The first and most important effect of pollution is on human health. There are many
ways in which pollution affects human health and the first of these is smog. Smog occurs
in big cities and industrial areas, and is caused by car exhaust fumes and/or factory
emissions. People who live and work in areas with a lot of smog have to breathe it in,
and, over a longer period of time, this can cause lung diseases such as asthma. Another
example is the pollution of food and water by poisonous chemicals, often as a result of
overuse of fertilizers or waste spillages. People who consume food or water that has
been contaminated in this way can become seriously ill, either in the short or in the
longer term