for example, but the vast majority is created by ourselves.
There are many ways we can reduce the amount of air pollution we cause, such as buying energy from renewable sources, or limiting the amount of driving and air travel that we do. If you haven’t read it already, there are some more ideas in our free eBook – 100 Ways To Save The Planet. More suggestions welcome of course.