Environmental pollution is the undesired spread of toxic chemicals into the aquatic and terrestrial habitats of the world. There are many different types of pollution, usually named for the location that has become polluted. For example, if oil is dumped into a local creek, it is said to be an example of water pollution.
Water, air and land pollution are three of the most common types of pollution. However, pollution often affects multiple systems. For example, if chemicals are burned in a factory, and the smoke rising out of the chimneys carries pollutants, the air becomes polluted. However, rain may cause some of this pollution to fall down to the land. Eventually, most of the pollution that strikes the ground will make its way to the water, where it will cause water pollution. Pollution can cause hardships for plants, animals and other organisms. Some organisms may eventually become endangered or extinct because of water, land or air pollution. Some environmentalists consider excess ambient light and sound to be forms of pollution as well. Light pollution can alter the behavior of wildlife and disrupt the circadian cycles of plants. Sound pollution in the ocean may be a cause of whale standings.