Air pollution is anything that can become trapped in the atmosphere which can interfere with its normal function. Many gasses produced by society can become trapped in the atmosphere causing global warming, acid rain, and respiratory problems. Fine ash and other particulates can also become trapped until it is pushed out of the air by rain.
A few main causes of air pollution include but are not limited to industry, automobiles, and the production of energy. The smog that can sometimes be seen in larger cities is caused by pollution. The fuels used to power vehicles are a major contributing factor of air pollution.
Water pollution is caused by water runoff from farms and towns, industrial waste disposal, and anything man-made that ends up in the lakes, streams, and oceans. Much of the water pollution caused by farms is due to fertilizer and herbicides being washed out of the fields and into streams where it makes the long journey to the ocean.
Land pollution is also caused by industrial waste but can include pretty much anything that man has built, discarded, or just left lying around. People would generally not think of their house as a pollutant but in reality it could be considered pollution as it is not a natural occurrence and eventually it will either fall down or be torn down and end up in a landfill or trying to decompose where it falls.
Environmentalists have been trying to cut down on the amount of pollution that is produced by humankind for a number of years now but as the population of the planet increases the amount of pollution that is produced inevitably increases. We can try to slow down the increases but completely stopping pollution is not something that is going to happen.
There are a number of things that can be done to slow down the polluting of the environment and some of those things are cutting back on automobile traffic, recycling of waste products, and reusing as much of what we must remove from nature as possible.
Creating the least impact on the planet that we can is the next great challenge for the Human race. We may succeed or we may fail but to not try is not currently socially acceptable. The current fad of environmentalism seems to be staying around and all citizens of this great planet need to give lessening their impact on said planet a shot.