What is pollution?
Pollution means Contamination
Any substance added (naturally (e.g. volcanic eruption) or by human activities (industrial plants, motor vehicle traffic, etc.)) or accumulating in the atmosphere, hydrosphere, and lithosphere making them less desirable for people's use or retards healthy ecosystem functioning is pollution.
Especially after the industrial revolution (after 1850s), pollution became a serious issue due to machines consume fossil fuels (coal, gas, etc.). After 1960s, people started realization of heaşth effects of synthetic chemicals. Due to pollution, many people die or become sick nowadays. Cancer cases (such as air pollution and lung cancer) are also rising especially in developing countries.