Serious environserious environmental pollutionmental pollution

Air pollution is by far the most harmful form of pollution in our environment. ... deodorants and insect repellents cause severe damage to the Earth's environment.

Answeroil-shale;

It is useful for historians to write narratives so that history can be passed on from their point of view.  think about a story being told in third person, then think about it again being told in first person, by someone who actually experienced the event.